JP6115348B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a duct that guides air from a blower to a plurality of image forming units.

  Conventionally, as an image forming apparatus, in order to send air substantially uniformly from a duct to a plurality of image forming units, a rib protruding toward the inside of the duct is provided at the downstream end of a plurality of exhaust ports formed in the duct. The thing is known (refer patent document 1). Specifically, in this technique, the protrusion amount of the rib is gradually increased from the upstream side toward the downstream side, thereby reducing the difference in the amount of air discharged from each exhaust port toward each image forming unit. doing.

JP 2010-237451 A

  By the way, when a shielding part that blocks a part of the flow path is arranged in the duct, even if the relationship between the upstream end and the downstream end of each exhaust port is configured as in the prior art, due to the influence of the shielding part, There is a problem that the difference in the amount of air discharged from each exhaust port cannot be reduced.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of reducing a difference in the amount of air discharged from each exhaust port even when a shielding portion is disposed in a duct. .

In order to solve the above problems, an image forming apparatus according to the present invention includes a plurality of image forming units that have a photosensitive drum rotatable around a rotation axis and are arranged in an arrangement direction orthogonal to the rotation axis. A blower that blows air; and a duct that guides air from the blower to the plurality of image forming units.
The duct extends in the arrangement direction and blocks a main body portion provided with a plurality of exhaust ports for discharging air toward each of the plurality of image forming units, and a part of a flow path in the main body portion. And a shielding portion provided as described above.
The plurality of exhaust ports are a first exhaust port disposed on the upstream side in the air blowing direction with respect to the shielding portion, a downstream side in the air blowing direction with respect to the first exhaust port, and an upstream side in the air blowing direction with respect to the shielding portion. At least a second exhaust port.
The amount of protrusion toward the inside of the main body at the downstream end with respect to the upstream end of the first exhaust port is larger than the amount of protrusion toward the inside of the main body at the downstream end with respect to the upstream end of the second exhaust port.

  According to this configuration, by providing a shielding part that shields a part of the flow path in the main body part, air easily flows into the second exhaust port on the side near the shielding part due to a pressure increase near the upstream end of the shielding part. Even in this case, by making the protruding amount at the downstream end of the first exhaust port larger than the protruding amount at the downstream end of the second exhaust port, air can easily flow into the first exhaust port. Therefore, the difference in the amount of air discharged from each exhaust port can be reduced.

  Further, in the above-described configuration, the plurality of exhaust ports have a third exhaust port disposed on the downstream side in the air blowing direction with respect to the shielding portion, and the main body portion at the downstream end with respect to the upstream end of the third exhaust port The amount of protrusion toward the inside of the first exhaust port may be larger than the amount of protrusion toward the inside of the main body at the downstream end with respect to the upstream end of the first exhaust port.

  According to this, although it becomes difficult for air to flow to the downstream side of the shielding part due to the pressure increase in the vicinity of the shielding part, by increasing the protruding amount of the downstream end of the third exhaust port downstream of the shielding part, This makes it easier for air to flow into the third exhaust port. As a result, the difference in the amount of air discharged from each exhaust port can be reduced.

  Further, in the above-described configuration, the plurality of exhaust ports include a fourth exhaust port disposed on the downstream side in the air blowing direction with respect to the third exhaust port, and the main body portion is provided with the plurality of exhaust ports. A first wall and a second wall facing the first wall, wherein the shielding portion is between the first wall and the second wall, the first wall and the second wall. It may be arranged away from.

  According to this, the air passing between the second wall and the shielding portion flows smoothly toward the fourth exhaust port without being disturbed by the projecting downstream end of the third exhaust port provided in the first wall. Therefore, air easily flows into the fourth exhaust port. As a result, the difference in the amount of air discharged from each exhaust port can be reduced.

  Further, in the above-described configuration, the shielding portion may have an upstream inclined wall that is inclined so as to be gradually separated from the inner surface of the main body portion toward the upstream side in the air blowing direction.

  According to this, since it can suppress that the cross-sectional area of a flow path becomes small rapidly in the vicinity of a shielding part, air can flow smoothly in a main-body part.

  Further, in the above-described configuration, a downstream inclined wall is provided on the downstream side of the upstream inclined wall in the blowing direction so as to be gradually separated from the inner surface of the main body portion toward the downstream side in the blowing direction. May be.

  According to this, since it can suppress that the cross-sectional area of a flow path becomes large suddenly in the downstream of an upstream inclined wall, air can be smoothly flowed in a main-body part.

  Further, in the above-described configuration, a frame that supports the plurality of image forming units and in which the duct is provided, and a beam-shaped member that is configured in a long shape and is fixed to the frame while penetrating the duct. The beam-shaped member may be disposed so as to pass between the upstream inclined wall and the downstream inclined wall.

  According to this, by arranging the beam-like member so as to pass between the upstream-side inclined wall and the downstream-side inclined wall, the upstream-side inclined wall and the downstream-side inclined wall prevent the air flow from being disturbed by the beam-like member. Therefore, air can flow smoothly in the main body.

  Moreover, in the above-described configuration, the first wall provided with at least the plurality of exhaust ports among the walls configuring the duct may be formed integrally with the frame.

  According to this, a part of the wall of the duct is formed integrally with the frame. Can be reduced. Further, for example, compared to a mode in which the wall having the exhaust port is separated from the frame, no gap is formed between the wall having the exhaust port and the frame, so that the air blowing efficiency can be improved.

  According to the present invention, even when a shielding part that blocks a part of the flow path is arranged in the duct, the difference in the amount of air discharged from each exhaust port can be reduced.

1 is a cross-sectional view illustrating a color printer according to an embodiment of the present invention. It is sectional drawing which shows the state which pulled out the drawer from the apparatus main body. It is a perspective view which shows the structure of an apparatus main body. It is a disassembled perspective view which shows a duct and each beam-shaped sheet metal. It is the side view which looked at the right side frame from the left-right direction outer side. It is sectional drawing (a) which shows the state which removed the shielding member and the 2nd duct part from the 1st duct part, and sectional drawing (b) which shows the state which attached the shielding member and the 2nd duct part to the 1st duct part. . It is a perspective view which shows a shielding member. It is the side view which looked at the right side frame from the left-right direction inner side.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, the overall configuration of a color printer as an example of an image forming apparatus will be described, and then the features of the present invention will be described in detail.

  In the following description, the direction will be described with reference to the user when using the color printer. That is, in FIG. 1, the left side toward the paper surface is “front side”, the right side toward the paper surface is “rear side”, the rear side toward the paper surface is “left side”, and the front side toward the paper surface is “right side”. To do. In addition, the vertical direction toward the page is defined as the “vertical direction”.

  As shown in FIG. 1, the color printer 1 includes an image forming unit in which a paper feeding unit 20 that supplies paper P, an image forming unit 30 that forms an image on the fed paper P, and an image are formed. And a paper discharge section 90 for discharging the paper P. The structure of the apparatus main body 10 will be described in detail later.

  The paper feed unit 20 mainly includes a paper feed tray 21 that stores the paper P and a paper transport device 22 that transports the paper P from the paper feed tray 21 to the image forming unit 30.

  The image forming unit 30 mainly includes an optical scanner 40, four process units 50 as an example of a plurality of image forming units, a drawer 60, a transfer unit 70, and a fixing unit 80.

  The optical scanner 40 is disposed above the plurality of process units 50, and includes a laser light emitting unit (not shown), a polygon mirror, a lens, a reflecting mirror, and the like that are not shown. In the optical scanner 40, the laser beam is reflected by a polygon mirror or a reflecting mirror or passes through a lens and is emitted and irradiated onto the surface of each photosensitive drum 51 of each process unit 50 by high-speed scanning. The

  The plurality of process units 50 are arranged in the arrangement direction orthogonal to the rotation axis of the photosensitive drum 51, that is, the front-rear direction in the present embodiment. The process unit 50 includes a photosensitive drum 51 that can rotate around a rotation axis in the left-right direction, a charger 52 for charging the photosensitive drum 51, and a developing cartridge 53. The developing cartridge 53 includes a developing roller 54 and a supply roller 55 for supplying toner to the photosensitive drum 51, and a toner storage chamber 56 for storing toner.

  The charger 52 includes a charging wire 52A and a grid electrode 52B provided between the charging wire 52A and the photosensitive drum 51.

  The drawer 60 is a member for supporting the plurality of process units 50, and is configured to be movable in the front-rear direction with respect to the pair of side frames 12 and 13 constituting the left and right walls of the apparatus main body 10. Specifically, each side frame 12, 13 is provided with a rail RA extending in the front-rear direction (shown only on the left side in FIGS. 2 and 3), and the drawer 60 is guided by each rail RA and is movable in the front-rear direction. . As shown in FIG. 2, the drawer 60 is configured to be able to be pulled out of the apparatus body 10 through an opening 10A formed by opening the front cover 11 disposed on the front surface of the apparatus body 10. As a result, the process unit 50 can be exposed to the outside.

  Returning to FIG. 1, the transfer unit 70 is provided between the paper feeding unit 20 and the drawer 60, and includes a driving roller 71, a driven roller 72, a conveyance belt 73, and a transfer roller 74.

  The driving roller 71 and the driven roller 72 are arranged in parallel in a spaced manner in the front-rear direction, and a conveyance belt 73 formed of an endless belt is stretched between them. The outer surface of the conveyance belt 73 is in contact with each photosensitive drum 51. In addition, four transfer rollers 74 that sandwich the conveyor belt 73 with the respective photosensitive drums 51 are arranged inside the conveyor belt 73 so as to face the respective photosensitive drums 51. A transfer bias is applied to the transfer roller 74 by constant current control during transfer.

  The fixing unit 80 is disposed on the rear side of the drawer 60 and the transfer unit 70, and includes a heating roller 81 and a pressure roller 82 that is disposed to face the heating roller 81 and presses the heating roller 81.

  In the image forming unit 30 configured as described above, first, the surface of each photosensitive drum 51 is uniformly charged by the charger 52 and then exposed by the optical scanner 40. As a result, the exposed portion of the electric charge is removed, and an electrostatic latent image based on the image data is formed on each photosensitive drum 51. Thereafter, the toner in the developing cartridge 53 is supplied to the electrostatic latent image on the photosensitive drum 51 by the developing roller 54, so that the toner image is carried on the photosensitive drum 51.

  Next, the paper P supplied on the conveyor belt 73 passes between each photosensitive drum 51 and each transfer roller 74, so that the toner image formed on each photosensitive drum 51 is placed on the paper P. Transcribed. Then, as the paper P passes between the heating roller 81 and the pressure roller 82, the toner image transferred onto the paper P is thermally fixed.

  The paper discharge unit 90 mainly includes a plurality of transport rollers 91 that transport the paper P. The sheet P on which the toner image has been transferred and heat-fixed is transported by the transport roller 91 and discharged outside the apparatus main body 10.

<Configuration of Device Main Body 10>
As shown in FIG. 3, the apparatus main body 10 includes a pair of left and right side frames 12 and 13, a first connection frame 100 that connects the upper portions of the side frames 12 and 13, and a lower rear portion of the side frames 12 and 13. And a lower beam 14 for connecting the lower end portions of the side frames 12 and 13 to each other. The first connection frame 100 and the second connection frame 200 are metal frames, and are configured in a cylindrical shape in which a cross section orthogonal to the left-right direction is a closed cross-sectional shape, and both ends in the left-right direction are a pair of side frames 12, 13. The cylindrical first connection frame 100 houses the optical scanner 40 (see FIG. 1), and the cylindrical second connection frame 200 has a power supply substrate for supplying power to the process unit 50. 400 (see FIG. 1) is accommodated. The lower beam 14 is a long sheet metal that is long in the left-right direction, and is provided on the front side and the rear side of each side frame 12, 13.

  Each of the side frames 12 and 13 is a rectangular substantially plate-shaped resin frame. As shown in FIG. 1, the side frames 12 and 13 are opposed to each other with a plurality of process units 50 interposed therebetween in the left-right direction. It is comprised so that it may support. In the following description, the side frame 12 disposed on the right side is also referred to as the right side frame 12, and the side frame 13 disposed on the left side is also referred to as the left side frame 13.

  The right side frame 12 is an example of a frame, and supports the right end side of each process unit 50 via a drawer 60. As shown in FIG. 3, the right side frame 12 includes a plate-like portion 121 having a plane 121A orthogonal to the left-right direction, and a reinforcing rib portion 122 formed so as to protrude from the plate-like portion 121 to the inside or outside in the left-right direction. And has mainly. Further, the right side frame 12 is provided with a first beam-shaped sheet metal 510, a second beam-shaped sheet metal 520, and a duct 600, which will be described in detail later.

  The left side frame 13 faces the right side frame 12 with the process unit 50 interposed therebetween, and supports the left end side of each process unit 50 via a drawer 60. The left side frame 13 also includes a plate-like portion and a reinforcing rib portion (reference numeral omitted) similar to the right side frame 12. In addition, a drive mechanism (not shown) including a plurality of gears for driving the photosensitive drum 51 and the like is provided on the outer side of the left side frame 13 in the left-right direction. 13 is reinforced.

  As shown in FIG. 2, the L-shaped sheet metal 300 includes a main body portion 300A extending in the front-rear direction and an extending portion 300B extending downward from the main body portion 300A, that is, toward the photosensitive drum 51. The main body 300 </ b> A is disposed so as to overlap the first connection frame 100 when projected in the left-right direction of the photosensitive drum 51. The extension part 300 </ b> B supports a positioning shaft 310 (see also FIG. 1) that engages with the rear part of the drawer 60 in order to position the drawer 60. The L-shaped metal plate 300 is fixed to the inner sides of the side frames 12 and 13 in the left-right direction.

  As shown in FIG. 4, the first beam-like metal plate 510 made of metal such as iron is an example of a beam-like member, is formed in a long shape extending in the vertical direction, and is formed of the plate-like portion 121 of the right side frame 12. It arrange | positions along the plane 121A and is being fixed to the said right side frame 12 from the left-right direction outer side. As a result, since the resin-made right side frame 12 is reinforced by the first beam-like sheet metal 510, it is possible to increase the rigidity of the right side frame 12 as compared with, for example, a structure in which the right side frame is made of only resin. It has become.

  The maximum width in the short direction of the first beam-shaped sheet metal 510 is formed to be an extremely small width of about 1/47 of the maximum length in the front-rear direction of the right side frame 12. By providing the first beam-like sheet metal 510 that is extremely narrow with respect to the resin-made right side frame 12, the color printer 1 is lighter than a conventional structure in which the side frame is formed of a large sheet metal. Can be achieved. The maximum width in the short direction of the first beam-like sheet metal 510 is desirably 1/10 to 1/100 of the maximum length in the front-rear direction of the right side frame 12, and preferably 1/40 to 1 / 50 is desirable.

  The first beam-like sheet metal 510 is arranged so as to vertically penetrate a duct 600 provided in the right side frame 12, and an upper end portion thereof is fixed to the upper portion of the right side frame 12 with a screw S1, and a lower end portion thereof is arranged on the right side. The lower portion of the side frame 12 is engaged. The first beam-shaped sheet metal 510 is formed by bending a long sheet metal into an L shape in cross-sectional view, and mainly includes a first wall 511 orthogonal to the left-right direction, and the first wall 511. And a second wall 512 extending outward in the left-right direction from the front end.

  The second beam-shaped sheet metal 520 has the same structure as that of the first beam-shaped sheet metal 510, and more specifically, the first wall 521 and the second wall having the same structure as the first wall 511 and the second wall 512 of the first beam-shaped sheet metal 510. A wall 522 is included. The second beam-shaped sheet metal 520 is disposed on the inner side in the left-right direction than the first beam-shaped sheet metal 510, and is fixed to the right side frame 12 along the front-rear direction so as to be orthogonal to the first beam-shaped sheet metal 510. ing. Specifically, the second beam-shaped sheet metal 520 and the first beam-shaped sheet metal 510 are arranged so as to cross in a cross shape so that the central portions overlap each other when viewed from the left-right direction.

  The second beam-like metal plate 520 has a first wall 521 arranged along a plane 121A (see FIG. 3) of the plate-like portion 121 of the right side frame 12, and the tip of the second wall 522 is directed inward in the left-right direction. Is placed in the state where That is, it arrange | positions so that the front-end | tip of each 2nd wall 512,522 of each beam-like sheet metal 510,520 may face the mutually opposite direction. The second beam-shaped sheet metal 520 has a front end fixed to the right side frame 12 and a rear end engaged with the right side frame 12.

  The duct 600 is an air flow path for guiding the air from the blower 700 that blows air into the chargers 52 of the plurality of process units 50, and is a U-shaped cross-sectional view formed integrally with the right side frame 12. 1st duct part 610, the 2nd duct part 620 provided so that opening of the 1st duct part 610 of cross-sectional U-shape may be covered, and the shielding member 630 provided in the duct 600 are comprised. ing.

  As shown in FIGS. 4 and 5, the first duct portion 610 includes a first main body portion 610A extending in the front-rear direction and a first extending portion 610B extending downward from the front end of the first main body portion 610A. Yes. On the other hand, the 2nd duct part 620 is formed with the film-like member, and has 2nd main-body part 620A extended in the front-back direction, and 2nd extension part 620B.

  And if the film-like 2nd duct part 620 is attached to the opening end of the 1st duct part 610 of cross-sectional U-shape, the bottomed cylinder extended in the front-back direction with the 1st main body part 610A and the 2nd main body part 620A A main body portion 600A is formed, and the first extension portion 610B and the second extension portion 620B constitute a cylindrical extension portion 600B for guiding air from the blower 700 to the main body portion 600A. It has become.

  The first main body portion 610A includes a bottom wall portion 611 as an example of a first wall, a pair of side wall portions 612 extending from the upper and lower ends of the bottom wall portion 611 in the left-right direction, the bottom wall portion 611 and the pair of side wall portions. And a rear wall portion 613 provided at the rear end of 612. The bottom wall portion 611 is a wall that extends in the front-rear direction and has a surface orthogonal to the left-right direction, and discharges air toward each of the plurality of chargers 52 at a position corresponding to each process unit 50. The first exhaust port 641, the second exhaust port 642, the third exhaust port 643, and the fourth exhaust port 644 are formed to be aligned in the front-rear direction. The first exhaust port 641, the second exhaust port 642, the third exhaust port 643, and the fourth exhaust port 644 are arranged in this order from the upstream side in the air blowing direction (see the arrow in FIG. 5). The structure around each of the exhaust ports 641 to 644 will be described in detail later.

  The pair of side wall portions 612 are walls that extend in the front-rear direction and have surfaces that are perpendicular to the up-down direction, and also function as reinforcing rib portions that reinforce the right side frame 12. The rear wall portion 613 is a wall having a surface orthogonal to the front-rear direction, and also functions as a reinforcing rib portion that reinforces the right side frame 12. The distance between the pair of side wall portions 612 is substantially equal in the first main body portion 610A.

  As shown in FIG. 6 (a), the first beam-shaped sheet metal 510 is passed through the pair of side wall portions 612 at substantially the center in the front-rear direction (between the second exhaust port 642 and the third exhaust port 643). A groove 612A is formed. The groove 612A is formed with a width substantially the same as the width (length in the short direction) of the first wall 511 of the first beam-shaped sheet metal 510, and the height (short-length) of the second wall 512 of the first beam-shaped sheet metal 510. It is formed with a depth greater than the length in the direction). Further, the bottom of the groove 612A is disposed at a position away from the bottom wall portion 611 in the left-right direction. Thus, in a state where the first beam-like sheet metal 510 is set in the groove 612A, the first beam-like sheet metal 510 is separated from the bottom wall portion 611 of the duct 600 and the second duct portion 620 (see FIG. 6B). It is arranged.

  As shown in FIGS. 6B and 7, the shielding member 630 is a resin member, and a part thereof (upstream inclined wall 632 and downstream inclined wall 633 described later) is a main body portion 600 </ b> A of the duct 600. It is provided so as to block a part of the inner flow path. That is, the cross-sectional area of the flow path of the main body 600A is small at the portion where the shielding member 630 is provided. Specifically, the shielding member 630 is disposed between the second exhaust port 642 and the third exhaust port 643 in the front-rear direction, and mainly includes a pair of side walls 631 and an upstream inclined wall 632 as an example of a shielding unit, and A downstream inclined wall 633 is integrally provided.

  Each side wall 631 is a wall for closing the groove 612A shown in FIG. 6A, and is disposed so as to contact the inner surfaces of the pair of side wall portions 612 of the first duct portion 610. An L-shaped groove 631A having a shape corresponding to the L-shaped first beam-shaped sheet metal 510 is formed.

  Engagement pieces 631B and 631C projecting outward in the vertical direction are formed at the right end of each side wall 631. The lower engagement piece 631B is formed to be smaller in the front-rear direction than the upper engagement piece 631C, and the center thereof is displaced in the front-rear direction with respect to the center of the upper engagement piece 631B. On the other hand, at the ends on the outer side in the left-right direction of the pair of side wall portions 612 of the first duct portion 610, notches 612B having shapes corresponding to the engagement pieces 631B and 631C (the upper notches in FIG. 6A). Only the portion 612B is shown).

  Thus, by providing the engagement pieces 631B and 631C having different shapes and arrangements and the cutout portions 612B having shapes corresponding to the engagement pieces 631B and 631C, the operator mistakes the direction of the shielding member 630 in the front-rear direction. Can be easily suppressed.

  The upstream inclined wall 632 is provided between the pair of side walls 631 and is inclined with respect to the blowing direction as shown in FIG. Specifically, the upstream inclined wall 632 is inclined so as to be gradually separated from the inner surface of the main body portion 600A (the inner surface of the second duct portion 620) toward the upstream side in the air blowing direction (the direction of the arrow in the figure). Yes. Thereby, since it can suppress that the cross-sectional area of a flow path becomes small rapidly in the vicinity of the shielding member 630, it is possible to flow air smoothly in the main body 600A.

  The downstream inclined wall 633 is provided between the pair of side walls 631 and downstream of the upstream inclined wall 632 in the blowing direction, and is inclined with respect to the blowing direction. Specifically, the downstream inclined wall 633 is inclined so as to be gradually separated from the inner surface of the main body portion 600A (the inner surface of the second duct portion 620) toward the downstream side in the air blowing direction. Accordingly, it is possible to prevent the cross-sectional area of the flow path from rapidly increasing on the downstream side of the upstream inclined wall 632, so that air can flow smoothly in the main body portion 600A.

  The upstream inclined wall 632 and the downstream inclined wall 633 are provided between the second duct part 620 and the bottom wall part 611 of the first duct part 610, and the bottom wall part 611 of the second duct part 620 and the first duct part 610. It is arrange | positioned away from. Thereby, air can be flowed to both sides in the left-right direction of the upstream inclined wall 632 and the downstream inclined wall 633.

  Between the upstream inclined wall 632 and the downstream inclined wall 633, the 1st beam-shaped sheet metal 510 is arrange | positioned so that it may pass among these. Thereby, the disturbance of the air flow by the first beam-like sheet metal 510 can be suppressed by the upstream inclined wall 632 and the downstream inclined wall 633, so that air can flow smoothly in the main body portion 600A. ing.

  The bottom wall portion 611 of the main body portion 600A includes a first bottom wall portion 611A disposed on the most upstream side in the blowing direction, a second bottom wall portion 611B disposed on the downstream side of the first bottom wall portion 611A, It has 3rd bottom wall part 611C arrange | positioned downstream of 2 bottom wall part 611B, and 4th bottom wall part 611D arrange | positioned downstream of 3rd bottom wall part 611C. A first exhaust port 641 is formed between the first bottom wall portion 611A and the second bottom wall portion 611B, and a second exhaust gas is formed between the second bottom wall portion 611B and the third bottom wall portion 611C. A mouth 642 is formed. Further, a third exhaust port 643 is formed between the third bottom wall portion 611C and the fourth bottom wall portion 611D, and a fourth exhaust gas is formed between the fourth bottom wall portion 611D and the rear wall portion 613. A mouth 644 is formed.

  The first bottom wall portion 611A is formed in parallel in the front-rear direction (air blowing direction), and the front end of the second bottom wall portion 611B is disposed on the outer side (right side) in the left-right direction with respect to the inner surface of the first bottom wall portion 611A. It is formed so as to incline in the left-right direction as it goes rearward.

  The third bottom wall portion 611C is formed parallel to the front-rear direction, and the inner surface thereof is disposed at substantially the same position as the inner surface of the first bottom wall portion 611A and the rear end of the second bottom wall portion 611B in the left-right direction. . The front end of the fourth bottom wall portion 611D is arranged on the outer side in the left-right direction than the front end of the second bottom wall portion 611B, and is formed so as to incline in the left-right direction as it goes rearward. In addition, the rear end of the fourth bottom wall portion 611D is disposed at substantially the same position as the inner surface of the third bottom wall portion 611C in the left-right direction.

  By configuring the bottom wall portion 611 as described above, the amount of protrusion of the downstream end 641B toward the inside of the main body 600A with respect to the upstream end 641A of the first exhaust port 641 is relative to the upstream end 642A of the second exhaust port 642. The amount of protrusion of the downstream end 642B toward the inside of the main body 600A is larger. Specifically, the protrusion amount refers to a protrusion amount in a direction toward the inner side of the main body 600A and orthogonal to the front-rear direction (air blowing direction).

  As a result, even when air easily flows into the second exhaust port 642 closest to the upstream side of the shielding member 630 due to an increase in pressure near the upstream end of the shielding member 630 provided in the main body 600A, the first By making the protruding amount of the downstream end 641B of the exhaust port 641 larger than the protruding amount of the downstream end 642B of the second exhaust port 642, air easily flows into the first exhaust port 641. Therefore, the difference in the amount of air exhausted from the exhaust ports 641 and 642 can be reduced as compared with the conventional configuration in which the amount of protrusion at the downstream end of the exhaust port increases toward the downstream side.

  Further, the protruding amount of the downstream end 643B with respect to the upstream end 643A of the third exhaust port 643 is larger than the protruding amount of the downstream end 641B with respect to the upstream end 641A of the first exhaust port 641. Thereby, due to the loss due to the small cross-sectional area of the flow path by the shielding member 630, in the configuration in which air does not easily flow downstream from the shielding member 630, the third exhaust port 643 downstream from the shielding member 630 By increasing the protrusion amount of the downstream end 643B, air easily flows into the third exhaust port 643, so that the difference in the amount of air discharged from the exhaust ports 641, 642, 643 can be reduced.

  Further, the protruding amount of the downstream end 644B with respect to the upstream end 644A of the fourth exhaust port 644 is larger than the protruding amount of the downstream end 643B with respect to the upstream end 643A of the third exhaust port 643. In other words, the rear wall portion 613 extending from the bottom wall portion 611 of the first duct portion 610 to the second duct portion 620 is provided adjacent to the downstream side of the fourth exhaust port 644. As a result, air easily flows into the fourth exhaust port 644 arranged at the most downstream position, so that the difference in the amount of air discharged from the exhaust ports 641 to 644 can be reduced.

  Further, since the upstream inclined wall 632 and the downstream inclined wall 633 as the shielding portions are arranged apart from the second duct portion 620 and the bottom wall portion 611 of the first duct portion 610, the second duct portion 620 and Since the air passing between the inclined walls 632 and 633 flows smoothly toward the fourth exhaust port 644 without being obstructed by the projecting downstream end 643B of the third exhaust port 643, the fourth exhaust port 644 is provided. Air can easily flow into. As a result, the difference in the amount of air discharged from the exhaust ports 641 to 644 can be reduced. Thereby, since the difference in the amount of air guided to each charger 52 is reduced, the difference in the amount of dirt attached to each charging wire 52A can be reduced, and the difference in charging characteristics of each charger 52 is reduced. can do.

  In particular, in the present embodiment, the inclined walls 632 and 633 are disposed at positions on the outer side in the left-right direction with respect to the downstream end 643B from which the third exhaust port 643 protrudes. Therefore, the air passing between the second duct part 620 and the inclined walls 632 and 633 can flow more smoothly toward the fourth exhaust port 644.

  As shown in FIGS. 6 and 8, each of the bottom wall portions 611 </ b> A to 611 </ b> D described above forms a bottom wall of a recess 121 </ b> B that is recessed outward in the left-right direction with respect to the plate-like portion 121 of the right side frame 12. Each bottom wall portion 611A to 611D is formed with one or a plurality of reinforcing ribs 121C projecting inward in the left-right direction.

As described above, according to the present embodiment, in addition to the effects described above, the following effects can be obtained.
Since a part of the duct 600 (the first duct part 610) is formed integrally with the right side frame 12, for example, a part of the wall of the duct, the remaining wall, and the right side frame are configured as separate parts. Compared to the form, the number of parts can be reduced. Further, for example, a gap is not formed between the first duct part 610 having the exhaust ports 641 to 644 and the right side frame 12 as compared with a mode in which the wall having the exhaust port is separated from the right side frame, so that the air blowing efficiency Can be improved.

In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.
In the embodiment, air is sent out from the exhaust ports 641 to 644 toward the chargers 52. However, the present invention is not limited to this. For example, in order to cool a part of the process unit 50, the one part is used. You may comprise so that air may be sent out toward a part.

  The image forming unit is not limited to the process unit 50 configured as in the above-described embodiment, and may be configured in any manner as long as it has a photosensitive drum. For example, the image forming unit may include a toner cartridge that stores toner, a developing device that includes a developing roller, and a drum cartridge that includes a photosensitive drum.

  In the said embodiment, although the upstream inclined wall 632 and the downstream inclined wall 633 were illustrated as a shielding part, this invention is not limited to this, For example, the 1st beam-like sheet metal 510 of the said embodiment may be sufficient. That is, instead of providing the shielding member 630 as in the above embodiment, only a member for closing the groove 612A shown in FIG. 6A may be provided. Even in this case, it is possible to obtain the same effects as in the above embodiment by configuring the exhaust ports 641 to 644 as in the above embodiment.

  In the embodiment, the drawer 60 supports the plurality of process units 50, but the process unit 50 may be detachable from the drawer 60. A part of the process unit 50 such as the developing cartridge 53 may be detachable from the drawer 60. A plurality of photosensitive drums 51 may be supported integrally with the drawer 60.

  In the above embodiment, the present invention is applied to the color printer 1. However, the present invention is not limited to this, and the present invention may be applied to other image forming apparatuses such as a copying machine and a multifunction machine.

  In the above embodiment, the beam-shaped member is made of sheet metal. However, the present invention is not limited to this, and the beam-shaped member may be any member as long as it is a metal elongated member, for example, a columnar member. Good.

DESCRIPTION OF SYMBOLS 1 Color printer 50 Process part 51 Photosensitive drum 600 Duct 600A Main-body part 632 Upstream inclined wall 633 Downstream inclined wall 641 1st exhaust port 641A Upstream end 641B Downstream end 642 2nd exhaust port 642A Upstream end 642B Downstream end 643 3rd Exhaust port 644 Fourth exhaust port 700 Blower

Claims (7)

A plurality of image forming units having a photosensitive drum rotatable around a rotation axis and arranged in an arrangement direction orthogonal to the rotation axis;
A blower for blowing air;
A duct for guiding air from the blower to the plurality of image forming units, and an image forming apparatus comprising:
The duct is
A main body provided with a plurality of exhaust ports extending in the arrangement direction and for discharging air toward each of the plurality of image forming units;
A shielding part provided to shield a part of the flow path in the main body part,
The plurality of exhaust ports are a first exhaust port disposed on the upstream side in the air blowing direction with respect to the shielding portion, a downstream side in the air blowing direction with respect to the first exhaust port, and an upstream side in the air blowing direction with respect to the shielding portion. And at least a second exhaust port disposed in
The amount of protrusion toward the inside of the main body at the downstream end with respect to the upstream end of the first exhaust port is larger than the amount of protrusion toward the inside of the main body at the downstream end with respect to the upstream end of the second exhaust port. An image forming apparatus. The plurality of exhaust ports have a third exhaust port arranged on the downstream side in the blowing direction from the shielding part,
The amount of protrusion toward the inside of the main body at the downstream end with respect to the upstream end of the third exhaust port is larger than the amount of protrusion toward the inside of the main body at the downstream end with respect to the upstream end of the first exhaust port. The image forming apparatus according to claim 1. The plurality of exhaust ports have a fourth exhaust port disposed downstream of the third exhaust port in the air blowing direction,
The main body has a first wall provided with the plurality of exhaust ports, and a second wall facing the first wall,
The image forming apparatus according to claim 2, wherein the shielding unit is disposed between the first wall and the second wall so as to be separated from the first wall and the second wall. .   The said shielding part has an upstream inclined wall which inclines so that it may leave | separate gradually as it goes to the ventilation direction upstream with respect to the inner surface of the said main-body part, The Claim 1 characterized by the above-mentioned. The image forming apparatus described in 1.   The downstream inclined wall is provided on the downstream side of the upstream inclined wall in the air blowing direction, and is inclined to gradually move away from the inner surface of the main body portion toward the downstream side in the air blowing direction. Item 5. The image forming apparatus according to Item 4. A frame for supporting the plurality of image forming units and provided with the duct;
A beam-shaped member configured in a long shape and fixed to the frame in a state of passing through the duct;
The image forming apparatus according to claim 5, wherein the beam-shaped member is disposed so as to pass between the upstream inclined wall and the downstream inclined wall.   The image forming apparatus according to claim 6, wherein a first wall provided with at least the plurality of exhaust ports among the walls constituting the duct is formed integrally with the frame.

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