JP2015229557A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device that cools efficiently a sheet bundle on a sheet discharge tray part 50 so as to prevent the sheet discharge tray 50 from being heated by residual heat of the sheet bundle without impairing stack performance of a sheet to be discharged onto the sheet discharge tray part 50.SOLUTION: On an upper surface of a sheet discharge tray part 50 are formed a plurality of rib parts 51 that are extended along a sheet discharging direction and arrayed at intervals from each other in a direction orthogonal to the sheet discharging direction; in a wall part 60a, in which a sheet discharge port 60f in an enclosure 60 is formed, are formed opening parts 60g communicating the adjacent rib parts 51; and in the enclosure 60 is provided a suction fan 72 that suctions outside air of the enclosure 60 through the opening parts 60g.

Description

  The present invention relates to an image forming apparatus including a fixing device.

  2. Description of the Related Art Conventionally, an image forming apparatus including a fixing device that heats and fixes a toner image transferred from a photosensitive drum onto a sheet is known. The fixing device is housed in the housing together with the photosensitive drum and the transfer roller. A transport path for transporting paper is set in the housing, and the fixing device is provided in the middle of the transport path. The paper that has passed through the fixing device is discharged and stacked, for example, on a paper discharge tray formed on the upper surface of the housing. The sheet bundle on the paper discharge tray portion is at a high temperature due to the influence of heat fixing in the fixing device. For this reason, the heat of the sheet is transmitted to the inside of the casing through the paper discharge tray portion, so that the optical components in the casing are thermally deformed and toner blocking (condensation of toner) occurs in the toner cartridge. There is.

  In order to solve these problems, for example, in the image forming apparatus disclosed in Patent Document 1, air is blown from above to the sheet bundle on the paper discharge tray section, thereby cooling the sheet bundle. This prevents the sheet discharge tray portion from being heated by the heat held by the sheet bundle.

JP 2012-155113 A

  However, in the image forming apparatus disclosed in Patent Document 1, since an air flow is blown from above on the sheet bundle on the paper discharge tray portion, each sheet moves due to wind pressure, and the stackability of the sheet bundle. There is a problem that is damaged.

  The present invention has been made in view of this point, and an object of the present invention is to stack a sheet bundle on the discharge tray unit without impairing the stackability of the sheets discharged onto the discharge tray unit. It is to cool efficiently.

  An image forming apparatus according to the present invention includes a housing that houses an image carrier therein, and a fixing device that is housed in the housing and that heat-fixes the toner image transferred from the image carrier to the paper on the paper. A paper discharge port formed in a wall portion of the housing for discharging the paper after passing through the fixing device to the outside of the housing; And a paper discharge tray portion on which paper discharged from the paper mouth is stacked.

  A plurality of rib portions extending along the paper discharge direction and arranged at intervals from each other in a direction perpendicular to the paper discharge direction are formed on the upper surface of the paper discharge tray portion, and the paper discharge in the housing is formed. An opening that communicates between the adjacent rib portions is formed in the wall portion in which the mouth is formed, and a suction fan that sucks air outside the housing from the opening in the housing Is provided.

  According to this configuration, when the suction fan is operated, air outside the housing flows between the adjacent rib portions and flows into the housing from the opening formed in the wall portion of the housing. The air flow passing between adjacent rib portions generates a negative pressure that draws the entire sheet bundle downward through the lower side of the sheet bundle. Therefore, the stackability of the sheet bundle can be improved. Further, since the entire sheet bundle can be cooled by this air flow, it is possible to prevent the discharge tray unit from being heated by the heat retained in the sheet bundle. In addition, this air flow is stratified between the sheet bundle and the paper discharge tray section, so that it is difficult for the hot air in the vicinity of the paper bundle and the cold air in the vicinity of the paper discharge tray section to be switched. . As a result, the temperature rise of the paper discharge tray is suppressed, and as a result, the optical components in the housing are thermally deformed by heat transfer from the paper discharge tray, and the toner in the toner cartridge is condensed (toner blocking). Can be prevented.

  Here, if the rear end of the paper bundle on the paper output tray (the downstream end in the paper output direction) is away from the wall of the housing, the rear end of the paper bundle will not pass through the lower side of the paper bundle. And an air flow toward the suction fan from between the wall of the housing and the housing. As a result, the flow rate of the air flow passing below the sheet bundle is reduced, and the negative pressure effect and the cooling effect due to the air flow may be impaired.

  In order to prevent this, the image forming apparatus further includes a plate-like portion that extends in a direction orthogonal to the paper discharge direction and covers the upstream ends of the plurality of rib portions in the paper discharge direction from above. .

  By doing so, the airflow from the rear end of the sheet bundle and the wall portion of the housing toward the suction fan can be blocked by the plate-like portion. Therefore, it is possible to ensure a sufficient flow rate of the air flow passing through the lower side of the sheet bundle. Therefore, it is possible to sufficiently ensure the negative pressure effect and the cooling effect due to the air flow.

  The paper discharge tray section is preferably inclined upward from the upstream side toward the downstream side in the paper discharge direction.

  According to this, the paper discharged to the paper discharge tray portion slides down from the downstream side in the paper discharge direction to the upstream side along the inclination of the paper discharge tray portion. Then, the slipped sheet stops when the rear end rides on the plate-like portion and comes into contact with the wall portion of the casing. In this way, the paper discharged from the paper discharge port can be accurately stacked at a predetermined position on the paper discharge tray.

  Here, consider a case where a sheet having a curl characteristic in which the central portion in the sheet width direction is convex upward is used. In this case, if the downstream edge in the paper discharge direction of the plate-like portion is orthogonal to the paper discharge direction, the paper stops when the trailing edge of the paper comes into contact with the downstream edge of the plate-like portion. There is a risk that.

  In order to prevent this problem, it is preferable to form notches at portions corresponding to both ends of the sheet in the width direction at the downstream edge of the plate-like portion in the paper discharge direction.

  According to this, when the paper slides down along the inclination of the paper discharge tray and the rear end of the paper collides with the downstream edge of the plate-like portion, both ends in the width direction of the paper A drag force is exerted on the portion from the inner edge of the notch to the outside in the direction orthogonal to the paper discharge direction. This drag acts to stretch the curled paper flat. Due to this action, the paper is lifted at the point of collision with the plate-like portion and rides on the upper side of the plate-like portion. Therefore, the rear end of all the sheets can ride on the upper side of the plate-like portion and abut against the wall portion of the housing. As a result, the stackability of the sheet bundle on the sheet discharge tray can be improved.

  In order to enhance the effect of extending the paper by the cutout portion, the inner edges of the two cutout portions are inclined toward the upstream side in the paper discharge direction toward the outside in the direction orthogonal to the paper discharge direction. Is preferred.

  The height of the opening is preferably smaller than the height of each rib.

  According to this configuration, when the wall portion of the housing is viewed from the paper discharge direction, the opening formed in the wall portion protrudes above the upper surface of the sheet bundle stacked on the upper side of each rib portion. Can be prevented. Thereby, the suction force of air by the suction fan can be sufficiently secured. Further, it is possible to prevent the rear end of each sheet constituting the sheet bundle from coming into contact with the peripheral edge of the opening and being damaged.

  The image forming apparatus further includes an air passage that extends along the wall portion in the casing and communicates between the adjacent rib portions through the opening, and the suction fan is disposed in the air passage. It is preferable that the air passage is provided between the paper discharge tray unit and the fixing device.

  According to this configuration, since the air passage is provided between the fixing device that is a heat source and the paper discharge tray unit, heat transfer from the fixing device to the sheet bundle on the paper discharge tray unit is performed by the air passage. Can be blocked. Therefore, the cooling effect of the sheet bundle is not hindered by the heat transfer from the fixing device.

  According to the present invention, it is possible to efficiently cool the sheet bundle on the paper discharge tray without impairing the stackability of the paper discharged on the paper discharge tray.

FIG. 1 is a schematic longitudinal sectional view showing an image forming apparatus according to an embodiment. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is a schematic plan view of the image forming apparatus as viewed from above. 4 is a cross-sectional view taken along line IV-IV in FIG. 5 is a cross-sectional view taken along line VV in FIG. FIG. 6 is an enlarged perspective view showing a notch formed in the plate-like portion. FIG. 7 is an explanatory diagram for explaining the curl removal effect of the paper by the notch formed in the plate-like portion.

Embodiment 1
FIG. 1 shows a laser printer 1 (hereinafter simply referred to as a printer) as an image forming apparatus in the present embodiment. The printer 1 has a housing 60 that houses the image forming unit 20 therein. A paper feed unit 10 is provided in the lower part of the housing 60, and a paper discharge tray unit 50 is formed on the upper surface of the housing 60. The image forming unit 20 and the fixing device 40 are disposed in the middle of the sheet conveyance path L from the sheet feeding unit 10 to the sheet discharge tray unit 50.

  The paper feeding unit 10 includes a paper feeding cassette 10a that stores sheet-like paper p in a bundled state, and a pickup roller 10b that takes out the paper p in the paper feeding cassette 10a and sends it out of the cassette 10a. doing. The paper p sent out of the cassette from the paper feed cassette 10 a is supplied to the image forming unit 20 through the transport roller pair 11.

  The image forming unit 20 includes a photosensitive drum (image carrier) 21, a charger 23, an exposure device 25, a developing device 27, a transfer device 29, and a fixing device 40. At the time of image formation, first, the peripheral surface of the photosensitive drum 21 is charged by the charger 23, and thereafter, original image data (for example, image data of the original image received from the external terminal) is applied to the surface of the photosensitive drum 21 by the exposure device 25. ) Is applied. Thus, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 21. The electrostatic latent image formed on the surface of the photosensitive drum 21 is developed as a toner image by the developing device 27. As a result, a toner image is formed (carried) on the surface of the photosensitive drum 21. The toner image is transferred to the paper p supplied from the paper supply unit 10 by the transfer device 29. The sheet p after the toner image is transferred is supplied to the fixing device 40 by the rotation of the transfer roller in the transfer unit 29. Reference numeral 33 in the figure denotes a cleaning device that removes residual toner on the surface of the photosensitive drum 21, and reference numeral 35 denotes a static eliminator.

  The fixing device 40 includes a fixing roller 40a with a built-in heater, and a pressure roller 40b that is pressed against the fixing roller 40a. In the fixing device 40, the paper p supplied from the transfer device 29 is heated and pressed between the fixing roller 40 a and the pressure roller 40 b to heat and fix the toner image on the paper p. The paper p on which the toner image is fixed by the fixing device 40 is sent out to the downstream side in the paper transport direction by both rollers 40a and 40b. The paper p sent out from the fixing device 40 is discharged from the paper discharge port 60 f of the housing 60 to the paper discharge tray unit 50 by the paper discharge roller pair 12.

  As shown in FIG. 2, the paper discharge port 60 f is formed in the vertical wall portion 60 a of the housing 60. The paper discharge tray unit 50 is inclined upward from the upstream side toward the downstream side in the paper discharge direction. The downstream side of the paper discharge tray 50 in the paper discharge direction is connected to the vertical wall 60a. As shown in FIG. 2, a plurality of openings 60g are formed at the lower end of the vertical wall 60a. The plurality of openings 60g have a long rectangular shape upward, and are formed at equal intervals in a direction orthogonal to the paper discharge direction.

  As shown in FIG. 3, a plurality of vertical plate-like rib portions 51 extending in the paper discharge direction are provided on the upper surface of the paper discharge tray portion 50. The plurality of rib portions 51 are arranged at equal intervals in a direction orthogonal to the paper discharge direction. The upstream end of each rib 51 in the paper discharge direction faces each opening 60g formed in the vertical wall 60a (see FIG. 2). The width W1 of the upstream end in the paper discharge direction of each rib 51 is smaller than the width W2 of the opening 60g. And each opening part 60g is connected between the rib parts 51 which adjoin each other. Further, the height H1 of the downstream end of each rib portion 51 in the paper discharge direction is larger than the height H2 of the opening 60g.

  A duct portion 71 having a U-shaped cross section is in contact with the inner surface of the vertical wall portion 60a (see FIGS. 4 and 5). The duct portion 71 and the vertical wall portion 60a form a hollow passage 75 having a rectangular cross section. The hollow passage 75 extends in a direction perpendicular to the paper discharge direction between the fixing device 40 and the paper discharge tray unit 50 (see FIG. 3). One end of the hollow passage 75 is closed by the side wall of the housing 60, and the other end of the hollow passage 75 is connected to an exhaust port 60 h formed on the side wall of the housing 60. A suction fan 72 is provided in the hollow passage 75 in the duct portion 71. In this embodiment, the suction fan 72 is provided in the vicinity of the exhaust port 60h. The suction fan 72 is controlled by the controller 100 (see FIG. 1). The controller 100 is configured to operate the suction fan 72 during execution of the image forming process in the image forming unit 20 and to stop the suction fan 72 while the image forming process is stopped.

  Referring to FIG. 3, the upstream end of each rib portion 51 in the paper discharge direction is covered from above by a plate-like portion 52. The plate-like portion 52 has a substantially rectangular plate shape and extends horizontally in a direction orthogonal to the paper discharge direction. A pair of notches 53 (see FIGS. 3 and 6) are formed at the downstream edge of the plate-like portion 52 in the paper discharge direction. The pair of notches 53 are formed at locations corresponding to both ends in the width direction of the paper p discharged to the paper discharge tray 50. The pair of notches 53 are substantially V-shaped in plan view. That is, the notch 53 has two edges 53a and 53b as shown in FIG. The inner edge portions 53a of the pair of notches 53 are inclined toward the upstream side in the paper discharge direction toward the outside in the direction orthogonal to the paper discharge direction. In the present embodiment, the outer edges 53b of the cutout portions 53 are inclined toward the downstream side in the paper discharge direction toward the outside in the direction orthogonal to the paper discharge direction. Note that the outer edge 53b does not necessarily have such an inclination, and may extend linearly along the paper discharge direction, for example.

  In the printer 1 configured as described above, when the image forming process in the image forming unit 20 is started, the suction fan 72 is driven by the controller 100. When the suction fan 72 is driven, the inside of the hollow passage 75 in the duct portion 71 becomes negative pressure. As a result, the air outside the housing 60 flows into the hollow passage 75 from the opening 60g of the vertical wall 60a through the space 54 between the adjacent ribs 51 (arrows in FIGS. 3 to 5). reference). The air flow passing between the adjacent rib portions 51 generates a negative pressure that draws the entire sheet bundle P downward through the lower side of the sheet bundle P. Therefore, the stackability of the sheet bundle P can be improved. Further, since the entire sheet bundle P can be cooled by this air flow, it is possible to prevent the discharge tray unit 50 from being heated by the heat retained by the sheet bundle P. Further, this air flow is stratified between the sheet bundle P and the paper discharge tray unit 50, so that the high-temperature air in the vicinity of the paper bundle P and the low-temperature air in the vicinity of the paper discharge tray unit 50 are switched. Make it difficult to wake up. Therefore, an increase in the temperature of the paper discharge tray unit 50 is suppressed. As a result, the optical components and the like in the housing 60 are thermally deformed by heat transfer from the paper discharge tray unit 50 and the toner in the toner cartridge is condensed (toner It is possible to prevent blocking.

  Here, if the rear end (downstream end in the paper discharge direction) of the sheet bundle P on the paper discharge tray section 50 is away from the vertical wall section 60a of the housing 60, it does not pass below the sheet bundle P. In addition, an air flow from the rear end of the sheet bundle P and the vertical wall portion 60a toward the suction fan 72 is generated. As a result, the flow rate of the air flow passing under the sheet bundle P is reduced, and the negative pressure effect and the cooling effect due to the air flow may be impaired.

  On the other hand, in the above-described embodiment, the upstream ends of the plurality of rib portions 51 in the paper discharge direction are covered with the plate-like portion 52 extending in the direction orthogonal to the paper discharge direction.

  By doing so, the airflow from the rear end of the sheet bundle P and the vertical wall portion 60 a of the housing 60 toward the suction fan 72 can be blocked by the plate-like portion 52. Therefore, it is possible to ensure a sufficient flow rate of the air flow passing through the lower side of the sheet bundle P. Therefore, the negative pressure effect and the cooling effect due to the air flow are not impaired.

  In the above embodiment, the paper discharge tray unit 50 is inclined upward from the upstream side in the paper discharge direction toward the downstream side.

  Accordingly, the paper p discharged to the paper discharge tray unit 50 slides down from the downstream side in the paper discharge direction to the upstream side along the inclination of the paper discharge tray unit 50. Then, when the rear end of the paper p rides on the plate-like portion 52 and comes into contact with the vertical wall portion 60a of the housing 60, the movement of the paper p stops. In this way, the paper p can be accurately stacked at a predetermined position on the paper discharge tray unit 50.

  Here, consider a case where a sheet p having a curl characteristic in which the central portion in the sheet width direction is convex upward is used. In this case, when the downstream edge of the sheet-like portion 52 in the paper discharge direction is orthogonal to the paper discharge direction, the rear end of the paper p is in contact with the downstream edge of the plate-like portion 52. There is a possibility that the paper p stops.

  On the other hand, in the above-described embodiment, the portions corresponding to both ends in the width direction of the paper p (the paper p having the curl characteristics) at the downstream edge in the paper discharge direction in the plate-like portion 52 are substantially V. A letter-shaped cutout 53 is formed, and the inner edges 53a of the two cutouts 53 are inclined toward the upstream side in the paper discharge direction toward the outside in the direction orthogonal to the paper discharge direction.

  According to this configuration, when the paper p slides down along the inclination of the paper discharge tray portion 50 and the rear end of the paper p collides with the downstream edge of the plate-like portion 52, the paper p A drag force Fout (see FIG. 7) is applied to both ends in the width direction from the inner edge 53a of the notch 53 toward the outside in the direction orthogonal to the paper discharge direction. The drag Fout acts to stretch the curled paper p in a flat shape. By this action, the paper p is lifted at the position of collision with the plate-like portion 52 and rides on the upper side of the plate-like portion 52. Therefore, the rear ends of all the sheets p can be ridden on the upper side of the plate-like portion 52 and brought into contact with the vertical wall portion 60 a of the housing 60. As a result, the stackability of the sheet bundle P on the paper discharge tray section 50 can be improved.

  Moreover, in the said embodiment, the height H2 of each opening part 60g formed in the vertical wall part 60a is smaller than the height H1 of each rib part 51. FIG.

  Therefore, when the vertical wall portion 60a of the housing 60 is viewed from the paper discharge direction, the upper end portion of each opening portion 60g is prevented from protruding above the upper surface of the sheet bundle P stacked on the upper side of the rib portion 51. can do. Thereby, the air suction force by the suction fan 72 can be sufficiently secured. Further, it is possible to prevent the rear end of each sheet p constituting the sheet bundle P from coming into contact with the peripheral edge of each opening 60g and being damaged.

  In the above-described embodiment, the housing 60 is provided with the hollow passage 75 that extends along the vertical wall portion 60a and communicates between the adjacent rib portions 51 through the plurality of openings 60g. The hollow passage 75 is disposed between the fixing device 40 serving as a heat source and the paper discharge tray unit 50, so that heat transfer from the fixing device 40 to the sheet bundle P on the paper discharge tray unit 50 is performed. Can be blocked by the hollow passage 75. Therefore, the cooling effect of the sheet bundle P is not hindered by the heat transfer from the fixing device 40.

<< Other embodiments >>
In the above embodiment, an example in which the image forming apparatus 1 is the laser printer 1 has been described. However, the present invention is not limited to this, and the printer 1 may be, for example, a copying machine or a multifunction machine.

  In the above embodiment, a plurality of openings 60g are formed in the vertical wall 60a. However, the present invention is not limited to this, and the number of openings 60g may be one, for example.

  Moreover, in the said embodiment, although the notch part 53 is formed in substantially V shape, you may make it form not only in this but a parallelogram shape or trapezoid shape, for example.

  As described above, the present invention is useful for an image forming apparatus including a fixing device.

p Paper 1 Laser printer (image forming device)
21 Photosensitive drum (image carrier)
40 Fixing device 50 Paper discharge tray portion 51 Rib portion 52 Plate-like portion 53 Notch portion 53a Inner edge 60 Case 60a Vertical wall portion (wall portion)
60 f Paper discharge port 60 g Opening 72 Suction fan 75 Hollow passage (air passage)

Claims (5)

A housing that houses an image carrier therein, a fixing device that is housed in the housing and that heats and fixes the toner image transferred from the image carrier to the paper, and the paper that has passed through the fixing device Is discharged to the outside of the casing, and is connected to a surface of the wall on the outer side of the casing, and the sheet discharged from the outlet is stacked. An image forming apparatus including a paper discharge tray unit,
On the upper surface of the paper discharge tray portion, a plurality of rib portions are formed that extend along the paper discharge direction and are arranged at intervals in a direction orthogonal to the paper discharge direction.
An opening that communicates between the adjacent rib portions is formed in the wall portion of the housing where the paper discharge port is formed.
A suction fan that sucks air outside the housing from the opening is provided in the housing.
An image forming apparatus, further comprising: a plate-like portion that extends in a direction orthogonal to the paper discharge direction and covers the upstream ends of the plurality of rib portions in the paper discharge direction from above. The image forming apparatus according to claim 1.
The paper discharge tray section is inclined upward from the upstream side to the downstream side in the paper discharge direction,
An image forming apparatus in which notches are respectively formed in portions corresponding to both end portions in the width direction of the sheet at the downstream edge portion in the sheet discharge direction in the plate-like portion. The image forming apparatus according to claim 2.
The image forming apparatus, wherein inner edges of the two notches are inclined toward the upstream side in the paper discharge direction toward the outside in the direction orthogonal to the paper discharge direction. The image forming apparatus according to any one of claims 1 to 3,
The height of the said opening part is an image forming apparatus smaller than the height of each said rib part. The image forming apparatus according to any one of claims 1 to 4,
A hollow passage that extends along the wall portion in the housing and communicates between the adjacent rib portions through the opening,
The suction fan is provided in the hollow passage;
The hollow passage is an image forming apparatus provided between the paper discharge tray section and the fixing device.

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