JP6097680B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, and a printer, a toner image formed on an image carrier by an image forming unit is transferred to a recording medium such as paper, and then the recording medium is a fixing device. It is conveyed to. In the fixing device, the toner image is fixed by heating the recording medium with a heating member such as a heater, and then the recording medium is discharged to a discharge tray. Therefore, since the recording medium immediately after being discharged is at a high temperature, when a large amount of recording medium is discharged, a large amount of heat is accumulated in the large number of recording media stacked on the discharge tray. . The heat accumulated on the recording medium may be transferred to the lower side of the paper discharge tray.

  In the image forming apparatus, a toner container such as a toner container is accommodated below the paper discharge tray. Then, the heat transmitted from the recording medium on the paper discharge tray to the lower side of the paper discharge tray is also transmitted to the toner container, and the toner in the toner container is heated to a high temperature. Thus, when the toner becomes high temperature, the toner particles are fused and solidified. As a result, it is difficult to obtain a good output image by the image forming operation using this toner. Toner clogging may occur, causing the device to malfunction.

  In order to avoid the problem caused by the heat of the recording medium on the paper discharge tray as described above, for example, there is a configuration in which external air is sent to the lower side of the paper discharge tray using a cooling fan. If the air can be sent and exhausted well to the lower side of the paper discharge tray, the heat of the recording medium loaded on the paper discharge tray will not be transferred to the toner container.

  For example, in Patent Document 1, a first air flow path for supplying air sucked from an intake fan (cooling fan) to a discharge tray (discharge tray) is located below the discharge tray. An image forming apparatus including a return air flow path for collecting air supplied from an air flow path to a discharge tray and a second air flow path for supplying air in the return air flow path into the image forming apparatus main body is disclosed. Has been. A toner cartridge (toner container) is disposed below the second air flow path.

  Further, Patent Document 2 discloses a paper discharge unit in which a plurality of ventilation holes are formed in a relay unit for transporting a sheet after image fixing from a vertical transporter to a post-processing device to release heat of the sheet after image fixing. A configuration with a tray is disclosed.

JP 2009-288742 A JP 2003-040508 A

  Incidentally, some image forming apparatuses are configured to perform an image forming operation using a plurality of types of recording media having different sizes. A recording medium having a long length in the paper discharge direction (for example, A3 size paper or B4 size paper) has a small number of prints per time and a recording medium having a short length in the paper discharge direction (for example, A4 size paper or B5 size paper). The number of sheets to be printed per time increases. Therefore, a recording medium with a short length in the paper discharge direction has a larger number of sheets per time on the paper discharge tray than a recording medium with a long length in the paper discharge direction, and the per unit area transmitted below the paper discharge tray. The amount of heat increases.

  However, in the configuration as described above, since the type of the recording medium discharged to the paper discharge tray is not taken into consideration, depending on the type of the recording medium, the amount of air sent below the paper discharge tray is insufficient, and a sufficient cooling effect is obtained. May not be obtained. Then, the heat of the recording medium loaded on the paper discharge tray is transmitted to the lower side of the paper discharge tray, and the toner stored in the toner container cannot be maintained well.

  For example, in Patent Document 1, regardless of the size of the recording medium, the air flowing from the first air flow path must pass through a long air path that passes through the return air flow path located far from the discharge roller. When a recording medium with a short length in the paper ejection direction is ejected, a large number of printing media per hour are discharged, so a large amount of recording medium is stacked near the ejection roller on the paper ejection tray, and a large amount of heat is accumulated. The However, the long air path described above has a large ventilation resistance, the air volume is reduced, and the space corresponding to the short recording medium under the paper discharge tray cannot be efficiently cooled. Therefore, the toner stored in the toner container below the paper discharge tray is heated, and the toner cannot be maintained in a good state. On the other hand, if the rotational speed of the cooling fan is increased in order to increase the air volume of the long air passage, there is a concern that power consumption increases or abnormal noise is generated.

  Further, in Patent Document 1, the air flowing from the first air flow path receives heat from the recording medium on the paper discharge tray and flows to the second air flow path via the return air flow path. The air heated by the heat passes through the second air flow path closer to the toner container. As a result, heat is transferred to the toner container, and the toner contained in the toner container may be heated.

  Further, in Patent Document 2, since a relay unit is premised, a problem that the heat of the recording medium on the discharge tray is transmitted to the lower side of the discharge tray is not considered. It is configured to escape to the lower side of the paper discharge tray through the vent hole. For this reason, the plurality of vent holes are also arranged at positions close to the discharge roller side. When a recording medium having a short length in the discharge direction is stacked on the discharge tray, the vent holes close to the discharge roller side are arranged. Will be blocked. At this time, radiant heat from the recording medium exposed when viewed from below the paper discharge tray enters the relay unit, and heat is accumulated below the paper discharge tray. Accordingly, when such a configuration is adopted for the paper discharge tray of the image forming apparatus, the toner contained in the toner container below the paper discharge tray is heated, and the toner cannot be maintained in a good state.

  In view of the above, the present invention takes into consideration the above situation and efficiently cools the space under the paper discharge tray regardless of the size of the recording medium, and the heat of the recording medium is accumulated under the paper discharge tray to create a toner. The purpose is to prevent it from reaching the container.

  An image forming apparatus according to the present invention includes a paper discharge tray on which a recording medium discharged from a paper discharge port after image forming processing is stacked, and a duct portion provided below the paper discharge tray. The tray is provided on the outer side along the outer periphery of the range in which the recording medium is stacked, and has a plurality of vent holes for communicating outside air and the duct portion.

  By adopting such a configuration, in the paper discharge tray, the opening and closing of the plurality of vents are switched according to the size of the stacked recording medium, and the duct flows in accordance with the size of the stacked recording medium. Air volume and ventilation resistance are adjusted. Accordingly, the space corresponding to the size of the recording medium loaded on the paper discharge tray is efficiently cooled in the space of the duct portion, so that the heat of the recording medium discharged on the paper discharge tray is discharged. Accumulation on the lower side of the paper tray can be prevented. As a result, the temperature rise of the toner container disposed below the paper discharge tray can be suppressed, and the toner contained in the toner container can be maintained in a good state.

  Among the plurality of vents, the vent closest to the paper discharge port is provided on the outer side along the outer periphery of the range in which the smallest size recording medium among the plurality of types of recording media having different sizes is stacked. It may be done.

  By adopting such a configuration, when the smallest recording medium with a large number of prints per hour and a large amount of heat transmitted under the discharge tray is stacked on the discharge tray, it corresponds to the smallest recording medium in the duct section. Since the distance of the air path from the air vent to be made is short and all the air vents are open and the opening area of the air vent to take air into the duct portion is maximized, the ventilation resistance of the duct portion is minimized. For this reason, the wind speed flowing through the space of the duct portion corresponding to the range of the minimum recording medium loaded on the paper discharge tray is increased, and a sufficient cooling effect is obtained.

  Among the plurality of vents, the vent farthest from the paper discharge port is provided on the outer side along the outer periphery of a range in which a maximum size recording medium is stacked among a plurality of types of recording media having different sizes. It may be done.

  By adopting such a configuration, the maximum recording medium discharged to the paper discharge tray will block the vent hole provided in accordance with the other recording medium, but it is provided in accordance with the maximum recording medium. Do not block the vents. Therefore, even when the largest recording medium is stacked on the paper discharge tray, the space of the duct portion corresponding to the range of the largest recording medium, that is, the entire area under the paper discharge tray can be cooled.

  The duct portion may include a shielding member between a bottom surface of the duct portion and the plurality of vent holes.

  By adopting such a configuration, the air vent corresponding to the predetermined recording medium is blocked by loading another recording medium longer in the paper discharge direction than the predetermined recording medium on the paper discharge tray. Even in this case, radiant heat from the recording medium loaded on the paper discharge tray is blocked by the shielding member. Therefore, even if the vent hole is opened in the paper discharge tray, heat is prevented from being directly transferred from the recording medium loaded on the paper discharge tray to the bottom surface of the duct portion. Heat transfer to the container is prevented. As a result, the toner stored in the toner container can be maintained in a good state.

  The plurality of vent holes may be formed so as to be inclined from the upper surface of the discharge tray toward the inside of the duct portion and the discharge port side.

  By adopting such a configuration, it becomes easy to take in the outside air on the surface side of the paper discharge tray through the vent. As a result, the wind speed flowing through the duct portion can be increased, and a sufficient cooling effect can be obtained. Further, when the recording medium loaded on the paper discharge tray closes the vent, the inclined inner wall surface can reduce the facing area between the recording medium and the bottom surface of the duct portion, and is transmitted from the recording medium into the duct portion. The amount of heat can also be reduced.

  According to the present invention, the space under the discharge tray is efficiently cooled regardless of the size of the recording medium, and the heat of the recording medium is prevented from being accumulated under the discharge tray and transmitted to the toner container. It becomes possible to do.

1 is a schematic diagram showing an outline of a configuration of a copying machine according to an embodiment of the present invention. FIG. 2 is a side sectional view showing the periphery of a paper discharge tray of a copying machine according to an embodiment of the present invention. FIG. 3 is an upper cross-sectional view showing the periphery of the paper discharge tray of the copying machine according to the embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a state in which sheets of a minimum size are stacked on a paper discharge tray of a copying machine according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a state in which sheets of the maximum size are stacked on a paper discharge tray of a copier according to an embodiment of the present invention. FIG. 5 is a cross-sectional view illustrating a state in which intermediate-size sheets are stacked on the paper discharge tray of the copying machine according to the embodiment of the present invention. FIG. 6 is a side sectional view showing the periphery of a paper discharge tray of a copying machine according to another embodiment of the present invention. FIG. 6 is a side sectional view showing the periphery of a paper discharge tray of a copying machine according to another embodiment of the present invention.

  Hereinafter, a copying machine 1 (image forming apparatus) according to an embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the front side of the drawing in FIGS. 1, 2, and 4 to 6 is the front side (front side) of the copying machine 1, and in FIG. 3, the front side of the copying machine 1 is indicated by an arrow Fr.

  First, the overall configuration of the copying machine 1 will be described with reference to FIG. The copying machine 1 includes a box-shaped copying machine main body 2. A paper feeding cassette 3 that stores paper (recording medium) is provided at the lower part of the copying machine main body 2. A tray 4 is provided. An image reading device 5 is provided above the discharge tray 4 at the upper end of the copying machine main body 2. In the copying machine main body 2, a toner container 18 such as a toner container is accommodated below the paper discharge tray 4. A duct portion 6 is provided between the paper discharge tray 4 and the toner container 18 along the lower side of the paper discharge tray 4, and a fan portion 7 is connected to the duct portion 6. Details of the paper discharge tray 4, the duct portion 6, and the fan portion 7 will be described later.

  In the central part of the copying machine main body 2, an intermediate transfer belt 8 is suspended by a plurality of rollers. Below the intermediate transfer belt 8, an exposure device 9 composed of a laser scanning unit (LSU) is disposed. Along the lower side of the intermediate transfer belt 8, four image forming units 10 are provided for each toner color (for example, four colors of magenta, cyan, yellow, and black). A cleaning device 11 is provided on the right side of the intermediate transfer belt 8.

  Each image forming unit 10 is rotatably provided with a photosensitive drum 12, and around the photosensitive drum 12, a charger 13, a developing unit 14, a primary transfer unit 15, a cleaning unit 16, and a removal unit. The electric devices 17 are arranged in the order of the primary transfer process. Above the developing unit 14, a toner container 18 corresponding to each image forming unit 10 is provided for each toner color (for example, four colors of magenta, cyan, yellow, and black).

  On one side of the copying machine main body 2 (left side in the drawing), a sheet conveyance path 20 is provided extending in the vertical direction. A paper feeding unit 21 is provided at the upstream end of the conveyance path 20, and a secondary transfer unit 22 is provided at one end (left end in the drawing) of the intermediate transfer belt 8 in the middle part of the conveyance path 20. A fixing device 23 is provided at the downstream portion of the transport path 20, and a paper discharge port 24 is provided at the downstream end of the transport path 20. The fixing device 23 is configured by, for example, a pressure roller 25 and a heating roller 26 arranged in pairs with the conveyance path 20 interposed therebetween. A pair of paper discharge rollers 27 are provided at the paper discharge port 24.

  Next, an image forming operation of the copying machine 1 having such a configuration will be described. When the copying machine 1 is turned on, various parameters are initialized, and initial setting such as temperature setting of the fixing device 23 is executed. When a document image is read by the image reading device 5, an image forming operation is executed as follows.

  First, in the image forming unit 10, the surface of the photosensitive drum 12 is charged by the charger 13, and then an electrostatic latent image is formed on the surface of the photosensitive drum 12 by the laser light (see arrow P) from the exposure device 9. Is done. Next, the electrostatic latent image is developed into a toner image of the corresponding color by the developing device 14 with the toner supplied from the toner container 18. This toner image is primarily transferred to the surface of the intermediate transfer belt 8 in the primary transfer portion 15. Each image forming unit 10 sequentially repeats the above operation, whereby a full-color toner image is formed on the intermediate transfer belt 8. Note that the toner and charges remaining on the photosensitive drum 12 are removed by the cleaning unit 16 and the static eliminator 17.

  On the other hand, the paper taken out from the paper feed cassette 3 or the hand tray (not shown) by the paper feed unit 21 is conveyed to the secondary transfer unit 22 in synchronism with the above-described image forming operation, and is subjected to secondary transfer. In the portion 22, the full color toner image on the intermediate transfer belt 8 is secondarily transferred to the paper. The sheet on which the toner image has been secondarily transferred is conveyed downstream in the conveyance path 20 and enters the fixing device 23 where the toner image is fixed on the sheet. The sheet on which the toner image is fixed is discharged from the discharge outlet 24 onto the discharge tray 4. In the following, for convenience of explanation, the discharge direction from the discharge port 24 is assumed to be the vertical direction.

  Next, the paper discharge tray 4 will be described with reference to FIGS.

  The paper discharge tray 4 is for stacking paper discharged from the paper discharge port 24 after image forming processing such as development processing, transfer processing, and fixing processing, and has an area on which a plurality of types of paper having different sizes can be stacked. Have. For example, when the copying machine 1 is a landscape A4 size paper (hereinafter referred to as a landscape A4 paper), a portrait B5 size paper (hereinafter referred to as a portrait B5 sheet), a portrait A4 size sheet (hereinafter referred to as a portrait A4 sheet). ), Portrait-oriented B4 size paper (hereinafter referred to as portrait B4 paper), and portrait-oriented A3 size paper (hereinafter referred to as portrait A3 paper). Of these plural types of sheets, the sheet has an area capable of stacking at least a vertical A3 sheet having the maximum size.

  The paper discharge tray 4 has a wall surface 30 standing below the paper discharge port 24 and an inclined surface 31 extending from the lower end of the wall surface 30 in the paper discharge direction. The paper discharged to the paper discharge tray 4 is stacked on the inclined surface 31, and one end in the paper discharge direction is aligned on the wall surface 30 side by the inclination of the inclined surface 31, and the other end is positioned for each paper size. It changes according to the length in different paper discharge directions. For example, the length L1, the length L2, the length L3, the length L4, and the length L5 in the paper discharge direction are respectively in the order of horizontal A4 paper, vertical B5 paper, vertical A4 paper, vertical B4 paper, and vertical A3 paper. It is getting longer.

  The inclined surface 31 of the paper discharge tray 4 is formed with a plurality of vent holes 32a, 32b, 32c, 32d, and 32e that allow the outside air to communicate with the duct portion 6 disposed below. The vents 32a, 32b, 32c, 32d, and 32e are formed in a rectangular shape having a length of 5 mm in the paper discharge direction and a length of 40 mm in the front-rear direction, for example.

  The plurality of vent holes 32a, 32b, 32c, 32d, and 32e are arranged at a predetermined interval from the wall surface 30 (that is, the discharge port 24 side), and the intervals are defined by the vent holes 32a, 32b, 32c, 32d, It becomes longer in the order of 32e. The plurality of vents 32a, 32b, 32c, 32d, and 32e are provided at positions corresponding to the plurality of types of paper that can be printed by the copying machine 1, and the vent 32a that is closest to the paper discharge port 24 is The vent 32e that is farthest from the paper stacking range with the shortest length in the paper ejection direction is spaced just outside the stacking range of the paper with the longest length in the paper ejection direction. It is done.

  For example, the vent hole 32a is located outward along the outer periphery of the range in which the horizontal A4 paper is stacked, and preferably, the horizontal A4 paper in a state where one end of the horizontal A4 paper is in contact with the wall surface 30 (that is, the discharge outlet 24 side) The other end position 33a is provided outside. The vent 32a is more preferably provided outside the other end position 33a by 0 to 2 mm. A plurality of, for example, four vent holes 32a are provided along the other end position 33a. Similarly, the vents 32b, 32c, 32c and 32e are respectively formed on the outside along the outer periphery of the stacking range of the vertical B5 paper, the vertical A4 paper, the vertical B4 paper and the vertical A3 paper. Is provided outside the other end positions 33b, 33c, 33d, and 33e of the respective sheets in a state where one end of the sheet is in contact with the wall surface 30 (that is, the discharge port 24 side). The vents 32b, 32c, 32c and 32e are more preferably provided outside the other end positions 33b, 33c, 33d and 33e by 0 to 2 mm. A plurality of, for example, four vent holes 32b, 32c, 32c and 32e are provided along the other end positions 33b, 33c, 33d and 33e, respectively.

  The duct portion 6 includes a tray lower duct 34 and a ventilation duct 35. The lower tray duct 34 extends over the entire area of the paper discharge tray 4 and communicates with the vent holes 32a, 32b, 32c, 32d, and 32e. The ventilation duct 35 communicates with the lower tray duct 34 on the left side of the lower tray duct 34, and the rear end extends to the back surface or the side surface of the copying machine main body 2.

  The fan unit 7 includes a cooling fan 36 and is attached to the rear end of the ventilation duct 35 of the duct unit 6. The cooling fan 36 takes in external air (outside air) into the duct 6 using the air vents 32a, 32b, 32c, 32d, 32e of the paper discharge tray 4 as air inlets and uses the fan unit 7 as an air outlet for cooling air intake. I am a fan.

  Next, the cooling operation of the discharge tray 4 will be described with reference to FIGS. 4 to 6 in addition to FIGS.

  As shown in FIGS. 2 and 3, on the lower side of the discharge tray 4, the lower tray tray 34 and the ventilation duct 35 of the duct portion 6 are provided from the vent holes 32 a, 32 b, 32 c, 32 d, and 32 e of the discharge tray 4. An air passage that leads to the fan unit 7 is provided. Then, when the cooling fan 36 of the fan unit 7 rotates, an air flow is generated in the above-described air path, so that the outside air passes through the vent holes 32a, 32b, 32c, 32d, and 32e of the paper discharge tray 4 and the duct unit. 6 is taken in. The air taken into the duct unit 6 flows in a direction parallel to and opposite to the paper discharge direction, passes through the tray lower duct 34 and the ventilation duct 35, and then passes through the fan unit 7 from the back surface of the copier body 2. It is discharged outside. In this way, the external air passes through the lower tray duct 34, whereby the paper discharge tray 4 above the lower tray duct 34 is cooled.

  A cooling operation when the smallest horizontal A4 sheet S1 in the sheet discharge direction among the plurality of types of sheets that can be printed by the copying machine 1 is discharged to the sheet discharge tray 4 will be described with reference to FIG. Such a minimum width A4 sheet S1 has a large number of printed sheets per time, and the amount of heat transmitted to the bottom of the sheet discharge tray 4 increases.

  In this case, the horizontal A4 paper S1 discharged to the paper discharge tray 4 has the shortest length L1 in the paper discharge direction. Therefore, not only the vent 32a provided for the horizontal A4 paper S1 but also the horizontal A4 paper S1. In addition, none of the vent holes 32b, 32c, 32d, and 32e provided for other sheets longer in the paper discharge direction is blocked. Therefore, when the cooling fan 36 of the fan unit 7 is driven, air is taken into the duct 34 below the tray of the duct unit 6 through all the vent holes 32a, 32b, 32c, 32d, and 32e from the front side of the paper discharge tray 4. . Then, cooling air is sent through a space located below the horizontal A4 sheet S1 on the discharge tray 4 in the space of the duct 34 below the tray.

  At this time, the distance from the air vent 32a corresponding to the lateral A4 sheet S1 to the air duct 35 in the duct portion 6 is short, and all the air vents 32a, 32b, 32c, 32d, 32e are open, and the lower duct 34 Since the opening area of the ventilation port for taking in air is the largest, the ventilation resistance of the duct 34 under the tray is the smallest. Therefore, even when the smallest horizontal A4 sheet S1 having a large number of prints per time and having a large amount of heat transmitted to the bottom of the discharge tray 4 is stacked on the discharge tray 4, it corresponds to the range of the stacked horizontal A4 sheets S1. The speed of the wind flowing through the space under the tray 34 is increased, and a sufficient cooling effect is obtained.

  A cooling operation when the largest vertical A3 sheet S2 in the sheet discharge direction among the plural types of sheets that can be printed by the copying machine 1 is discharged to the sheet discharge tray 4 will be described with reference to FIG. Such a maximum vertical A3 sheet S2 has a small number of printed sheets per time, and the amount of heat transmitted to the bottom of the sheet discharge tray 4 is smaller than other sheets that are short in the sheet discharge direction.

  In this case, the vertical A3 paper S2 discharged to the paper discharge tray 4 does not block the vent 32e provided in accordance with the vertical A3 paper S2, but the length L5 in the paper discharge direction is the longest. The vents 32a, 32b, 32c, and 32d provided for other sheets shorter in the paper discharge direction than the A3 sheet S2 are blocked. Therefore, when the cooling fan 36 of the fan unit 7 is driven, air is taken into the duct 34 below the tray 6 of the duct unit 6 from the front side of the paper discharge tray 4 through the vent 32e. Then, the cooling air is sent through the space located below the entire range of the vertical A3 sheet S2 on the discharge tray 4 in the space of the duct 34 below the tray.

  Therefore, even when the largest vertical A3 sheet S2 is stacked on the discharge tray 4, the space under the tray lower duct 34 corresponding to the range of the vertical A3 sheet S2, that is, the entire area below the discharge tray 4 is cooled. Can do.

  In addition, a cooling operation when a medium-sized sheet, for example, a vertical A4 sheet S3 among the plural types of sheets that can be printed by the copying machine 1 is discharged to the discharge tray 4 will be described with reference to FIG. The intermediate vertical A4 paper S3 has a smaller number of prints per hour than the smallest horizontal A4 paper S1, and therefore the amount of heat transferred below the paper discharge tray 4 is reduced, while compared to the maximum vertical A3 paper S2. Since the number of printed sheets per hour is large, the amount of heat transferred to the bottom of the paper discharge tray 4 increases.

  In this case, the vertical A4 paper S3 discharged to the paper discharge tray 4 is provided in accordance with the vent 32c provided in accordance with the vertical A4 paper S3 and other paper longer in the paper discharge direction than the vertical A4 paper S3. The vents 32d and 32e are not blocked, but the vents 32a and 32b provided for other sheets shorter in the paper discharge direction than the vertical A4 sheet S3 are blocked. Therefore, when the cooling fan 36 of the fan unit 7 is driven, air is taken into the duct lower tray 34 of the duct unit 6 from the surface side of the paper discharge tray 4 through the vent holes 32c, 32d, 32e. Then, the cooling air is sent through the space located below the vertical A4 sheet S3 on the discharge tray 4 in the space of the duct 34 below the tray.

  As described above, since air is taken in from the vent 32c arranged just outside the vertical A4 paper S3 loaded on the paper discharge tray 4, the increase in the airflow resistance of the duct 34 below the tray is caused by the vertical A4 paper S3. Depending on the length, it can be minimized.

  According to the present embodiment, as described above, the copying machine 1 is provided below the paper discharge tray 4 on which the paper discharged from the paper discharge port 24 after the image forming process is stacked. A plurality of ventilation holes 32a, 32b, 32c, and 32d that are provided outside along the outer periphery of the sheet stacking range and that communicate the outside air with the duct unit 6. , 32e.

  Thereby, in the paper discharge tray 4, the opening and closing of the plurality of vents 32a, 32b, 32c, 32d, and 32e are switched according to the size of the stacked paper, and the duct below the tray is adjusted according to the size of the stacked paper. The air volume and ventilation resistance of the air flowing through 34 are adjusted. Accordingly, the space corresponding to the size of the paper stacked on the paper discharge tray 4 in the space in the duct 34 below the tray is efficiently cooled, so that the heat of the paper discharged onto the paper discharge tray 4 can be reduced. Can be prevented from being accumulated on the lower side of the paper discharge tray 4 and transmitted to the toner container 18. As a result, the temperature rise of the toner container 18 disposed below the paper discharge tray 4 can be suppressed, and the toner stored in the toner container 18 can be maintained in a good state.

  Further, according to the present embodiment, among the plurality of vent holes 32a, 32b, 32c, 32d, and 32e, the vent hole 32a closest to the paper discharge port 24 is the smallest of the plural types of sheets having different sizes. It is provided on the outer side along the outer periphery of the range in which the size sheets are stacked.

  In this way, when the minimum number of sheets with a large number of prints per hour and a large amount of heat transmitted to the bottom of the discharge tray 4 are stacked on the discharge tray 4, the duct portion 6 has the vent 32 a corresponding to the minimum sheet. The distance to the air duct, for example, the distance to the air duct 35 is short, and all the air vents 32a, 32b, 32c, 32d, 32e are open, and the opening area of the air vent that takes air into the duct 34 below the tray Therefore, the draft resistance of the duct 34 under the tray is the smallest. Therefore, the wind speed flowing through the space in the lower duct 34 corresponding to the minimum sheet range loaded on the paper discharge tray 4 is increased, and a sufficient cooling effect is obtained.

  In addition, according to the present embodiment, among the plurality of vent holes 32a, 32b, 32c, 32d, and 32e, the vent hole 32e that is farthest from the paper discharge port 24 is the largest of a plurality of types of sheets having different sizes. It is provided on the outer side along the outer periphery of the range in which the size sheets are stacked.

  As a result, the maximum sheet discharged to the sheet discharge tray 4 blocks the vents 32a, 32b, 32c, and 32d provided for other sheets, but is provided for the maximum sheet. The vent 32e is not blocked. Therefore, even when the largest sheet is stacked on the discharge tray 4, the space in the lower duct 34 corresponding to the largest sheet range, that is, the entire area below the discharge tray 4 can be cooled.

  In the present embodiment, the configuration in which the vent holes 32a, 32b, 32c, 32d, and 32e are formed in a rectangular shape has been described. However, the present invention is not limited to this configuration. For example, in other embodiments, the vents 32a, 32b, 32c, 32d, 32e may be formed in a circular, elliptical, polygonal or other shape.

  Moreover, in other different embodiment, as FIG. 7 shows, the lower tray duct 34 of the duct part 6 may be comprised including the some shielding member 40a, 40b, 40c, 40d. The shielding members 40a, 40b, 40c, and 40d are the vent holes 32a, 32b, 32c, and 32d other than the vent hole 32e corresponding to the longest paper (for example, vertical A3 paper) in the paper discharge direction, and the bottom surface of the tray lower duct 34. Between each other. The shielding members 40a, 40b, 40c, and 40d are formed of an opaque material that does not transmit radiant heat from the paper. The shielding members 40a, 40b, 40c, and 40d are plate-like parallel to the inclined surface 31, and have a larger area than the vent holes 32a, 32b, 32c, and 32d, respectively.

  For example, the shielding member 40a may have a number equal to the number of the vent holes 32a along the other end position 33a, or may be formed of a single long plate along the other end position 33a. Also good. Similarly, the shielding members 40b, 40c, and 40d may have the same number as the vents 32b, 32c, and 32d along the other end positions 33b, 33c, and 33d, respectively, or the other end position 33b. , 33c, 33d may be formed of a single long plate.

  As a result, even if the vents 32a, 32b, 32c, and 32d are blocked by the loading of sheets that are longer than the corresponding sheets in the sheet discharge direction on the sheet discharge tray 4, they are stacked on the sheet discharge tray 4. The radiant heat from the sheet is blocked by the shielding members 40a, 40b, 40c, and 40d. For this reason, even if the vent holes 32a, 32b, 32c, and 32d are opened in the paper discharge tray 4, it is possible to prevent heat from being directly transferred from the paper stacked on the paper discharge tray 4 to the bottom surface of the tray lower duct 34. Therefore, heat is prevented from being transmitted to the toner container 18 below the duct 34 below the tray. As a result, the toner stored in the toner container 18 can be maintained in a good state.

  Further, in another different embodiment, as shown in FIG. 8, the vent holes 32a, 32b, 32c, 32d, 32e formed on the inclined surface 31 of the paper discharge tray 4 have inner wall surfaces 41a, 41b, 41c, 41d and 41e may be formed so as to be inclined to the inside of the lower tray duct 34 (duct portion 6) and to the wall surface 30 side (discharge port 24 side).

  Thereby, when the cooling fan 36 of the fan unit 7 rotates, the external air on the surface side of the paper discharge tray 4 is easily taken in through the vent holes 32a, 32b, 32c, 32d, and 32e. As a result, the wind speed flowing through the tray lower duct 34 can be increased, and a sufficient cooling effect can be obtained. In addition, when the sheets stacked on the discharge tray 4 block the vent holes 32a, 32b, 32c, and 32d, the inclined inner wall surfaces 41a, 41b, 41c, and 41d are opposed areas of the sheet and the bottom surface of the tray lower duct 34. , And the amount of heat transferred from the paper into the duct 34 under the tray can also be reduced.

  In this embodiment, the case where the configuration of the present invention is applied to the copying machine 1 has been described. However, in another different embodiment, the configuration of the present invention is applied to other image forming apparatuses such as a printer, a facsimile machine, and a multifunction peripheral. May be.

1 Copying machine (image forming device)
4 discharge tray 6 duct portion 7 fan portion 23 fixing device 24 discharge port 25 pressure roller 26 heating roller 27 discharge roller 30 wall surface 31 inclined surface 32a, 32b, 32c, 32d, 32e vent hole 34 duct under tray 35 ventilation Duct 36 Cooling fan 40a, 40b, 40c, 40d Shield member 41a, 41b, 41c, 41d, 41e Inner wall surface

Claims (5)

A paper discharge tray on which a recording medium discharged from the paper discharge port after the image forming process is stacked;
A duct portion provided below the paper discharge tray,
It said discharge tray is to have a plurality of vents which the recording medium is communicating with the outside air and the duct portion with provided outside along the outer circumference of the range to be stacked,
The image forming apparatus , wherein the duct portion includes a shielding member between a bottom surface of the duct portion and the plurality of vent holes .   Among the plurality of vents, the vent closest to the paper discharge port is outside along the outer periphery of the range in which the smallest size recording medium is stacked among the plurality of types of recording media having different sizes. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided.   Among the plurality of vents, the vent farthest from the discharge port is on the outer side along the outer periphery of the range in which the maximum size recording medium is stacked among the plurality of types of recording media having different sizes. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided.   The image according to any one of claims 1 to 3, wherein the plurality of vent holes are provided outside along the outer periphery of each range in which a plurality of types of recording media having different sizes are stacked. Forming equipment. Wherein the plurality of vents, the described from the upper surface of the discharge tray, to any one of claims 1 to 4, characterized in that it is formed to be inclined inwardly and the sheet discharge port side of said duct portion Image forming apparatus.

Images