JP2017067815A - Air duct, blower, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air duct or the like capable of preventing an air containing an electric discharge product generated by a corona discharger from flowing out through a gap between a side surface part on the upper stream side in a rotation direction of an electric discharge object rotation product among cover members of the corona discharger and a surface of the electric discharge object rotation product.SOLUTION: An air duct includes: a body passage part constituted by an introduction passage part, a first bent passage part, and a second bent passage part bent downward from the terminal end of the first bent passage part and provided with an outlet facing an opening part of a cover member of a corona discharger; a first suppression part having a structure in a state that a portion of a passage space of the first bent passage part is crossed to shut it off and allowing a gap to exist at the lower end; a second suppression part having the structure in a state that the outlet is sealed with an air permeable member; and a branch passage part that branches from a region extending along a lateral direction of a first control part at a surface part facing a gap of the first control part from among inner wall surfaces of the passage space of the first bent passage part and having a separation passage part extending to a position approaching the surface of an electric discharge object rotation product at the outside of a side surface portion among the cover members.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a blower tube, a blower, and an image forming apparatus.

  In recent years, the present applicant has made proposals related to the following blower devices and the like.

  For example, as a blower, it is arranged in a state where it faces a longitudinal portion of an elongated target structure to be blown with air taken in from the blower and air taken in from the blower. An outlet that flows out along a direction orthogonal to the direction, and a main body portion in which a passage space for flowing air is formed between the inlet and the outlet, and the outlet is formed on the target structure. A direction in which air flows in the passage space of the main body portion of the blast pipe that is formed in a long opening shape parallel to the longitudinal portion, and the inlet and the outlet are formed in different opening shapes. A plurality of restraining portions for restraining air flow, and the most downstream restraining portion provided at the most downstream portion of the restraining portion in the direction of flowing air in the passage space, Proposes a blower using a blowing tube a channel space downstream of the site plurality of ventilation portions are formed so as to be in a state closes breathable member dotted (Patent Document 1). Patent Document 1 exemplifies, for example, a corona discharger as a target structure.

JP 2013-88731 A

  The present invention relates to a side portion on the upstream side in the rotation direction of a rotating object to be discharged that receives corona discharge among the covering members of the corona discharger, and a surface of the rotating object to be discharged. Outflowing through the gap between the airflow and the airflow can be suppressed while blowing air with reduced unevenness of the wind speed toward the opening having a long shape in one direction of the covering member of the corona discharger. A blower tube is provided, and a blower and an image forming apparatus using the blower tube are provided.

The blast tube of this invention (A1)
From an introduction passage portion having a passage space provided at one end with an inlet for taking in air, a first bending passage portion having a passage space that bends in the lateral direction from the middle of the introduction passage portion, and an end of the first bending passage portion An outlet having an opening shape that extends in a state facing a long air inlet opening in one direction in a cover member of a corona discharger that is bent downward and is blown with air taken in from the inlet at the end bent downward A main body passage portion constituted by a second bending passage portion having a passage space provided with;
A first suppression unit that blocks and crosses a part of the passage space of the first bending passage unit and suppresses the flow of air as a structure in which a gap exists at the lower end;
A second suppression unit that suppresses the flow of air as a structure in which the outlet is closed with a breathable member interspersed with a plurality of ventilation units;
Of the inner wall surface constituting the passage space of the first bending passage portion, the surface portion facing the gap of the first control portion or the surface portion after passing through the gap, in the direction crossing the first control portion. Branching from a portion extending along the corona discharger, the outer surface of the corona discharger that is on the upstream side in the rotation direction of the discharge target rotation subject to corona discharge by the corona discharger, the discharge target rotation object A branch passage portion having a branch passage space extending to a position approaching the surface of
It is equipped with.

The blast tube of this invention (A2) is the blast tube of the above-mentioned invention A1, wherein the branch passage section has an opening at the end facing at least the surface of the rotating object to be discharged in the shunt passage space, and the corona discharger. The cover member is provided so as to exist at a position away from the side surface portion on the upstream side in the rotation direction of the discharge object rotation object.
The blast tube of this invention (A3) is the blast tube of the above invention A1, wherein at least a part of the branch passage space is formed of the rotating object to be discharged among the covering members of the corona discharger. It is comprised and provided by the side part which becomes a rotation direction upstream.

In the blast tube of the present invention (A4), in the blast tube of any one of the above inventions A1 to A3, the branch passage portion has an opening at the end facing at least the surface of the rotating object to be discharged in the shunt passage space. The cover member of the corona discharger is provided so as to be present at the end of a bent portion that is bent toward the side closer to the side surface portion on the upstream side in the rotation direction of the rotating object to be discharged.
The blast tube of this invention (A5) is a curved surface in which the surface portion when passing through the corona discharger is at least a constant curvature as the rotating object to be discharged in the blast tube of any of the inventions A1 to A4. When the rotating object to be discharged is applied, the branch passage portion includes a lower end of a side surface portion on the upstream side in the rotation direction of the rotating object to be discharged and a portion of the shunt passage space and the rotating object to be discharged. The distance to the surface is shorter than or equal to the distance between the lower end of the side surface portion on the downstream side in the rotation direction of the discharge target rotating object and the surface of the discharge target rotating object in the portion constituting the shunt passage space. It is provided to be a value.

  The blower of this invention (B) is provided with the air blower which sends air, and the air blow pipe in any one of said invention A1 to A5 which takes in the air sent from the said air blower.

  The image forming apparatus according to the present invention (C) includes a corona discharger having a covering member provided with an air inflow opening having a long shape in one direction in which air is to be blown, and a longitudinal direction of the covering member of the corona discharger. A rotating object to be discharged that receives a corona discharge by the corona discharger, and a blower that blows air to an air inflow opening in a cover member of the corona discharger. The air blower is composed of the air blower of the invention B.

  According to the blower tube of the invention A1, the air including the discharge product generated in the corona discharger is a side surface portion on the upstream side in the rotation direction of the rotating object to be discharged that receives corona discharge among the covering members of the corona discharger. The air flowing out through the gap between the surface of the rotating object to be discharged and the blowing of air with reduced unevenness of the wind speed toward the one-way opening of the corona discharger covering member was maintained. It can be suppressed as it is.

In the blast pipe of the invention A2, the effect of the invention A1 can be obtained more reliably than in the case where the branch passage portion is provided with a configuration different from that of the branch passage portion in the invention A2.
In the blast tube of the invention A3, the branch passage portion can be easily provided as compared with the case where the branch passage portion is provided in a configuration different from that of the branch passage portion in the invention A3.

In the blast pipe of the invention A4, the effect of the invention A1 can be obtained more reliably than in the case where the branch passage portion is provided with a configuration different from that of the branch passage portion in the invention A4.
In the blast tube of the invention A5, compared with the case where the branch passage portion is configured differently from the branch passage portion in the invention A5, the surface portion when passing through the corona discharger becomes a curved surface having a constant curvature. Even when the target rotating object is applied, the effect of the invention A1 can be reliably obtained.

  According to the blower device of the invention B, in the blower tube, the air containing the discharge product generated by the corona discharger is upstream of the rotating object to be discharged subjected to the corona discharge among the covering members of the corona discharger. The air flowing out through the gap between the side portion to be turned and the surface of the rotating object to be discharged is blown into the opening having a long shape in one direction of the covering member of the corona discharger, and air with reduced wind speed is blown. It can be suppressed while keeping on.

  According to the image forming apparatus of the invention C, the air containing the discharge product generated in the corona discharger in the blower tube of the blower is the discharge target rotating object that receives the corona discharge among the covering members of the corona discharger. Unevenness of the wind speed is reduced by flowing out through the gap between the side surface portion on the upstream side in the rotation direction and the surface of the rotating object to be discharged toward the opening having a long shape in one direction of the covering member of the corona discharger. It can be suppressed while maintaining the blowing of air.

1 is an explanatory diagram illustrating an outline of an image forming apparatus using a blower according to Embodiment 1 and the like. FIG. 2 is a perspective view illustrating an outline of a charging device including a corona discharger provided in the image forming apparatus of FIG. 1. It is a perspective view which shows the outline | summary of the air blower applied to the charging device of FIG. It is a cross-sectional explanatory drawing which follows the QQ line of the air blower of FIG. It is the schematic which shows a state when the air blower of FIG. 3 is seen from upper direction. It is the schematic which shows a state when the air blower of FIG. 3 is seen from the downward direction (an exit and a branch passage part). It is explanatory drawing which shows the structure of the air blower (mainly air duct) of FIG. 3 in detail. It is explanatory drawing which expands and shows the structure of the principal part (branch passage part) of the blast pipe of FIG. It is explanatory drawing which shows the operation state etc. of the air blower of FIG. It is a graph which shows the result of the test regarding the characteristic performance of each blast pipe. It is sectional explanatory drawing which shows the outline | summary of the air blower (blower pipe) which concerns on Embodiment 2. FIG. It is explanatory drawing which shows the operation state of the air blower of FIG. It is sectional explanatory drawing which shows the other structural example of a blast tube. It is sectional explanatory drawing which shows the other structural example of the branch channel | path part in an air duct.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described with reference to the accompanying drawings.

[Embodiment 1]
1 to 4 show a blower duct, which is an example of a blower pipe according to Embodiment 1, and a blower and an image forming apparatus using the blower duct. FIG. 1 shows an outline of the image forming apparatus, FIG. 2 shows a charging device as an example of a corona discharger to which air is blown by the blower duct or blower, and FIG. 3 shows an outline of the blower duct or blower. FIG. 4 shows a cross section of the air duct and the like.

<Configuration of image forming apparatus>
As shown in FIG. 1, the image forming apparatus 1 forms a toner image composed of toner as a developer in an internal space of a casing 10 composed of a support frame, an exterior cover, and the like. As an example, an image forming unit 20 for transferring to the recording paper 9, a paper feeding device 30 for storing and conveying the recording paper 9 supplied to the image forming unit 20, and a toner image formed by the image forming unit 20 are recorded on the recording paper A fixing device 35 and the like for fixing to 9 are arranged.

  The image forming unit 20 is configured using, for example, a known electrophotographic method. The image forming unit 20 according to the first embodiment includes a photosensitive drum 21 that is rotationally driven in a direction indicated by an arrow A, a charging device 4 that charges a peripheral surface serving as an image forming area of the photosensitive drum 21 to a required potential, An exposure device 23 that forms an electrostatic latent image by irradiating light (dotted line with arrows) based on image information (signal) input from the outside onto the charged peripheral surface of the photosensitive drum 21 and the electrostatic latent image Is developed with toner to form a toner image, a transfer device 25 for transferring the toner image from the photosensitive drum 21 to the recording paper 9, toner remaining on the peripheral surface of the photosensitive drum 21 after transfer, etc. And a cleaning device 26 that removes unnecessary materials and cleans them.

  Among these, as the charging device 4, a charging device configured using a corona discharger is used. As shown in FIG. 2 and the like, the charging device 4 composed of this corona discharger is constituted by a so-called scorotron type corona discharger.

  That is, the charging device 4 is an enclosing member having an external shape having a rectangular top plate 40a and side plates 40b and 40c hanging downward from a long side portion extending along the longitudinal direction B of the top plate 40a. The shield case 40 as an example, two end support members (not shown) attached to both end portions (short side portions) in the longitudinal direction B of the shield case 40, and the shield case between the two end support members Two corona discharge wires 41A and 41B that exist in a long internal space along the longitudinal direction B of 40 and are attached so as to be stretched in a substantially parallel state, and a discharge opening 44 on the lower surface of the shield case 40. In addition, a porous group attached to the corona discharge wires 41A and 41B and the peripheral surface of the photosensitive drum 21 so as to substantially cover the lower opening 44. Head electrode and a (field adjustment plate) 42. Reference numeral 40 d shown in FIG. 4 and the like is a partition plate that divides a space in which the two corona discharge wires 41 </ b> A and 41 </ b> B are arranged along the longitudinal direction B of the shield case 40. The opening 44 for discharge is formed so that the opening shape may become a rectangle.

  Further, the charging device 4 is in a state in which the two corona discharge wires 41A and 41B are opposed to the peripheral surface of the photosensitive drum 21 with a predetermined interval (for example, a discharge gap) and the rotation axis of the photosensitive drum 21. It is arranged so as to exist at least in a state facing the image forming region along the direction. Further, when the charging device 4 is in an image forming operation, a charging voltage is supplied to each of the corona discharge wires 41A and 41B (between the photosensitive drum 21) from a power supply device (not shown). .

  Further, as the charging device 4 is used, the corona discharge wires 41A and 41B and the grid electrode 42 are coated with substances (such as paper dust of the recording paper 9, discharge products generated by corona discharge, and external additives of toner). Unnecessary materials) may adhere and become contaminated. As a result, corona discharge may not be performed sufficiently or uniformly, and charging defects such as uneven charging may occur. For this reason, the charging device 4 blows air toward the discharge wires 41 and 41B and the grid electrode 42 for the purpose of preventing or suppressing the attachment of unnecessary materials to the corona discharge wires 41A and 41B and the grid electrode 42. An air blower 5 for turning on is also provided. Further, an air inflow opening 43 for taking in air sent from the blower 5 is formed on the upper surface 40 a of the shield case 40 of the charging device 4. The air inflow opening 43 is formed so that the opening shape is a rectangular shape extending along the longitudinal direction B of the shield case 40. Further, as shown in FIG. 4 and the like, the shield case 40 has a circumferential surface of the photosensitive drum 21 on the lower end of the side plate 40b on the upstream side in the rotation direction A of the photosensitive drum 21 and the lower end of the side plate 40c on the downstream side. There are gaps S3 and S4 with the same interval (discharge gap). The details of the blower 5 will be described later.

  The paper feeding device 30 includes a paper storage body 31 for storing a plurality of recording papers 9 having a required size and type used for image formation in a stacked state, and a recording paper stored in the paper storage body 31. And a feeding device 32 that feeds the sheets 9 toward the conveyance path one by one. When the paper feeding time comes, the recording sheets 9 are fed one by one. A plurality of paper containers 31 are provided according to the usage mode. A two-dot chain line with an arrow in FIG. 1 indicates a conveyance path in which the recording paper 9 is mainly conveyed and moved in the internal space of the housing 10. The conveyance path of the recording paper 9 includes a plurality of paper conveyance roll pairs 33a and 33b, a conveyance guide member (not shown), and the like.

  The fixing device 35 has a roll shape, a belt shape, or the like in which the surface temperature is heated and held at a required temperature by a heating unit in a housing 36 in which an introduction port and a discharge port through which the recording paper 9 passes are formed. A heating rotator 37 and a pressurizing rotator 38 such as a roll form or a belt form that are driven to rotate in contact with a required pressure so as to be substantially along the axial direction of the heating rotator 37 are provided. In the fixing device 35, a contact portion formed by contact between the heating rotator 37 and the pressing rotator 38 is configured as a fixing processing unit that performs a required fixing process (heating and heating). Fixing is performed by introducing and passing the recording paper 9 after the toner image is transferred to the contact portion.

  Image formation by the image forming apparatus 1 is performed as follows. Here, a basic image forming operation when an image is formed on one side of the recording paper 9 will be described as a representative.

  In the image forming apparatus 1, when a control device or the like (not shown) receives an image forming operation start command, in the image forming unit 20, the peripheral surface of the photosensitive drum 21 that starts rotating is charged to a predetermined polarity and potential by the charging device 4. Is done. At this time, in the charging device 4, charging voltages are respectively applied to the two corona discharge wires 41 </ b> A and 41 </ b> B, and an electric field is formed between the corona discharge wires 41 </ b> A and 41 </ b> B and the peripheral surface of the photosensitive drum 21. In this state, corona discharge is generated, whereby the peripheral surface of the photosensitive drum 21 is charged to a required potential. At this time, the charging potential of the photosensitive drum 21 is adjusted by the grid electrode 42.

  Subsequently, the charged peripheral surface of the photosensitive drum 21 is exposed based on image information from the exposure device 23 to form an electrostatic latent image having a required potential. Thereafter, when the electrostatic latent image formed on the photosensitive drum 21 passes through the developing device 24, the electrostatic latent image is developed with the toner charged to a required polarity supplied from the developing roll to be visualized as a toner image. Is done.

  Next, when the toner image formed on the photosensitive drum 21 is conveyed to the transfer position facing the transfer device 25 by the rotation of the photosensitive drum 21, the toner image passes through the conveyance path from the paper supply device 30 in accordance with this timing. Then, the image is transferred to the recording paper 9 supplied by the transfer action of the transfer device 25. The peripheral surface after the transfer of the photosensitive drum 21 is cleaned by the cleaning device 26.

  Subsequently, the recording paper 9 onto which the toner image has been transferred in the image forming unit 20 is transported so as to be introduced into the fixing device 35 after being peeled off from the photosensitive drum 21, and with the heating rotator 37 of the fixing device 35. When passing through the contact portion of the pressurizing rotator 38, the toner image is melted and fixed on the recording paper 9 by being heated under pressure. After the fixing is completed, the recording paper 9 is discharged from the fixing device 35 and is conveyed and stored in a paper discharge storage unit (not shown) provided outside the housing 10 or the like.

  In this way, a single color image composed of one color toner is formed on one side of one sheet of recording paper 9, and the basic image forming operation is completed. When there is an instruction for a plurality of image forming operations, the above-described series of operations are similarly repeated for the number of sheets.

<Configuration of blower>
Next, the blower 5 will be described.

  As shown in FIG. 1, FIG. 3, and the like, the blower 5 includes a blower 50 having a rotating fan that sends air, and a charging device 4 that is an example of a structure to be blown by taking in air sent from the blower 50. And a blower duct 51 </ b> A that guides and discharges the air.

  As the blower 50, for example, a radiant flow type blower fan is used. Further, the blower 50 is driven and controlled so as to send a required amount of air.

  As shown in FIGS. 3 to 7 and the like, the air duct 51A has an inlet 52 that takes in air sent from the blower 50, and a longitudinal direction that is long in one direction of the charging device 4 to which air taken in from the inlet 52 should be blown. An outlet 53 that is arranged in a state facing the portion B (the opening 43 in the upper surface 40a of the shield case 40) and discharges the air along a direction orthogonal to the longitudinal direction B, and the inlet 52 and the outlet 53 In the direction of flowing air in the passage space TS of the main body passage portion 54 and the main body passage portion (main body portion) 54 formed in a state where the passage space TS for flowing air between the two is bent halfway It has a shape having a first control unit 61 and a second control unit 62 which are two suppression units that are provided in different parts and suppress the flow of air.

  The inlet 52 of the air duct 51A is formed so that the entire opening shape is a slightly vertically long rectangle. A connection duct 55 for connecting the inlet 52 and the blower 50 and sending the air generated by the blower 50 to the inlet 52 is attached to the inlet 52 of the blower duct 51A (FIG. 3).

  The outlet 53 of the air duct 51 </ b> A is formed so as to have, for example, an elongated rectangular shape in which the entire opening shape extends in a state facing the opening 43 which is a portion in the longitudinal direction B of the shield case 40 of the charging device 4. As shown in FIGS. 4, 6, and the like, the outlet 53 in the first embodiment is a bottom surface (terminal) of a portion located on the outlet 53 side of the main body passage portion 54 (passage space TS of the second bending passage portion 54 </ b> C). The opening area is a little narrower than the entire area.

  As shown in FIGS. 3 to 5 and the like, the main body passage portion 54 of the air duct 51A includes an introduction passage portion 54A, a first bending passage portion 54B, and a second bending passage portion 54C.

  One end portion of the introduction passage portion 54A is opened by providing an inlet 52, and the other end portion is closed, and the whole is substantially parallel to the longitudinal direction B of the outlet 53 (same as the longitudinal direction B of the charging device 4). Thus, it is a rectangular tube-shaped passage portion having a passage space TS formed so as to extend linearly.

  The first bent passage portion 54B is bent substantially at a right angle in a substantially horizontal direction (a direction parallel to the direction indicated by the coordinate axis X) from the portion (midway) near the other end of the introduction passage portion 54A. It is a rectangular tube-shaped bent passage portion having a passage space TS formed to extend. In addition, the first bending passage portion 54B has an enlarged passage cross-sectional area with respect to the introduction passage portion 54A by expanding the width (dimension in the longitudinal direction B) while keeping the height of the passage space TS the same. The passage portion is wide in the lateral direction. A bottom surface 54e constituting the passage space TS of the first bent passage portion 54B is formed as a flat surface.

  54 C of 2nd bending channel | path parts are bent toward the downward direction (direction substantially parallel to the direction shown by the coordinate axis Y) from the downstream edge part (terminal) of the direction through which the air of the 1st bending channel | path part 54B flows. 4 is a bent passage portion having a passage space TS that is formed so as to be extended close to 4. Further, the second bent passage portion 54C is bent downward (wide in the lateral direction) with the width of the passage space TS (the dimension in the longitudinal direction B) being the same as the first bent passage portion 54B. ) It is a passage section. Furthermore, an outlet 53 having the above-described configuration is provided at the end of the passage space TS in the second bent passage portion 54C.

  Further, as shown in FIG. 3 to FIG. 5 and the like, the first suppression portion 61 in the air duct 51A blocks and crosses a part of the passage space TS in the first bending passage portion 54B and in the transverse direction. It is provided as a suppressing portion having a structure in which a gap 64 extending linearly exists.

  Specifically, the first restraining portion 61 is depressed so that a part forming the outer shape of the first bent passage portion 54B is intruded into the passage space TS and crosses a part of the passage space TS. In addition, the gap 64 having the required distance d exists between the passage space TS and the bottom surface 54e of the passage space TS. A portion 65 that cuts off a part of the passage space TS is a blocking portion that constitutes the first suppressing portion 61.

  In the first embodiment, the blocking portion 65 in the first suppressing portion 61 is arranged so that the direction crossing the passage space TS is parallel to the longitudinal direction B of the outlet 53. Further, the blocking portion 65 has a lower end of the inner wall surface portion 65a on the upstream side in the direction of flowing air in the direction of flowing air of the first bent passage portion 54B from the end portion 52a near the outlet 53 of the opening portion of the inlet 52. It is arranged on the downstream side so as to exist at a position shifted by a required distance N (FIG. 7). Both the inner wall surface portions 65a and 65b on the upstream side and the downstream side of the blocking portion 65 are configured as flat surfaces.

  On the other hand, the gap 64 in the first suppressing portion 61 exists between the lower end inner wall surface portion 65c of the blocking portion 65 and the bottom surface 54e in the passage space TS of the first bent passage portion 54B. It exists in a state extending in a direction crossing a part. The gap 64 in the first embodiment is arranged so as to be in a state parallel to the longitudinal direction B of the outlet 53, similarly to the blocking portion 65. The gap 64 is set to have the same width (length in the longitudinal direction B) as the width W (FIG. 5) of the passage space TS of the first bending passage portion 54B. Further, the gap 64 is set so that the path length M thereof has a predetermined dimension by the lower end inner wall surface portion 65 c of the blocking portion 65.

  The shielding member 65 in the first suppression unit 61 is obtained by integrally molding the same material as that of the air duct 51, but may be obtained by being formed of a material different from that of the air duct 51. Further, the shielding portion 65 has an arrangement position (the above distance N), an interval d of the gap 64, a path length M, and a width W, and the wind speed of the air flowing into the first bending path section 54B from the introduction path section 54A. Is selected and set from the viewpoint of equalizing as much as possible. These values are set in consideration of the size (capacity) of the air duct 51A and the flow rate (air volume) per unit time of the air that should flow through the air duct 51A or the charging device 4. In FIG. 4 and the like, reference numeral TS1 indicates a passage space that exists on the upstream side of the passage space TS of the main body passage portion 64 in the direction in which air flows than the first suppression portion 61, and reference numeral TS2 similarly indicates the first suppression portion 61. 2 also shows a passage space existing on the downstream side in the air flow direction.

  Furthermore, the 2nd suppression part 62 in 51 A of ventilation ducts is as a suppression part of the structure which made the exit 53 closed with the air permeable member 70 which has the some ventilation part 71, as FIG.4, FIG.6 etc. show. Is provided.

  As shown in FIGS. 4, 6, and the like, each of the plurality of ventilation portions 71 is a through-hole extending so that each opening shape is substantially circular and penetrates linearly. Further, the plurality of ventilation portions 71 are arranged at equal intervals along the longitudinal direction B of the opening shape of the outlet 53, for example, and a plurality of examples in the short direction C orthogonal to the longitudinal direction B at the same interval as the above-described equal intervals. They are arranged to form (for example, 5 columns). Thus, the plurality of ventilation portions (holes) 71 are formed so as to be scattered almost uniformly throughout the opening shape of the outlet 53. For this reason, the air-permeable member 70 in Embodiment 1 is a perforated plate formed so that a plurality of ventilation portions (holes) 71 are dotted on a plate-like member.

  The breathable member 70 may be obtained by integrally molding the same material as the air duct 51A, or may be formed of a material different from the air duct 51A. The opening shape, opening size, hole length, and hole existence density of the ventilation portion (hole) 71 are selected and set from the viewpoint of making the air velocity of the air flowing out from the second bending passage portion 54C through the outlet 53 as uniform as possible. In addition, the size (capacity) of the air duct 51A and the flow rate per unit time of the air to be passed through the air duct 51A or the charging device 4 are set.

Here, in the air duct 51A in the first embodiment, since the opening shape of the inlet 52 is a slightly vertically long rectangle and the opening shape of the outlet 53 is a horizontally long rectangle, the opening 52 and the outlet 53 are different. The relationship is formed by a shape. For this reason, the air duct 51A has a portion in which at least one of the cross-sectional shape (dimension) of the passage space TS and the direction in which the air flows is changed in the passage portion 54 connecting the inlet 52 and the outlet 53. Will do. In this specification and the like, even when the inlet 52 and the outlet 53 have the same type of shape (for example, rectangles), when the opening areas are different from each other, they are formed with different opening shapes. Included in the relationship.
In the air duct (51A) having such a portion that changes in the middle, generally, the air flow is disturbed such as separation or vortex in the portion where the cross-sectional shape or the direction in which the air flows is changed. It is known that even if air having a uniform wind speed is taken in, the air coming out from the outlet 53 tends to have non-uniform wind speed, particularly in the longitudinal direction B of the outlet 53.

  In order to solve such a problem, the present applicant has made a proposal regarding a blower device using a blower pipe provided with a plurality of suppression units as shown in Patent Document 1 described above. Also in the air duct 51A in the first embodiment, since the two suppressing portions 61 and 62 are provided, the longitudinal direction B of the air discharged from the outlet 53 and the short direction perpendicular to the longitudinal direction B as described above. Unevenness of the wind speed at C is reduced.

  However, as a result of further research after that, in the air blowing device using the air duct proposed above, air containing discharge products such as ozone and nitrogen oxides generated during corona discharge in the charging device 4 is discharged in the charging device 4. The shield case 40 may flow out to the outer space of the shield case 40 through a gap S3 between the side plate 40b on the upstream side in the rotational direction A of the photosensitive drum 21 and the peripheral surface (surface) of the photosensitive drum 21. It has been newly found that the discharge product may stay in the outer space and induce image defects. Examples of image defects include defects such as white spots in the image due to adhesion of discharge products.

As a countermeasure against such a phenomenon that the air containing the discharge product flows out, for example, the air containing the discharge product around the upstream (the empty space) in the rotation direction A of the photosensitive drum 21 in the charging device 4. It is conceivable to install an intake fan or an intake duct for suctioning and eliminating.
When this measure is adopted, the discharge product flowing out can be recovered, but the intake action of the intake fan or intake duct installed in the measure extends to the gap (S3), so the influence is exerted on the intake duct. The flow of the air discharged from the outlet 53 of 51A also extends, and as a result, the effect of reducing the unevenness of the wind speed in the longitudinal direction B and the short direction C of the air discharged from the outlet 53 is difficult to obtain as desired. There is a tendency. In addition, there is a disadvantage that a new intake fan or intake duct must be added.

  Therefore, in the air duct 51A according to the first embodiment, as shown in FIGS. 4 to 7 and the like, the gap 64 of the first control unit 61 among the inner wall surfaces constituting the passage space TS of the first bending passage portion The bottom surface portion 54e facing each other branches from a portion extending along the direction crossing the first control unit 61, and is close to the surface of the photosensitive drum 21 outside the side plate 40b of the shield case 40 in the charging device 4. A branch passage portion 57A having a diversion passage space TS3 extending to a position where it is located is provided.

The branch passage portion 57A is elongated along the direction crossing the first control portion 61 to the bottom portion 54f facing the gap 64 of the first control portion 61 at the bottom surface 54e constituting the passage space TS of the first bending passage portion. A rectangular plate provided with a branch opening 57a of the branch passage space TS3 having a rectangular shape, and having the branch passage space TS3 whose section is the opening shape of the branch opening 58 and continuing to a position close to the surface of the photosensitive drum 21. It is comprised by the cylindrical body.
A terminal opening 57b serving as a terminal opening is provided at the terminal position of the branch passage portion 57A that is close to the surface of the photosensitive drum 21. This end opening 57b is formed in the same opening shape (elongated rectangle) as the branch opening 57a. Further, both the branch opening 57 a and the terminal opening 57 b are formed so as to extend in a direction parallel to the longitudinal direction B of the outlet 53. The diversion passage space TS3 in the first embodiment is a thin flat space.
Such a branch passage portion 57A is integrally formed using the same material as the air duct 51A, or is formed as a separate body using a material different from the air duct 51A.

  Further, as shown in FIG. 7 and the like, the branch passage portion 57A has a branch start position (a position of the branch opening 57a) in the branch passage space TS3, for example, a path length of the gap 64 of the first control portion 61. It arrange | positions so that it may exist in the approximate center position in M. Further, the branch passage space TS3 in the branch passage portion 57A has a cross-sectional space in which the passage height h is set to a required value and the passage width is set to the same dimension as the width W of the first bent passage portion 54B. It is configured as. Further, the passage length of the branch passage space TS3 is the length from the branch opening 57a to the terminal opening 57b, and is actually determined by the position of the terminal opening 57b.

  Further, in the branch passage portion 57A, as shown in an enlarged view in FIG. 8, the distance r between the end opening 57b and the surface of the photosensitive drum 21 is set to a required dimension. The distance r is desirably a minimum dimension that can avoid contact with the surface of the photosensitive drum 21, for example. The distance r is an upstream distance r1 at the upstream end of the opening 57b in the rotational direction A of the photosensitive drum 21 and a downstream distance at the downstream end of the distal opening 57b in the rotational direction A of the photosensitive drum 21. Although it can be obtained as an average value with the distance r2 on the side, strictly speaking, the distance r1 on the upstream side is important. Incidentally, the distances r1 and r2 are the same values when compared with the gaps S3 and S4 between the lower ends of the side plates 40b and 40c of the shield case 40 of the charging device 4 and the peripheral surface of the photosensitive drum 21. Or it is set to a slightly narrow value.

  Furthermore, since the branch passage portion 57A is substantially parallel to the branch passage space TS extending linearly from the branch opening 57a to the end opening 57b, the entire passage portion (including the end opening 57b) is charged. The shield case 40 in the apparatus 4 is provided in a state of being separated from the upstream side plate 40b by a required distance k. In this case, a space exists between the branch passage portion 57A and the side plate 40b on the upstream side of the shield case 40.

<Operation of blower>
Hereinafter, the operation of the blower 5 (mainly due to the blower duct 51A) will be described.

  In the blower device 5, when a drive setting time such as an image forming operation arrives, the blower 50 is first rotationally driven to send out a required amount of air. The air (E) sent from the started blower 50 is taken in from the inlet 52 of the blower duct 51A through the connection duct 55 and then sent so as to flow into the passage space TS of the introduction passage portion 54A (FIG. 5). ).

  Subsequently, the air (E) taken into the blower duct 51A is sent to flow into the passage space TS of the first bending passage portion 54B through the passage space TS of the introduction passage portion 54A, as shown in FIGS. (See arrows E1a, E1b, etc. in FIG. 5). The air (E1) sent to the first bending passage portion 54B passes through the gap 64 of the first suppressing portion 61 and advances in a state in which its traveling direction (air flowing direction) is changed to a substantially perpendicular direction. .

  At this time, the air (E2) when passing through the gap 64 of the first suppression portion 61A has a relatively narrow gap 64 of the first suppression portion 61 whose flow area is relatively smaller than the cross-sectional area of the passage space TS of the introduction passage portion 54A. Is suppressed (becomes in a state where the pressure has increased), and tries to flow out from the gap 64 in a uniform state. In addition, the air (E2) when flowing into the passage space TS of the first bent passage portion 54B is aligned in a direction substantially perpendicular to the longitudinal direction B of the outlet 53 when flowing out from the gap 64 of the first suppressing portion 61. .

  Subsequently, the air (E2) that has flowed into the passage space TS of the second bent passage portion 54C is secondly passed through the gap 64 of the first suppressing portion 61 as shown in FIG. It flows so as to travel substantially straight in the passage space TS of the bent passage portion 54C. The air (E2a) that has flown so as to travel substantially straightly bends and proceeds to the lower side where there is an outlet 53 that is partly traveling straight. On the other hand, a lot of the remaining air (E2b) travels so as to rise after colliding with the rear inner wall surface 58 in the downstream passage space TS2, and moves so as to circulate in the passage space TS2. This circulating air (E2b) moves again so as to advance toward the outlet 53 below the passage space TS2.

  At this time, the air (E2) flowing into the passage space TS of the second bent passage portion 54C flows into the passage space TS2 on the downstream side having a larger volume than the space of the gap 64 of the first suppressing portion 61A. Since it progresses so that it may diffuse in space TS2 and it circulates as mentioned above (E2b), it will be in the state where it swirled in passage space TS2, and it will stay temporarily, and the nonuniformity of the wind speed is reduced. .

  Finally, the air (E2) that flows into the downstream passage space TS2, circulates, and stays temporarily is provided at the outlet 53, which is the end of the second bending passage portion 54C, as shown by an arrow E3 in FIG. By passing through a plurality of ventilation parts (holes) 71 in the air-permeable member 70 of the second suppressing part 62, the outlet 53 is blown out in a state in which the traveling direction is changed (direction and length of the arrow E3, etc.) See).

  At this time, the air (E3) blown out from the outlet 53 is a plurality of ventilation portions 71 in the region 70b of the breathable member 70 that is relatively narrower than the passage space TS of the second bending passage portion 54C and the opening area of the outlet 53. As the flow passes, the flow is suppressed (the pressure is also increased at this time) and sent out.

  As described above, the air (E3) discharged from the outlet 53 of the air duct 51A is discharged in a state in which the wind speed is substantially uniform in the longitudinal direction B and the lateral direction C of the opening shape (elongated rectangle) of the outlet 53. .

The air (E3) discharged from the outlet 53 of the blower duct 51A in the blower device 5 passes through the opening 43 in the upper surface 40a of the shield case 40 of the charging device 4, as shown in FIG. Corona discharge wires 41A and 41B in the spaces (S1 and S2) separated by the partition wall 40d in the inner space S of the shield case 40 and the lower portion of the shield case 40 Sprayed onto the grid electrode 42 in the opening.
Since the air blown to the corona discharge wires 41A and 41B and the grid electrode 42 is discharged at a wind speed substantially equal in the longitudinal direction B of the outlet 53 of the air duct 51, the air (E3) is discharged as described above. The discharge wires 41 </ b> A and 41 </ b> B and the grid electrode 42 are also sprayed in a substantially equal state in the longitudinal direction B.

  As a result, unnecessary substances such as paper dust, toner external additives, and discharge products that are to adhere to the two corona discharge wires 41A and 41B and the grid electrode 42 in the charging device 4 are made more uniform in air. Can be kept away by spraying.

  As a result, in the charging device 4, it is possible to prevent a deterioration phenomenon such as uneven discharge performance (charging performance) from occurring due to sparsely attached unnecessary materials on the corona discharge wires 41 </ b> A and 41 </ b> B and the grid electrode 42. The peripheral surface of the photosensitive drum 21 can be charged more uniformly (uniformly with respect to the rotation axis direction).

  In addition, in the air duct 51 </ b> A in the air blower 5, a part (E <b> 4) of the air E <b> 2 that passes through the gap 64 of the first suppressing portion 61 is diverted from the branch opening 57 a that exists in the gap 64. The flow is divided into the flow dividing space TS3 and discharged from the end opening 57b of the flow dividing space TS3.

  Most of the air (E4a) discharged from the end opening 57b of the branch passage portion 57A is generated in the surface airflow E5 generated as the peripheral surface of the photosensitive drum 21 rotates in the direction indicated by the arrow A. It is attracted and carried toward the gap S 3 between the lower end of the upstream side plate 40 b in the shield case 40 of the charging device 4 and the peripheral surface of the photosensitive drum 21.

  At this time, in the charging device 4, a part (E7c) of the air (E3) blown from the outlet 53 of the blower duct 51A through the air inflow opening 43 to the internal space S of the shield case 40 is used as the shield case 40. May move downward along the upstream side plate 40b so as to flow out of the gap S3 at the lower end of the side plate 40b. In addition, the air (E7c) about to flow out from the gap S3 generally includes discharge products such as ozone generated in the shield case 40 during corona discharge of the charging device 4.

  However, the air (E7c) about to flow out from the gap S3 is discharged from the end opening 57b of the branch passage portion 57A and flows like an air curtain so as to approach the gap S3 (E4a) (including the surface airflow E5). The path is blocked, and it becomes difficult to flow out of the gap S3. As a result, in the charging device 4, the air (E7c) containing the discharge product is suppressed from flowing out to the outer space of the upstream side plate 40b in the shield case 40 through the gap S3.

  As a result, the toner image formed by the image forming unit 20 provided with the charging device 4 and the image finally formed on the recording paper 9 are defective in image quality due to charging failure such as uneven charging (density unevenness, etc.). It is possible to obtain a good image quality with reduced occurrence of image quality. Further, in the image forming unit 20, the discharge product generated by the charging device 4 is suppressed from flowing out and staying in the outer space of the upstream side plate 40 b in the shield case 40. The possibility that the above-described image defect due to the retention will occur is also reduced. For this reason, in this image forming apparatus 1, it is not necessary to install equipment such as an intake fan and a suction duct for sucking discharge products flowing out to the outer space of the upstream side plate 40b in the shield case 40.

Incidentally, in the blower 5, a part (E4) of the air (E) taken from the inlet 52 in the blower duct 51A is discharged and consumed through the branch passage space TS3 of the branch passage portion 57A.
However, the amount of air (E4) that flows into the branch passage portion 57A and is discharged is relatively small compared to the total amount of air (E) that is taken in, and the gap 64 of the first suppression portion 61 is reduced. The flow rate and momentum of the passing air (E2) are hardly adversely affected, and the air does not act to suck the air in the shield case 40 outward from the gap S3. The air (E3) released from the air can be maintained almost as it is without hindering the above-described effect of suppressing the uneven wind speed.
A part (E4b) of the air discharged from the end opening 57b of the branch passage portion 57A is discharged to the upstream side in the rotation direction A of the photosensitive drum 21, as illustrated in FIG. However, the amount of air (E4b) is very small compared to the total amount of air (mainly air E4a) discharged from the branch passage portion 57A, and most of the air (E4b) is on the peripheral surface of the photosensitive drum 21. Carried by surface airflow (E5).

In the image forming apparatus 1, for example, since the developer (toner) may leak to the outside of the developing device 24 and float during the developing process of the developing device 24, a suction mechanism for sucking the floating toner. May be installed around the developing device 24.
In this case, the suction (intake) action by the suction mechanism may reach around the charging device 4 in the vicinity of the developing device 24. For this reason, in the charging device 4, the air (E3) blown from the blower duct 51 </ b> A of the blower 5 to the internal space S of the shield case 40 is, for example, corona discharge wires as illustrated as E <b> 7 a and E <b> 7 b in FIG. 8. After flowing so as to pass through 41A and 41B, it flows so as to be sucked toward the gap S4 existing between the lower end of the downstream side plate 40c in the shield case 40 and the peripheral surface of the photosensitive drum 21. . Further, the air (E7a, E7b) finally passes through the gap S4 and becomes air (E8) flowing out to the outer space of the shield case 40, and is sucked by the suction mechanism.
Thereby, the discharge product contained in the air (E7a, E7b or E8) is collected by the suction mechanism. In addition, due to the suction action of such an intake mechanism, the air (E3) blown into the inner space S of the shield case 40 moves toward the gap S4 and flows like the air (E7a, E7b). There is an effect that the air E7c containing the discharge product is less likely to flow out to the outside through the gap S3.

<Test>
FIG. 10 shows the results of a test in which the performance characteristics of the blower 5 (inhibition effect on ozone outflow from the lower end gap on the upstream side of the charging device) were examined.

In the test, an air duct 51A having the following conditions is used, and air with an average air volume of about 0.33 m ³ / min is introduced from the air blower 50 through the inlet 52 of the air duct 51A, and the charging device 4 through the outlet 53. The lower end of the side plate 40b on the upstream side of the shield case 40 is sprayed onto the shield case 40 having the following conditions and when a predetermined number of ozone flows in from the air inflow opening 43 of the shield case 40 in the charging device 4. The number of ozone flowing out from the gap (S3) between the photosensitive drum 21 and the peripheral surface of the photosensitive drum 21 was measured.

  For ozone, a test apparatus configured such that only a part of the photosensitive drum 21 and the charging apparatus 4 in the image forming apparatus 20 used in the first embodiment operates is prepared, and the charging apparatus 4 in the test apparatus is prepared. After collecting ozone generated from the ozone, the ozone was allowed to flow into the shield case 40 of the charging device 4 at the test stage. The number of ozone outflows was measured using an ozone concentration measuring device (output value ppm).

The entire shape of the air duct 51A is as shown in FIGS. 3 to 6, the inlet 52 is an opening shape of a substantially square (a slightly vertically long rectangle) of 22 mm × 23 mm, and the outlet 53 is 17 The one having an elongated rectangular opening shape of 5 mm × 350 mm was used. The total volume of all passage spaces TS of the air duct 51A is about 600 cm ³ .
Further, the first suppressing portion 61A in the air duct 51A has a distance d of 1.5 mm and a path in a portion where the deviation amount N from the one end portion 52a of the inlet 52 is 6 mm in the passage space TS of the first bent passage portion 54A. A gap 64 having a length M of 8 mm and a width W of 345 mm is configured to be present in contact with the bottom surface 54e of the first bending passage portion 54B.
Further, the second suppressing portion 62 in the air duct 51A is a porous hole provided with vent holes 71 having a hole diameter of 1 mm and a length of 3 mm under the condition that the density is 0.42 / mm ² (≈42 / cm ² ). It was comprised using the sex member 70.

  Further, as shown in Nos. 4 to 9 in FIG. 10, the branch passage portion 57A in the air duct 51A has a branch start position of the branch passage space TS3, a side surface portion (side plate 40b) on the upstream side of the charging device 4. The distance k is set, and the distance r between the end opening 57b and the surface of the photosensitive drum 21 is set. The branch start position is arranged such that the branch opening 57a exists in the bottom surface portion (surface portion) 54f facing the substantially central position of the path length M of the gap 64 in the first suppressing portion 61. In the branch passage portion 57A, the height h of the branch passage space TS3 is 1.5 mm, and the path length from the branch opening 57a to the end opening 57b of the branch passage space TS3 is 40 mm except for the above configuration. Further, as shown in FIG. 8, the terminal opening 57b of the branch passage space TS3 in the branch passage portion 57A is configured such that the upstream distance r1 and the downstream distance r2 have substantially the same value.

As the shielding case 40 of the charging device 4, a case in which the dimensions of vertical (direction of coordinate axis Y) × horizontal (direction of coordinate axis X) × depth (direction of coordinate axis Z) is set to about 35 mm × 40 mm × 380 mm is used. . Also, the shield case 40 rotates the photosensitive drum 21 as the lower side plate of the upstream side plate 40b and the downstream side plate 40c approaches the surface of the photosensitive drum 21 with respect to the top plate 40a. The side plate was inclined so as to be shifted downstream in the direction A. Further, the shield case 40 was set such that the clearance S3 at the lower end of the upstream side plate 40b was 1 mm, and the clearance S4 at the lower end of the downstream side plate 40c was 1 mm.
Further, a cylindrical drum having a diameter of 840 mm was used as the photosensitive drum 21 and was rotated in the direction of arrow A at a speed of 500 mm / second.

From the results shown in No. 4 to No. 9 in FIG. 10, when the branch start position of the branch passage space TS3 in the branch passage portion 57A (arrangement existing in the surface portion 54f facing the gap 64) is common, As the distance k between the branch passage portion 57A and the side surface portion of the charging device 4 increases, the number of ozone outflows tends to decrease, and the surface of the photosensitive drum 21 in the branch passage portion 57A does not depend on the size of the distance k. It can be seen that the smaller the distance r, the smaller the number of ozone outflows. In particular, in the case of Test Nos. 7 and 8, the best result was obtained that the number of ozone outflows was zero.
Incidentally, in this test, the wind speed of the air discharged from the outlet 53 of the air duct 51A provided with each of the branch passage portions 57A was also measured and examined. As a result, in each air duct 51A, the unevenness of the wind speed in the longitudinal direction of the outlet 53 and the unevenness of the wind speed in the short direction C are suppressed, and the charging device is provided regardless of the provision of each branch passage portion 57A. It was confirmed that blowing air with reduced wind speed unevenness toward the air inflow opening 43 in the shield case 40 of No. 4 was maintained.

[Embodiment 2]
FIG. 11 shows an outline of the main part (mainly the air duct 51B) of the air blower 5 according to the second embodiment.

  The blower duct 51B in the blower device 5 according to the second embodiment is the same as that of the first embodiment except that the branch passage portion 57B is slightly changed in place of the branch passage portion 57A in the first embodiment. It consists of the same structure as the ventilation duct 51A which concerns.

  The branch passage portion 57B in the air duct 51B has a branch opening 57a corresponding to the branch start position of the branch passage space TS3, and the first control portion 61 in the bottom surface 54e constituting the passage space TS of the first bent passage portion 54B. It is arrange | positioned so that it may exist in the bottom face part 57g which is a surface part after passing the clearance gap 64 of this. The bottom surface portion 57g is a portion of the bottom surface 54e that extends from the opening end 64b on the downstream side in the direction of flowing the air in the gap 64 of the first control unit 61 to the end of the plane portion of the passage space TS (TS1). The branch opening 57a of the branch passage portion 57B in the second embodiment is set so that the separation distance j from the downstream opening end 64b in the gap 64 of the first control unit 61 becomes a required value.

  Further, the branch passage portion 57B is in a state of being substantially parallel to the upstream side plate 40b in the shield case 40 of the charging device 4 in the same manner as the branch passage portion 57A in the first embodiment in relation to the arrangement position of the branch opening 57a. In this case, the distance k between the shield case 40 and the upstream side plate 40b is smaller than the distance k of the branch passage portion 57A in the first embodiment.

  And the air blower 5 using this air duct 51B operate | moves substantially similarly to the case of the air blower 5 which concerns on Embodiment 1. FIG.

  Moreover, in this ventilation duct 51B, as illustrated in FIG. 12, a part (E4) of the air E2 passing through the gap 64 of the first suppression unit 61 passes through the gap 64 to the bottom surface portion 57g. From the branch opening 57a existing on the way, it flows into the diversion passage space TS3 of the branch passage portion 57B, and is discharged from the end opening 57b of the diversion passage space TS3.

  Most of the air (E4a) discharged from the end opening 57b of the branch passage portion 57B is attracted by the surface airflow E5 generated along with the movement of the peripheral surface of the photosensitive drum 21, and the shielding of the charging device 4 The case 40 is conveyed toward the gap S3 between the lower end of the upstream side plate 40b and the peripheral surface of the photosensitive drum 21.

At this time, in the charging device 4, as described in the first embodiment, a part (E7c) of the air (E3) blown into the internal space S of the shield case 40 of the air duct 51B is discharged by ozone or the like. In a state including the product, the shield case 40 may move so as to flow out from the gap S3 at the lower end of the upstream side plate 40b.
However, also in the air duct 51B, the air (E7c) that is about to flow out from the gap S3 between the shield case 40 and the photosensitive drum 21 is discharged from the end opening 57b of the branch passage portion 57B, and the gap S3. The air (E4a) (including the surface airflow E5) that flows like an air curtain so as to approach the air path is blocked, and it becomes difficult to flow out of the gap S3.
As a result, also in this charging device 4, the air (E7c) containing the discharge product is suppressed from flowing out to the outer space of the upstream side plate 40b in the shield case 40 through the gap S3.

<Test>
Further, the performance characteristics of the blower device 5 provided with the blower duct 51B were also examined in the same manner as the test in the first embodiment. The results of this test are also shown in FIG.

In this test, an air duct having the same conditions as the air duct 51A used in the test in Embodiment 1 was used except that the branch passage portion 57B configured as follows was applied as the air duct 51B. .
As the branch passage portion 57B in the air duct 51B, as shown in Nos. 1 to 3 in FIG. 10, the branch start position of the branch passage space TS3, the side surface portion (side plate 40b) on the upstream side of the charging device 4, and The distance k and the distance r between the end opening 57b and the surface of the photosensitive drum 21 are set. The branch start position was arranged such that the branch opening 57a exists in the bottom surface portion (surface portion) 54g where the separation distance j from the downstream opening end 64b of the gap 64 in the first suppressing portion 61 is 4 mm. The branch passage portion 57B has the same configuration as the branch passage portion 57A in the first embodiment except for the above configuration.

From the results shown in Nos. 1 to 3 in FIG. 10, the branch start position of the branch passage space TS3 in the branch passage portion 57B (the arrangement existing in the surface portion 54g after passing through the gap 64) is common. In this case, it can be seen that the number of ozone outflows tends to decrease as the distance r between the branch passage portion 57B and the surface of the photosensitive drum 21 decreases. Incidentally, also in this test, when the wind speed of the air discharged from the outlet 53 of the air duct 51B provided with each of the branch passage portions 57B was measured and examined, in each air duct 51B, the outlet 53 Unevenness of the wind speed in the longitudinal direction and the unevenness of the wind speed in the short direction C are suppressed, and the air inflow opening 43 in the shield case 40 of the charging device 4 is provided regardless of the provision of each branch passage portion 57B. It was confirmed that blowing air with reduced wind speed unevenness was maintained.
On the other hand, when the distance k to the side surface portion of the charging device 4 is reduced as in the branch passage portion 57B, the distance k is increased as in the branch passage portion 57A in the first embodiment (see FIG. 10). It can be seen that the total number of ozone outflows tends to increase as compared with No. 4-9). In other words, the branch passage portion 57 tends to decrease the number of outflows of ozone as the distance k to the charging device 4 is increased as the distance k as in the branch passage portion 57A in the first embodiment. Turned out to be.

[Other embodiments]
As the air duct 51 used in the air blower 5, it is also possible to apply an air duct provided with a branch passage portion 57C or the like in which the branch passage portion 57 is further changed partially.

For example, as illustrated in FIG. 13, a branch passage portion 57 </ b> C in which a passage member 571 that is at least a part of the diversion passage space TS <b> 3 is configured and provided by a side plate 40 b on the upstream side of the shield case 40 of the charging device 4. You may apply the air duct 51C provided with. The branch passage portion 57C illustrated in FIG. 13 is configured by using the side plate 40b on the upstream side of the portion (571) facing the side plate 40b on the upstream side of the shield case 40 in the shunt passage space TS3. It is what. Further, the branch passage portion 57C is set in the bottom surface portion 57g in the same manner as the branch passage portion 57B in the second embodiment, for example, with respect to the installation position of the branch opening 57a of the branch passage space TS3. As in the case of the branch passage portion 57A in the first embodiment, it may be set in the bottom surface portion 5f facing the gap 64.
When such a branch passage portion 57C is provided, the same material as that of the main body of the branch passage portion 57C is used for a portion remaining between the passage member 571 and the branch opening 57a which are at least a part of the branch passage space TS3. Alternatively, the air duct 51C may be formed using the same material as the air duct 51C.

  Further, as illustrated in FIG. 14, at least the end opening 57 b in the diversion passage space TS 3 is present at the end of the bent portion 57 m bent toward the side plate 40 b on the upstream side of the shield case 40 of the charging device 4. You may apply the ventilation duct (51) provided with the branch channel | path part 57D provided so that it may do. In the branch passage portion 57D illustrated in FIG. 14, the bent portion 57m is formed at the end portion close to the surface of the photosensitive drum 21. Further, the end opening 57b formed at the end of the bent portion 57m is set so that the distance r to the surface of the photosensitive drum 21 is smaller than the distance r1 on the upstream side than the distance r2 on the downstream side. The The bent portion 57m can be applied not only to the branch passage portion 57A in the first embodiment, but also to the branch passage portion 57B in the second embodiment and the branch passage portion 57C in the modified example.

  In the case of the air duct provided with the branch passage portion 57D, the air (E4a) flowing and flowing into the branch passage space TS3 of the branch passage portion 57D has a traveling direction when passing through the bent portion 57m. 40 is changed to positively approach the gap S3 at the end of the side plate 40b on the upstream side of 40 and discharged. As a result, the air (E4a) efficiently flows and moves in the gap S3 at the end of the side plate 40b on the upstream side of the shield case 40, so that the discharge product is about to flow out of the gap S3 into the outer space. The air (E7c) containing can be reliably suppressed.

  Moreover, the air duct 51 used for the air blower 5 is not limited to the case where the second suppressing portion 62 provided at the outlet 53 is configured by the air-permeable member 70 exemplified in the first and second embodiments. It may be configured using a breathable member 70 typified by a porous member such as a non-woven fabric (one in which the plurality of ventilation portions 71 are irregularly shaped through gaps) applied to the above.

  Further, the charging device 4 to which the blower device 5 is applied may be a charging device of a type in which the grid electrode 24 is not installed, that is, a so-called corotron type charging device. Further, the charging device 4 may be one that uses one or three or more corona discharge wires 41. The corona discharger to which the blower 5 is applied may be a corona discharger for discharging the photosensitive drum 21 or the like, or a corona discharger for charging or discharging a rotating charged object other than the photosensitive drum. The rotating object to be discharged that receives corona discharge by the corona discharger is not limited to a drum type, and may be a belt type. Further, the rotating object to be discharged when corona discharge is performed by the corona discharger is not limited to a curved surface having a constant curvature, but may be a flat surface through the discharge opening.

  In addition, the configuration of the image forming method and the like is not particularly limited as long as the image forming apparatus 1 is equipped with a long target structure to which the blower 5 needs to be applied. For example, in the first embodiment, the image forming apparatus 1 is exemplified to form a single color image using one image forming unit 20, but the image forming apparatus forms an image of a different color. The image forming apparatus may form a multicolor image using a plurality of image forming units 20.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 4 ... Charging apparatus (corona discharger)
5 ... Blower 21 ... Photosensitive drum (an example of a rotating object to be discharged)
40 ... Shield case (an example of a cover member)
40b: Side plate on the upstream side in the rotational direction (an example of a side surface portion on the upstream side in the rotational direction)
43 ... Air inflow opening 44 ... Discharge opening 50 ... Blower 51 ... Blower duct (Blower tube)
52 ... Inlet 53 ... Outlet 54 ... Main body passage portion 54A ... Introduction passage portion 54B ... First bending passage portion 54C ... Second bending passage portion 54e ... Bottom surface (an example of an inner wall surface constituting the passage space of the first bending passage portion)
54f: Bottom portion facing the gap (an example of a surface portion facing the gap)
54g: Bottom portion after passing through the gap (an example of the surface portion after passing through the gap)
57 ... branch passage part 57b ... terminal opening (terminal opening part)
57m ... bent portion 61 ... first suppressing portion 62 ... second suppressing portion 64 ... gap 70 ... breathable member 71 ... vent portion A ... rotating direction of photosensitive drum (rotating direction of rotating object to be discharged)
B ... Longitudinal direction (an example of one direction)
E ... Air (flowing air)
TS ... passage space r1 ... distance (distance between the lower end of the side surface portion on the upstream side in the rotation direction and the surface of the rotating object to be discharged)
r2 Distance (distance between the lower end of the side surface downstream in the rotation direction and the surface of the rotating object to be discharged)
k ... distance

Claims (7)

From an introduction passage portion having a passage space provided at one end with an inlet for taking in air, a first bending passage portion having a passage space that bends in the lateral direction from the middle of the introduction passage portion, and an end of the first bending passage portion An outlet having an opening shape that extends in a state facing a long air inlet opening in one direction in a cover member of a corona discharger that is bent downward and is blown with air taken in from the inlet at the end bent downward A main body passage portion constituted by a second bending passage portion having a passage space provided with;
A first suppression unit that blocks and crosses a part of the passage space of the first bending passage unit and suppresses the flow of air as a structure in which a gap exists at the lower end;
A second suppression unit that suppresses the flow of air as a structure in which the outlet is closed with a breathable member interspersed with a plurality of ventilation units;
Of the inner wall surface constituting the passage space of the first bending passage portion, the surface portion facing the gap of the first control portion or the surface portion after passing through the gap, in the direction crossing the first control portion. Branching from a portion extending along the corona discharger, the outer surface of the corona discharger that is on the upstream side in the rotation direction of the discharge target rotation subject to corona discharge by the corona discharger, the discharge target rotation object A branch passage portion having a branch passage space extending to a position approaching the surface of
Blower tube with.   The branch passage portion has a side surface in which at least a terminal opening facing the surface of the discharge object rotating object in the shunt passage space is upstream in the rotation direction of the discharge object rotating object in the covering member of the corona discharger. The blower pipe according to claim 1, wherein the blower pipe is provided so as to exist at a position distant from the portion.   The branch passage portion is configured such that at least a part of the diversion passage space is formed by a side surface portion of the covering member of the corona discharger that is located upstream in the rotation direction of the rotating object to be discharged. The blower tube according to 1.   The branch passage portion has a side surface in which at least a terminal opening facing the surface of the discharge object rotating object in the shunt passage space is upstream in the rotation direction of the discharge object rotating object in the covering member of the corona discharger. The blower pipe according to any one of claims 1 to 3, wherein the blower pipe is provided so as to be present at an end of a bent portion bent toward the side approaching the portion. When applying the rotating object to be discharged as a rotating object to be discharged, the surface part when passing through the corona discharger is a curved surface having at least a certain curvature,
The branch passage portion has a distance between a lower end of a side surface portion on the upstream side in the rotation direction of the discharge object rotating object and a surface of the discharge object rotation object in the portion constituting the diversion passage space. The lower part of the side part which becomes the rotation direction downstream of the rotation object of the discharge object rotation object among the parts which constitute space is provided so that it may become a value shorter than or the same value as the distance of the surface of the discharge object rotation object. The blower tube according to any one of 1 to 4.   The air blower provided with the air blower which sends air, and the air blow pipe of any one of Claim 1 thru | or 5 which takes in the air sent from the said air blower. A corona discharger having a cover member provided with an air inflow opening having a long shape in one direction to which air should be blown, and a discharge opening along the longitudinal direction of the cover member of the corona discharger so as to pass through A rotating object to be rotated that receives corona discharge by the corona discharger, and a blower that blows air to an air inflow opening in a cover member of the corona discharger,
An image forming apparatus in which the blower is configured by the blower according to claim 6.

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