JP5655520B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  As an electrophotographic image forming apparatus, a tandem type color printer is known, and an image forming unit that can be pulled out from the main body casing is provided in the main body casing. The image forming unit includes a frame, and the frame includes a photosensitive drum, a scorotron charger having a charging wire, a developing cartridge, and a cleaning roller (for example, Patent Document 1). The frame holds a photosensitive drum, a scorotron charger, and the like from both sides in the rotation axis direction of the photosensitive drum.

  When a voltage is applied to the charging wire, the scorotron charger generates ions around it by discharging from the charging wire. The photoconductor drum is charged by the ions moving as an ion wind toward the photoconductor drum and hitting the photoconductor drum.

  By the way, in the scorotron type charger, if the air stays in the charger for a long time, silica or the like of the toner surface treatment agent stays in the charger. Then, the charging performance of the scorotron charger is deteriorated, for example, nonuniformity in discharge due to the silica or the like adhering to the charging wire. Further, if ozone generated during discharge stays in the scorotron charger for a long time, the photosensitive drum is deteriorated.

  Therefore, the air around the scorotron charger needs to be exhausted out of the apparatus by a fan installed in the main body casing.

JP2007-72421

  However, as shown in Patent Document 1, a photosensitive drum, a developing cartridge, and the like are arranged around the scorotron charger. Furthermore, the scorotron charger, the photosensitive drum, and the like are supported by frames from both sides in the rotation axis direction of the photosensitive drum. Therefore, the air inside the scorotron charger is not easily exhausted by the fan. Therefore, the scorotron charger has a problem that it is difficult for air to flow into the inside thereof, and the air stays in the vicinity of the scorotron charger, resulting in local wire contamination and deterioration of the photosensitive drum.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can reduce the adhesion of foreign matter to a charging wire (scorotron charger).

To achieve the above object, the present invention provides an image forming apparatus according to claim 1, comprising: a main body casing; and an image forming unit that can be pulled out from the main body casing, wherein the image forming unit includes: A photoreceptor that rotates about a rotation axis, a scorotron charger that charges the photoreceptor, and a cleaning device that is disposed upstream of the scorotron charger in the rotation direction of the photoreceptor and cleans the surface of the photoreceptor. It has a roller, and a plurality of drum units which are arranged in parallel in a direction orthogonal to the rotation axis, provided along the rotation axis direction, flowing air across in the rotational axis direction of the scorotron charger A first ventilation duct configured as described above and a first side that supports the plurality of drum units at one end in the rotational axis direction When, and a support frame having a, a second side plate for supporting the plurality of drum units at the other end of the rotation axis direction, the plurality of drum units are outside the photosensitive member and the opposite portions of the cleaning roller A cleaning roller accommodating portion for accommodating the cleaning roller therein, and an inflow hole for allowing air to flow into the first ventilation duct is formed in the first side plate. A first exhaust hole that exhausts air flowing through the scorotron charger and flowing downstream in the rotation direction of the photoconductor from between the first side plate and the second side plate, and from the scorotron charger. the air flowing upstream in the rotational direction of the photosensitive member, and a second exhaust hole for exhausting from between the first side plate and said second side plate, is formed, the cleaning roller accommodating , The air flowing in the rotational direction upstream of the photosensitive member, and having a third exhaust hole for exhausting toward the second exhaust hole is passed through the cleaning roller accommodating portion.

  The image forming apparatus according to claim 2 is the image forming apparatus according to claim 1, wherein the image forming unit includes a developing unit that develops an electrostatic latent image formed on the photoconductor. The developing unit is disposed adjacent to the scorotron charger on the downstream side in the rotation direction of the photoconductor with respect to the scorotron charger, and the first exhaust hole is viewed from the rotation axis direction of the photoconductor. And the developing unit and the scorotron charger.

The image forming apparatus according to claim 3, in the image forming apparatus according to 請 Motomeko 2, the image forming unit is provided along the rotation axis direction in the rotating direction upstream side of the photosensitive member, the scorotron the air flowing upstream in the rotational direction of the photosensitive member from the charging device comprises a second ventilation duct for evacuating the said second air hole, the second ventilation duct, characterized that you have communication with the third exhaust hole And

  The image forming apparatus according to claim 4 is the image forming apparatus according to any one of claims 1 to 3, wherein the scorotron charger is formed between a wire and the wire and the photoconductor. A frame having a first opening formed and a second opening formed to communicate with the first ventilation duct on the opposite side of the first opening across the wire; and the first ventilation The duct is formed integrally with the frame of the scorotron charger.

  The image forming apparatus according to claim 5 is the image forming apparatus according to any one of claims 1 to 4, wherein the plurality of drum units are arranged in parallel along a horizontal direction. .

  According to the image forming apparatus of the first aspect, the drum unit is supported by the first side plate and the second side plate from both sides in the rotation axis direction of the photosensitive member. The air that has entered the first ventilation duct through the inflow hole of the first side plate is sent to the entire scorotron charger. The air flowing from the scorotron charger toward the photoconductor strikes the photoconductor and is divided into two directions, that is, the upstream side in the rotation direction of the photoconductor and the downstream side in the rotation direction of the photoconductor. Air flowing downstream in the rotation direction of the photosensitive member is discharged from between the first side plate and the second side plate through the first exhaust hole of the second side plate. Then, the air flowing toward the upstream in the rotation direction of the photosensitive member is discharged from between the first side plate and the second side plate through the second exhaust hole of the second side plate. Therefore, the air that has passed through the scorotron charger is efficiently exhausted from between the first side plate and the second side plate. Therefore, the air in the first ventilation duct can efficiently pass through the scorotron charger. Accordingly, it is possible to reduce the adhesion of foreign matter to the charging wire.

  According to the image forming apparatus of the second aspect, the first exhaust hole is provided between the scorotron charger and the developing unit when viewed from the rotation axis direction of the photoreceptor. Accordingly, the air passing through the scorotron charger and flowing downstream in the rotation direction of the photoreceptor is efficiently exhausted from the first exhaust hole.

  According to the image forming apparatus of the third aspect, the image forming unit includes the second ventilation duct. Thereby, the air flowing upstream in the rotation direction of the photoconductor is well exhausted from between the first side plate and the second side plate.

  According to the image forming apparatus of claim 4, the frame constituting the scorotron charger forms the first ventilation duct, so that it is not necessary to separately provide the first ventilation duct, and the configuration of the image forming apparatus is the same. It can be simplified.

  According to the image forming apparatus of the fifth aspect, since the drum units are arranged in parallel along the horizontal direction, the image forming apparatus can be downsized in the vertical direction.

It is the sectional side view which looked at the color printer from the left side. FIG. 4 is an enlarged side sectional view of the developing unit 18M, the drum unit 17M, and the developing unit 18C as viewed from the left side. FIG. 6 is an enlarged side sectional view of the drum unit 17M, the developing unit 18M, and the developing unit 18C as viewed from the right side. FIG. 3 is a schematic diagram showing how air flows between a pair of side plates 20 and 21. In FIG. 3, it is the figure which showed how the air flowed with the arrow. It is the expanded sectional side view which looked at the drum unit 17M which concerns on the modification, the developing unit 18M, and the developing unit 18C from the right side.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate.

<Overall configuration of color printer>
FIG. 1 is a schematic diagram of a side cross section of a color printer 1 as an example of an image forming apparatus. The color printer 1 is a tandem type color printer.

  As shown in FIG. 1, the color printer 1 includes a paper cassette 10, a scanner unit 11, an image forming unit 12, a transfer unit 13 and a fixing unit 14 in a main body casing 2. The main body casing 2 includes a paper discharge tray 28 at an upper portion thereof. The main casing 2 includes a front cover 4 provided on one side wall of the main casing 2 so as to be opened and closed. The image forming unit 12 can be pulled out of the main casing 2 by opening the front cover 4.

  In the following description, the side where the front cover is provided (the right side in FIG. 1) is the front side, and the opposite side (the left side in FIG. 1) is the rear side. Further, when the color printer 1 is viewed from the front side, the left and right reference is used.

  The paper feed cassette 10 is disposed at the bottom of the main casing 2. The paper P stored in the paper feed cassette 10 is conveyed toward the transfer unit 13 and the image forming unit 12 by various rollers.

  The scanner unit 11 is disposed on the upper side of the main body casing 2. Although not shown, the scanner unit 11 includes a laser light emitting unit, a polygon mirror, a plurality of lenses, and a reflecting mirror. The scanner unit 11 irradiates each photosensitive drum 5 as an example of a photosensitive member of the image forming unit 12 with laser light corresponding to each color of cyan, magenta, yellow, and black.

  The image forming unit 12 is disposed between the scanner unit 11 and the transfer unit 13 and has a drum unit having a photosensitive drum 5 as an example of a photoconductor arranged in parallel along the conveyance direction (front-rear direction) of the paper P. 17, a developing unit 18, and a support frame 19 that supports the drum unit 17 and the developing unit 18.

  The drum unit 17 includes a photosensitive drum 5, a scorotron charger 6, and a cleaning roller 7.

  The photosensitive drum 5 is provided to be rotatable about a rotation axis extending in the left-right direction. The scorotron charger 6 is provided along the rotational axis direction of the photosensitive drum 5 at a predetermined interval so as not to contact the photosensitive drum 5.

  The cleaning roller 7 for cleaning the surface of the photosensitive drum 5 is disposed adjacent to the scorotron charger 6 on the downstream side in the rotation direction of the photosensitive drum 5 with respect to the scorotron charger 6.

  The support frame 19 includes a left side plate 20 as an example of a first side plate located on the left side when viewed from the front, and a right side plate 21 as an example of a second side plate located on the right side when viewed from the front. The pair of side plates 20 and 21 supports the photosensitive drum 5, the scorotron charger 6 and the cleaning roller 7 so as to be sandwiched from both sides in the left-right direction. In FIG. 1, only the left side plate 20 is shown for convenience.

  The developing unit 18 includes a toner box 23 that stores toner therein, a developing roller 24, and a supply roller 25. The toner box 23 has a box shape. The developing roller 24 is held at the lower end of the toner box 23 with a part of the peripheral surface exposed to the outside. The supply roller 25 is in contact with the developing roller 24 above the developing roller 24.

  In the image forming unit 12 configured as described above, the surface of the photosensitive drum 5 is uniformly positively charged by the scorotron charger 6 and then exposed by high-speed scanning of the laser light from the scanner unit 11. Thereby, the potential of the exposed part is lowered, and an electrostatic latent image based on the image data is formed.

  The toner in the toner box 23 is supplied to the electrostatic latent image on the photosensitive drum 5 by the supply roller 25 and the developing roller 24. Then, the toner is selectively carried on the surface of the photosensitive drum 5 to be visualized, whereby a toner image is formed by reversal development.

  The transfer unit 13 includes a conveyance belt 26 and a transfer roller 27. The conveyor belt 26 is disposed to face the photosensitive drum 5. The transfer roller 27 is disposed inside the conveyance belt 26 so as to sandwich the conveyance belt 26 between each photosensitive drum 5.

  The paper P transported on the transport belt 26 sequentially passes between the transport belt 26 and the photosensitive drum 5 as the transport belt 26 travels. The toner image on the surface of the photosensitive drum 5 is transferred to the paper P by the transfer bias applied to the transfer roller 27 when facing the paper P.

  The fixing unit 14 includes a heating roller 14A and a pressure roller 14B. The fixing unit 14 heats and fixes the toner image on the paper P by feeding the paper P while sandwiching it between the heating roller 14A and the pressure roller 14B.

  The paper discharge tray 28 stacks the paper P discharged from the fixing unit 14.

  In the drawing, for the drum unit 17 and the developing unit 18, K (black), Y (yellow), M (magenta), and C (cyan) representing each color are added to the end of the reference numerals.

<Description of the Characteristic Part of the Present Embodiment>
Next, the characteristic part of this embodiment is demonstrated using FIG. 2, FIG.

  FIG. 2 is an enlarged cross-sectional side view of the drum unit 17M, the developing unit 18M, and the developing unit 18C as viewed from the left side.

  FIG. 3 is an enlarged side sectional view of the drum unit 17M, the developing unit 18M, and the developing unit 18M as viewed from the right side.

  Here, the description will be given focusing on the developing unit 18M and the drum unit 17M.

  As shown in FIG. 2, the drum unit 17 </ b> M includes a photosensitive drum 5, a scorotron charger 6, a cleaning roller 7, and a cleaning roller storage unit 40 that stores the cleaning roller 7 therein.

  As shown in FIG. 2, the scorotron charger 6 includes wires 6 </ b> A, a grid 6 </ b> B, and a frame body 30.

  As shown in FIG. 2, the frame 30 includes a first grid support piece 31 </ b> A, a second grid support piece 31 </ b> B, a first duct wall 32, and a second duct wall 33.

  As shown in FIG. 2, the first grid support piece 31 </ b> A and the second grid support piece 31 </ b> B are plate-like members, arranged to face each other with a space therebetween, and support the grid 6 </ b> B on the inner surface. . The pair of grid support pieces 31A and 31B form a first opening 34 between the photosensitive drum 5 and the wire 6A. Further, the pair of grid support pieces 31A and 31B has a second opening 39 formed along the wire 6A on the opposite side of the photosensitive drum 5 with the wire 6A interposed therebetween. The second opening 39 is formed by the first grid wall 32 and the second duct wall 33 formed by the first grid support piece 31 </ b> A and the second grid support piece 31 </ b> B and accommodating the wire 6 </ b> A. It is formed between the first ventilation duct 38.

  As shown in FIG. 2, the first grid support piece 31 </ b> A is disposed between the wire 6 </ b> A and the cleaning roller 7 on the upstream side in the rotation direction of the photosensitive drum 5 with respect to the wire 6 </ b> A. The end of the first grid support piece 31 </ b> A on the photosensitive drum 5 side is arranged at a predetermined interval so as not to contact the cleaning roller 7.

  As shown in FIG. 2, the first duct wall 32 has a base portion 32A and a bent portion 32B. The base 32A extends upward from the end of the second grid support piece 31B on the photosensitive drum 5 side. The base portion 32 </ b> A is formed along the rotation axis direction of the photosensitive drum 5. The bent portion 32B bends obliquely rearward and upward from the upper end portion of the base portion 32A. The bent portion 32B extends toward the developing unit 18C.

  As shown in FIG. 2, the second duct wall 33 has a bent portion 32 </ b> B and an upper end portion of the second grid support piece 31 </ b> A, and is provided along the rotation axis direction of the photosensitive drum 5.

  As shown in FIG. 2, the first ventilation duct 38 is provided by the first duct wall 32 and the second duct wall 33 so that air flows through the scorotron charger 6 in the direction of the rotation axis of the photosensitive drum 5. Yes.

  As shown in FIG. 2, the cleaning roller housing portion 40 houses the cleaning roller 7 so that the cleaning roller 7 is exposed to the outside facing the photosensitive drum 5. The cleaning roller accommodating portion 40 is opposed to the toner box 23 of another adjacent developing unit 18, that is, the toner box 23 C of the developing unit 18 C with a space therebetween, the upper wall 41 along the toner box 23 C, and the cleaning roller 7. And a lower wall 42 covering the lower side.

  As shown in FIG. 2, the first grid support piece 31 </ b> A and the upper wall 41 are arranged above the cleaning roller 7 with a space therebetween, so that the drum unit extends along the rotational axis direction of the photosensitive drum 5. An exhaust hole 50 is formed.

  Further, an air passage 51 is formed between the upper wall 41 and the lower end portion of the toner box 23C of the developing unit 18C by disposing the developing unit 18M and the developing unit 18C at an interval in the front-rear direction. Yes.

  As shown in FIG. 2, a first exhaust hole 44 and a second exhaust hole 45 are formed in the right side plate 21. Specifically, the first exhaust hole 44 is provided above the photosensitive drum 5 as seen from the rotation axis direction of the photosensitive drum 5 and penetrating between the developing unit 18M and the scorotron charger 6. ing.

  The second exhaust hole 45 is provided adjacent to the rear side with respect to the cleaning roller accommodating portion 40 as viewed from the rotational axis direction of the photosensitive drum 5 and penetrating in the rotational axis direction of the photosensitive drum 5. .

  For example, in the drum unit 17M, the drum unit 17C is disposed adjacent to the rear. The second exhaust hole 45 is provided between the cleaning roller accommodating portion 40 of the drum unit 17M and the lower end portion of the toner box 23C of the developing unit 18C when viewed from the rotational axis direction of the photosensitive drum 5.

  As shown in FIG. 3, the left side plate 20 is provided with an inflow hole 43 that faces the first ventilation duct 38 in the rotational axis direction of the photosensitive drum 5 and penetrates in the rotational axis direction of the photosensitive drum 5. Air flows into the first ventilation duct 38 through the inflow hole 43.

  The inflow holes 43 are provided in the left side plate 20 so as to be adjacent to the first ventilation ducts 38 corresponding to the respective drum units 17 in the rotation axis direction of the photosensitive drum 5.

  The first exhaust hole 44 and the second exhaust hole 45 are provided in the right side plate 21 with respect to the drum unit 17 and the developing unit 18 in the positional relationship described above. Specifically, the first exhaust hole 44 is provided between the toner box 23 and the base portion 32 </ b> A of each developing unit 18 when viewed from the rotation axis direction of the photosensitive drum 5. The second exhaust hole 45 is provided on the side opposite to the photosensitive drum 5 with the cleaning roller 7 provided in each drum unit 17 interposed therebetween.

  Next, how air flows in the color printer 1 will be described with reference to FIGS. 4 and 5. FIG. 4 is a schematic diagram showing how air flows between the pair of side plates 20 and 21. FIG. 5 is a diagram showing how the air flows in FIG. 3 by arrows.

  FIG. 4 shows the drum unit 17M, the drum unit 17C, and a pair of side plates 20 and 21 that hold the drum unit 17. In FIG. 4, the first ventilation duct 38 and the developing unit 18 are omitted for simplification of the drawing.

  The air in the color printer 1 is moved from the front side to the rear side between the left side plate 20 and the right side plate 21 and the main body casing 2 by the exhaust fan 100. The exhaust fan 100 is provided to the right of the lower rear side of the main casing 2. Accordingly, the air moving outside the left side plate 20 enters the first ventilation duct 38 via the inflow hole 43 and is blown onto the wire 6A while proceeding along the rotational axis direction of the photosensitive drum 5 (FIG. 5). In FIG. 4, this air flow is indicated by an arrow X.

  The air blown onto the wire 6A hits the photosensitive drum 5, and is divided into an upstream side and a downstream side in the rotational direction of the photosensitive drum 5 with respect to the wire 6A. In FIG. 4, the air flowing on the downstream side in the rotation direction of the photosensitive drum 5 with respect to the wire 6 </ b> A is represented by an arrow Y. The air Y travels toward the first exhaust hole 44 along the rotational axis direction of the photosensitive drum 5 while traveling on the surface of the photosensitive drum 5 downstream in the rotational direction of the photosensitive drum 5.

  In FIG. 4, the air flowing to the upstream side in the rotation direction of the photosensitive drum 5 with respect to the wire 6 </ b> A is represented by an arrow Z. The air Z travels on the surface of the photosensitive drum 5 to the upstream side in the rotation direction of the photosensitive drum 5, and travels above the cleaning roller 7 from the front side toward the rear side. At the same time, the air Z advances toward the second exhaust hole 45 along the rotation axis direction of the photosensitive drum 5.

  The air Y and Z separated into the upstream side and the downstream side in the rotation direction of the photosensitive drum 5 with respect to the wire 6A is passed through the first exhaust hole 44 and the second exhaust hole 45 formed in the right side plate 21. The air is exhausted between the left side plate 20 and the right side plate 21.

  Next, how air flows between the pair of side plates 20 and 21 will be described with reference to FIG.

  As shown in FIG. 4, the air that has entered the first duct 38 through the second opening 43 travels along the rotational axis direction of the photosensitive drum 5, and passes through the blow hole 39 to form the scorotron charging. It enters the inside of the vessel 6 and sprays it on the wire 6A.

  The air Y branched to the downstream side in the rotation direction of the photosensitive drum 5 with respect to the scorotron charger 6 passes between the second grid support piece 31B and the photosensitive drum 5 from the front toward the rear. The air Y travels upward between the scorotron charger 6 and the developing cartridge 8 and is exhausted from between the left side plate 20 and the right side plate 21 through the first exhaust hole 44.

  The air Z branched to the upstream side in the rotation direction of the photosensitive drum 5 passes between the first grid support wall 31 </ b> A and the cleaning roller 7 and enters the air passage 51 through the third exhaust hole 50. The air Z that has entered the ventilation path 51 travels downward between the upper wall 41 and the adjacent developing cartridge 8, and is exhausted from between the right side plate 21 and the left side plate 20 through the second exhaust hole 45. .

  Then, the air exhausted from between the right side plate 21 and the left side plate 20 through the first exhaust hole 44 and the second exhaust hole 45 proceeds toward the front side outside the right side plate 21, and the exhaust fan 100 Then, the air is exhausted outside the color printer 1.

  With the above configuration, the color printer 1 according to the present embodiment can obtain the following effects.

  The drum unit 17 is supported by the left side plate 20 and the right side plate 21 from both sides in the rotational axis direction of the photosensitive drum 5. The air that has entered the first ventilation duct 38 through the inflow hole 43 of the left side plate 20 is sent to the entire scorotron charger 6. The air flowing from the scorotron charger 6 toward the photosensitive drum 5 hits the photosensitive drum 5 and is divided into two directions, that is, an upstream side in the rotational direction of the photosensitive drum 5 and a downstream side in the rotational direction of the photosensitive drum 5. Air flowing downstream in the rotation direction of the photosensitive drum 5 is discharged from between the right side plate 21 and the left side plate 20 through the first exhaust hole 44 of the right side plate 21. Then, the air flowing toward the upstream in the rotation direction of the photosensitive drum 5 is discharged from between the left side plate 20 and the right side plate 21 through the second exhaust hole 45 of the right side plate 21. Therefore, the air that has passed through the scorotron charger 6 is efficiently exhausted from between the left side plate 20 and the right side plate 21. Therefore, the air in the first ventilation duct 38 can efficiently pass through the scorotron charger 6. Therefore, it can reduce that a foreign material adheres to the wire 6A.

  The first exhaust hole 44 is formed between the developing unit 18 and the scorotron charger 6. As a result, the air flowing downstream in the rotational direction of the photosensitive drum 5 with respect to the scorotron charger 6 can be efficiently exhausted from the first exhaust hole 44.

  The first ventilation duct 38 is formed integrally with the frame body 30. Therefore, it is not necessary to provide the first ventilation duct 38 separately, and the configuration of the color printer 1 can be simplified.

  Further, since the plurality of drum units 17 are arranged along the horizontal direction, the color printer 1 can be downsized in the vertical direction.

<Modification>
Next, a modification will be described with reference to FIG. Parts having the same configurations as those in the above embodiment are given the same numbers, and description thereof is omitted. Also in the description of the modified example, the description will be given focusing on the drum unit 17M and the developing unit 18M.

  FIG. 6 is an enlarged cross-sectional side view of the drum unit 17M, the developing unit 18M, and the developing unit 18M according to the modification as seen from the right side.

  As shown in FIG. 6, the drum unit 17 according to the modification includes a second ventilation duct 60 that is provided adjacent to the cleaning roller accommodating portion 40 and guides air to the second exhaust hole 45. The second ventilation duct 60 is provided adjacent to the installation plate 61 on the opposite side of the cleaning roller 7 with the installation plate 61 interposed therebetween. The frame body 30 includes a first film 70 and a second film 71.

  Specifically, the cleaning roller accommodating portion 40 has an erection plate 61 for erection of the upper wall 41 and the lower wall 42. The erection plate 61 is provided along the rotation axis direction of the cleaning roller 7. A third exhaust hole 80 is formed in the installation plate 61 along the rotation axis direction of the cleaning roller 7 to allow the air branched through the scorotron charger 6 to flow downstream in the rotation direction of the photosensitive drum 5. Has been.

  The second ventilation duct 60 is provided between the pair of side plates 20 and 21 along the rotation axis direction of the cleaning roller 7. The second ventilation duct 60 is provided adjacent to the second exhaust hole 45 provided in the right side plate 21 in the rotation axis direction of the photosensitive drum 5. The second ventilation duct 60 is provided for each drum unit 17.

  Further, the positional relationship between the inflow hole 43 and the first ventilation duct 38 in the modification is the same as that shown in FIG.

  The 1st film 70 is affixed with respect to the upper side edge part of 31 A of 1st grid support pieces. The first film 70 extends from the upper end portion of the first grid support piece 31A toward the adjacent developing unit 18C, and the upper end portion contacts the toner box 23C of the developing unit 18C.

  The 2nd film 71 is affixed with respect to the bending part 32B. The second film 71 extends from the upper end portion of the bent portion 32B toward the adjacent developing unit 18C, and the upper end portion contacts the toner box 23C.

  The first ventilation duct 38 is provided so as to send air to the entire scorotron charger 6 by the first duct wall 32, a part of the toner box 23C, the first film 70, and a part of the second film 71. It has been. By forming the first ventilation duct 38 in this way, the air that passes through the scorotron charger 6 and flows downstream in the rotation direction of the photosensitive drum 5 toward the first exhaust hole 44 is transferred to the toner box 23C and the drum unit. It can reduce flowing between the frame body 30 of 17M. Therefore, the air that passes through the scorotron charger 6 and flows downstream in the rotation direction of the photosensitive drum 5 is efficiently exhausted from the first exhaust hole 44.

  From the configuration as described above, the air that has passed through the scorotron charger 6 and branched to the upstream side in the rotation direction of the photosensitive drum 5 passes through the third exhaust hole 50 provided in the installation plate 61 to the second ventilation. Guided into the duct 60. The air guided into the second ventilation duct 60 proceeds toward the left side plate 20 along the rotational axis direction of the cleaning roller 7 through the inside of the duct. The air in the second ventilation duct 60 is exhausted from the second ventilation duct 60 through the second exhaust hole 45.

  Thus, by providing the second ventilation duct 60, the air that passes through the scorotron charger 6 and flows upstream in the rotation direction of the photosensitive drum 5 with respect to the scorotron charger 6 is more efficiently left side plate. The air is exhausted between 20 and the right side plate 21.

  Therefore, the stagnation of air inside the scorotron charger 6 can be reduced, and the adhesion of foreign matter to the wire 6A can be reduced.

  In the above embodiment, the cleaning roller 7 is used to remove foreign matter on the photosensitive drum 5. However, instead of the cleaning roller 7, a brush-like one may be used.

  In the above-described embodiment, in the color printer 1, the photosensitive drum 5 is arranged along the horizontal direction, but the photosensitive drum 5 may be arranged along the vertical direction.

5 Photosensitive drum 7 Cleaning roller 6 Charger 17 Drum unit 18 Development unit 20 Left side plate 21 Right side plate 40 Housing portion 43 Inflow hole 44 First exhaust hole 45 Second exhaust hole 80 Third exhaust hole 60 Second ventilation duct

Claims (8)

A body casing;
An image forming apparatus including an image forming unit that can be pulled out with respect to the main body casing,
The image forming unit includes:
A photoconductor that rotates about a rotation axis, a scorotron charger that charges the photoconductor, and a cleaning roller that is disposed upstream of the scorotron charger in the rotation direction of the photoconductor and cleans the surface of the photoconductor And a plurality of drum units arranged in parallel in a direction orthogonal to the rotation axis, and
A first ventilation duct that is provided along the rotational axis direction and configured to flow air throughout the rotational axis direction of the scorotron charger;
A support frame having a first side plate that supports the plurality of drum units at one end in the rotation axis direction, and a second side plate that supports the plurality of drum units at the other end in the rotation axis direction,
The plurality of drum units include a cleaning roller housing portion that houses the cleaning roller so that a portion of the cleaning roller facing the photoconductor is exposed to the outside.
In the first side plate,
An inflow hole for allowing air to flow into the first ventilation duct is formed,
In the second side plate,
A first exhaust hole for exhausting air flowing through the scorotron charger and flowing downstream in the rotational direction of the photoreceptor from between the first side plate and the second side plate;
A second exhaust hole for exhausting air flowing from the scorotron charger to the upstream side in the rotation direction of the photoconductor from between the first side plate and the second side plate ;
The cleaning roller accommodating portion has a third exhaust hole that exhausts air flowing upstream in the rotation direction of the photosensitive member through the cleaning roller accommodating portion and exhausting the air toward the second exhaust hole. Image forming apparatus. The image forming unit has a developing unit for developing an electrostatic latent image formed on the photoconductor,
The developing unit is disposed adjacent to the scorotron charger on the downstream side in the rotation direction of the photoconductor with respect to the scorotron charger.
2. The image forming apparatus according to claim 1, wherein the first exhaust hole is disposed between the developing unit and the scorotron charger as viewed from the rotation axis direction of the photosensitive member. The image forming unit is provided along the rotation axis direction on the upstream side in the rotation direction of the photoconductor, and exhausts air flowing from the scorotron charger to the upstream side in the rotation direction of the photoconductor to the second exhaust hole. With a second ventilation duct ,
The second ventilation duct, the image forming apparatus according to 請 Motomeko 2 you, characterized in that in communication with the third exhaust hole. The scorotron charger is
Wire,
A first opening formed between the wire and the photosensitive member, and a second opening formed to communicate with the first ventilation duct on the opposite side of the first opening with the wire interposed therebetween And a frame having
The image forming apparatus according to claim 1, wherein the first ventilation duct is formed integrally with the frame body of the scorotron charger.   The image forming apparatus according to claim 1, wherein the plurality of drum units are arranged in parallel along a horizontal direction.   The image forming apparatus according to claim 3, wherein the second ventilation duct is adjacent to the second exhaust hole in the rotation axis direction.   The image forming apparatus according to claim 6, wherein the second ventilation duct is supported by the cleaning roller housing portion.   Further comprising a conveyor belt that faces the plurality of drum units and moves in an orthogonal direction that is orthogonal to the rotation axis;
  The plurality of drum units include a first drum unit and a second drum unit adjacent to the first drum unit on the downstream side in the moving direction of the transport belt with respect to the first drum unit,
  The developing unit has a first developing unit corresponding to the first drum unit, and a second developing unit corresponding to the second drum unit,
  The second developing unit is disposed facing the cleaning roller accommodating portion of the first drum unit in the orthogonal direction,
  The image forming apparatus according to claim 6, wherein the second ventilation duct is disposed between the cleaning roller accommodating portion of the first drum unit and the second developing unit in the orthogonal direction.