JP6003761B2 - Blower tube, blower, and image forming apparatus - Google Patents

Description

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

  In an image forming apparatus that forms an image composed of a developer on a recording sheet, for example, a process of charging or discharging a latent image holder such as a photoconductor, a process of transferring an unfixed image to a recording sheet, and the like Use a corona discharger that performs corona discharge.

  In the corona discharger, a blower that blows air toward the component parts in order to prevent unnecessary substances such as paper dust and discharge products from adhering to the component parts such as the discharge wire and the grid electrode is provided. It may be added. The blower in this case is generally composed of a blower that sends air and a blower pipe (duct) that guides the air sent from the blower to a target structure such as a corona discharger and sends it out.

  Conventionally, various improvements and the like have been made for the air blower and the like so that air can be uniformly blown in the longitudinal direction of the components such as the discharge wires. In particular, as such a blower device, a configuration in which the shape of the passage space through which the air of the duct flows is formed in a special shape, or a configuration in which a rectifying plate for adjusting the direction of air flow is installed in the passage space of the duct The air blower etc. which employ | adopt another structure which is illustrated below instead of employ | adopting are proposed.

  As an air duct for guiding the air of the blower fan to the corona discharge device, a partition wall is formed in the air duct along the longitudinal direction of the corona discharge device (shield case), and the front side of the partition wall Thus, there are known a blower and a corona discharge device that employ an air duct that temporarily increases the pressure of the air flow (air flow) sent from the blower fan (Patent Document 1).

  According to Patent Document 1, according to the air blower and the corona discharge device, the air flow flowing through the duct is made uniform along the longitudinal direction of the shield case when passing through the partition wall, and becomes a uniform flow. It is shown that it will be blown into the case. Further, Patent Document 1 shows that the partition wall may be constituted by an air filter provided so as to block the flow path in the air duct.

JP-A-10-198128

  The present invention has an inlet and an outlet having different opening shapes, and after taking in air sent from a blower or the like from the inlet, the longitudinal direction portion of a long target structure to be blown with the air. As a blower pipe that is discharged from the outlet so as to flow along a direction perpendicular to the longitudinal direction through a passage space bent at at least one location, the wind speed (air volume) of air discharged from the outlet is increased. Even in this case, it is possible to provide a blower pipe capable of reducing the relative weakening of the wind speed of the air discharged from the outlet at a part of the outlet without changing the shape or structure of the passage space. The present invention provides a blower device and an image forming apparatus using a blower tube.

The blast tube of this invention (A1)
An inlet for taking in air;
It is arranged in a state facing a longitudinal portion of a long target structure to be blown by discharging air taken in from the inlet, and has a long opening shape parallel to the longitudinal portion of the target structure. And an outlet having an opening shape different from that of the inlet,
A passage portion in which a passage space for flowing air by connecting between the inlet and the outlet is formed in a shape bent at at least one place;
A plurality of restraining portions that are provided at different portions in the direction of flowing air in the passage space of the passage portion and suppress the flow of air;
As the bending passage portion, a first bending passage that is bent and extended in one direction different from the certain direction so that the passage cross-sectional area is enlarged from the middle of the introduction passage portion that allows air taken in from the inlet to flow in a certain direction. And a second bent passage portion that is bent and extended in one direction different from the one direction from the middle of the first bent passage portion,
At least one of the plurality of restraining portions blocks the passage space of the first bending passage portion in a state of crossing, and has an elongated gap extending in the transverse direction to prevent passage of air. It is provided as the most upstream restraint that enables
Among the passage portions , at least a part of the curved surface portion of the inner wall surface existing inside the bending direction between the first bending passage portion and the second bending passage portion, and a part of the plane portion existing immediately before the curved surface portion. In addition, a plurality of protrusions or depressions are provided.

  The blast tube of this invention (A2) is the blast tube of the above-mentioned invention A1, wherein at least a part of the curved surface portion and the curved surface of the inner wall surface existing inside the direction of bending between the introduction passage portion and the first bending passage portion. A plurality of protrusions or depressions are provided in a part of the plane portion existing immediately before the portion.

The blast pipe of the present invention (A 3 ) is the blast pipe of the invention A 1 or A2 , wherein a part of the curved surface portion is a portion existing on the upstream side in the direction of air flow in the curved surface portion. A part of the portion is a portion existing on the side closer to the curved surface portion of the flat surface portion.

Blower tube of the present invention (A 4), in any of the blower tube A3 from the invention A1, wherein one of the non-inhibiting portion of the most upstream among the plurality of reduction unit, a plurality of the outlet of the ventilation unit Is provided as the most downstream restraining portion that is closed by the air-permeable members dotted.

Blower tube of the present invention (A 5), in any of the blower tube A 4 from the invention A1, the target structure is one that is corona discharger.

Blower of the present invention (B1) includes a blower for sending air, and a blower tube according to any one of A 4 from the invention A1, that taking air sent from the blower from the inlet of the blower pipe It is a feature.

  The air blower of this invention (B2) is the air blower of the said invention B1, The said target structure is a corona discharger.

Furthermore, the image forming apparatus (C1) of the present invention includes a long target structure to be blown with air, and a blower for blowing air toward a longitudinal portion of the target structure,
The air blower is composed of the air blower of the invention B1.

  The image forming apparatus (C2) of the present invention is the image forming apparatus of the above-described invention C1, wherein the target structure is a corona discharger.

According to the blast pipe of the invention A1, even when the wind speed of the air discharged from the outlet is increased, the shape and structure of the passage space are not changed and the configuration of the invention is not provided. The curved surface of the inner wall surface that exists between the second bent passage portion and the middle of the first bent passage portion in the short direction substantially perpendicular to the longitudinal direction of the outlet, especially the wind speed of the air discharged from the outlet It is possible to at least reduce the relative weakening at the end close to the portion .

  In the blast pipe of the invention A2, the wind speed of the air discharged from the outlet is in the middle of the introduction passage portion and the first bending passage portion in the longitudinal direction of the outlet, compared with the case where the configuration of the invention is not provided. It is possible to reduce the relative weakening at the end near the curved surface portion of the inner wall surface existing in between.

The blower tube of the invention A 3, despite the provision of the parts necessary minimum portions providing a projection or recess, even when increasing the velocity of the air discharged from the outlet, Ya shape of the passage space Without changing the structure, it is possible to reduce the relative decrease in the wind speed of the air discharged from the outlet at a part of the outlet.

The blower tube of the invention A 4, as compared with the case without the suppression of the most downstream to the outlet, it is possible to discharge the air in a state in which unevenness of the wind speed is reduced from the outlet.

The blower tube of the invention A 5, can be compared to the case not having the constitution of the invention, blow air wind speed fluctuation is reduced with respect to the corona discharger.

  According to the blower of the invention B1, the air discharged from the outlet of the blower pipe changes the shape and structure of the passage space in the blower pipe even when the wind speed of the air discharged from the outlet is increased. In addition, it is possible to reduce the relative weakening of the wind speed of the air discharged from the outlet at a part of the outlet.

  In the air blower of the said invention B2, compared with the case where it does not have the structure of the invention, the air with which the wind speed nonuniformity was reduced can be sprayed with respect to a corona discharger from the exit of a blower pipe.

  According to the image forming apparatus of the above invention C1, the shape and structure of the passage space in the blower pipe, even when the air discharged from the outlet of the blower pipe in the blower increases the wind speed of the air discharged from the outlet. It is possible to reduce that the wind speed of the air discharged from the outlet is relatively weakened at a part of the outlet without changing the air flow, and thereby the air discharged from the outlet of the blower pipe is targeted. The structure can be sprayed with little wind speed unevenness.

  In the image forming apparatus according to the invention C2, it is possible to blow air with reduced wind speed unevenness from the outlet of the blower tube to the corona discharger as compared with the case where the configuration of the invention is not provided.

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 the schematic which shows a state when the air blower of FIG. 3 is seen from upper direction. It is sectional explanatory drawing which follows the QQ line of the air blower (air blower tube) of FIG. It is the schematic which shows a state when the exit of the ventilation pipe | tube in the air blower of FIG. 3 and its peripheral part are seen from the downward direction. It is explanatory drawing shown in the state when the ventilation pipe in the air blower of FIG. 3 is seen from upper direction. FIG. 8 is a cross-sectional explanatory view showing a part of the blower tube of FIG. 7. It is sectional explanatory drawing which follows the QQ line of the blast pipe of FIG. It is explanatory drawing which shows typically the structure of the some protrusion provided in each inner wall surface. It is explanatory drawing which shows typically the direction and state which air flows in the blast pipe of FIG. 7 (FIG. 8). It is explanatory drawing which shows typically the direction and state which air flows in the ventilation pipe of FIG. 7 (FIG. 9). It is explanatory drawing which shows typically the direction and state of the air which flow in contact with each inner wall surface provided with the some protrusion. It is a graph which shows the result when analyzing the wind speed distribution in the exit of an air duct by simulation, (a) is a comparatively large amount of air from the exit of the air duct which provided the some protrusion in the upstream inner wall part. The result in the case of discharging is shown, and (b) shows the result in the case of discharging a relatively large amount of air from the outlet of the air duct provided with a plurality of projections on the inner wall portion on the downstream side. The graph which shows the result when analyzing the wind speed distribution in the exit (when discharging a comparatively large amount of air from an exit) of the ventilation duct which provided a plurality of projections in both the upstream and downstream inner wall parts by simulation It is. It is sectional explanatory drawing which shows the principal part (when a some hollow is provided in the applicable inner wall part) of the ventilation duct which concerns on Embodiment 2. FIG. It is sectional explanatory drawing which follows the QQ line of the blast pipe of FIG. It is explanatory drawing which shows typically the structure of the some hollow provided in each inner wall surface. It is explanatory drawing which shows typically the direction and state of the air which flow in contact with each inner wall surface provided with the several hollow. It is explanatory drawing which showed typically the principal part of the other structural example (when it has an expansion type bending channel | path part). It is upper surface explanatory drawing which shows the various example of a ventilation duct. It is a graph showing the results when analyzing the wind speed state at the outlet of the air duct of the comparative example by simulation, (a) shows the results when a relatively small amount of air is discharged from the outlet of the air duct, (B) shows the result when a relatively large amount of air is discharged from the outlet of the air duct. It is a graph showing the results when analyzing the wind speed distribution at the outlet of the air duct of the comparative example by simulation, (a) shows the results when a relatively small amount of air is discharged from the outlet of the air duct, (B) shows the result when a relatively large amount of air is discharged from the outlet of the air duct.

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

[Embodiment 1]
1 to 6 show a blower tube according to Embodiment 1, a blower device using the blower tube, and an image forming apparatus. FIG. 1 shows an outline of the image forming apparatus, FIG. 2 shows a charging device that is used in the image forming apparatus and is an example of a long target structure to be blown with air by the blower tube or blower, 3 shows an outline of the blower pipe or blower, FIG. 4 shows a state when the blower of FIG. 3 is viewed from above, and FIG. 5 shows a QQ line in the blower (blower pipe) of FIG. FIG. 6 shows a state when the blower of FIG. 3 is viewed from below (exit). Arrow directions indicated by reference signs X, Y, and Z in the drawings are orthogonal coordinate axes indicating the width, height, and depth direction of the three-dimensional space assumed in each drawing.

<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 transporting 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. 9 is installed.

  The image forming unit 20 is configured using, for example, a known electrophotographic system, and includes a photosensitive drum 21 that rotates in a direction indicated by an arrow A (a clockwise direction in the drawing), and a photosensitive member. A charging device 4 that charges a peripheral surface, which is an image forming area of the drum 21, to a required potential, and light (dotted line with an arrow) based on image information (signal) input from the outside to the surface of the photosensitive drum 21 after charging. , An exposure device 23 that forms an electrostatic latent image having a potential difference, a developing device 24 that develops the electrostatic latent image into a toner image with toner, and a transfer device 25 that transfers the toner image onto a sheet 9. The cleaning device 26 mainly removes toner remaining on the surface of the photosensitive drum 21 after transfer.

  Of these, a corona discharger is used as the charging device 4. 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 has an external shape having a rectangular top plate 40a partially opened and side plates 40b and 40c hanging downward from a long side portion extending along the longitudinal direction B of the top plate 40a. A shield case (cover member) 40, 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 two end support members, respectively. The two corona discharge wires 41A and 41B that are attached while passing through the internal space of the shield case 40 and stretched substantially linearly, and the lower opening of the shield case 40 are covered with the lower opening. A grid-like grid electrode (electric field adjusting plate) 42 attached in a state of being present between the discharge wire 41 and the peripheral surface of the photosensitive drum 21 is provided. Reference numeral 40d shown in FIG. 4 and the like is a partition plate that partitions a space in which the two corona discharge wires 41A and 41B are arranged.

  Further, the charging device 4 is in a state in which the corona discharge wire 41 (41A, 41B) faces the circumferential 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 be present at least in the image formation target area along the direction. The charging device 4 is configured to apply a charging voltage to the discharge wire 41 (between the photosensitive drum 21) from a power supply device (not shown) when an image is formed.

  In addition, the charging device 4 is applied to the corona discharge wires 41 and the grid electrodes 42 with the use thereof, such as paper dust of the paper 9, discharge products generated by corona discharge, and substances (unnecessary items) such as toner external additives. As a result of adhesion and contamination, 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 is provided with a blower device 5 for abutting air against the discharge wire 41 and the grid electrode 42 in order to prevent or suppress unwanted substances from adhering to the discharge wire 41 and the grid electrode 42. ing. An opening 43 for taking in air from the blower 5 is formed on the upper surface 40 a of the shield case 40 of the charging device 4. The opening 43 is formed so that the opening shape is rectangular. The details of the blower 5 will be described later.

  The sheet feeding device 30 accommodates a plurality of recording sheets 9 of a required size and type used for forming an image in a stacked state, and a sheet accommodating body 31 such as a tray type or a cassette type, and the sheet accommodating A feeding device 32 that feeds the recording paper 9 accommodated in the body 31 one by one toward the conveyance path is provided, and the paper 9 is fed one by one when the paper feeding time comes. A plurality of paper containers 31 are provided according to the usage mode. A one-dot chain line with an arrow in FIG. 1 indicates a conveyance path through which the recording paper 9 is mainly conveyed. The recording paper conveyance path is composed of 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 rotating in contact with a required pressure so as to substantially follow the axial direction of the heating rotator 37 are provided. The fixing device 35 performs fixing by introducing and passing the recording paper 9 after the toner image is transferred to a fixing processing unit formed between the heating rotator 37 and the pressure rotator 38. .

  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 an example.

  In the image forming apparatus 1, when the control device or the like 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. The At this time, the charging device 4 generates a corona discharge in a state where a charging voltage is applied to the corona discharge wire 41 and an electric field is formed between the discharge wire 41 and the peripheral surface of the photosensitive drum 21. 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, exposure based on image information is performed from the exposure device 23 on the peripheral surface of the charged photosensitive drum 21 to form an electrostatic latent image having a required potential difference. 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 in the required polarity supplied from the developing roll 24a, and the toner image is developed. As visualized.

  Next, when the toner image formed on the photoconductive drum 21 is conveyed to the transfer position facing the transfer device 25 by the rotation of the photoconductive drum 21, it is supplied from the paper supply device 30 through the conveyance path at this timing. The recording device 9 is transferred by the transfer device 25. The peripheral surface of each photosensitive drum 21 after the transfer is cleaned by a 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 added to the heating rotator 37 in the fixing device 35. The toner image is melted and fixed on the recording paper 9 by being heated and pressurized when passing through the fixing processing portion between the pressure rotating body 38 and the pressure rotating body 38. 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) formed outside the housing 10 and 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.

<Blower device>
Next, the blower 5 will be described.

  As shown in FIGS. 1 and 3, the blower 5 includes a blower 50 having a rotating fan that sends air, and a blower duct that takes in the air sent from the blower 50 and guides it to the charging device 4 to be blown and discharges it. 51.

  The blower 50 is for sending a required amount of air to the blower duct 51. For example, a radiant flow type blower fan is used and driven and controlled so as to send the required amount of air. As shown in FIGS. 3 to 6, the air duct 51 includes an inlet 52 for taking in air sent from the blower 50 and a longitudinal direction B of the long charging device 4 to which air taken in from the inlet 52 should be blown. Between the inlet 52 and the outlet 53, and an outlet 53 that is disposed in a state facing the portion (the upper surface 40a of the shield case 40) and discharges the air so as to flow along a direction orthogonal to the longitudinal direction B. It has a shape having a passage portion (main body portion) 54 in which a passage space 54a for flowing air is formed.

  The passage portion 54 of the air duct 51 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 thereof is closed, and the whole extends linearly along the longitudinal direction of the outlet 53 (longitudinal direction B of the charging device 4). It is the square-tube-shaped channel | path part formed in this way. The first bent passage portion 54B is substantially horizontal (in a direction substantially parallel to the coordinate axis X) so that the width of the passage space is expanded from a portion (in the middle) near the other end of the introduction passage portion 54A to enlarge the passage cross-sectional area. 2 is a rectangular tube-shaped bent passage portion formed so as to be bent and extend substantially at a right angle. The second bending passage portion 54C is bent in the vertical direction (a direction substantially parallel to the coordinate axis Y) from the one end portion of the first bending passage portion 54B in a state where the width of the passage space remains the same, and is applied to the charging device 4. It is the bending channel | path part formed so that it might extend toward. An outlet 53 having an opening shape slightly narrower than the cross-sectional shape of the passage space at the end portion is formed at the end portion of the second bent passage portion 54C (however, the length in the longitudinal direction of the rectangular shape is substantially the same). is there.). Further, the passage spaces 54a of the first bending passage portion 54B and the second bending passage portion 54C are both set to have substantially the same width (dimension along the longitudinal direction B).

  The inlet 52 of the air duct 51 is formed so that the opening shape is substantially square at one end of the introduction passage portion 54A (FIGS. 3 and 5). A connection duct 55 is attached to the inlet 52 to connect the blower 50 and send air from the blower 50 to the inlet 52 of the blower duct 51 (FIGS. 3 and 4). On the other hand, the outlet 53 of the air duct 51 is formed so that the opening shape thereof is a long opening shape (for example, a rectangle) parallel to the portion in the longitudinal direction B of the charging device 4. For this reason, the air duct 51 has a relationship in which the inlet 52 and the outlet 53 are formed in different opening shapes. In addition, even when the inlet 52 and the outlet 53 have the same shape, when the opening areas are different from each other (when they are similar in shape), they are included in the relationship of being formed with different opening shapes. . Further, as shown in FIG. 7 and the like, the inlet 52 protrudes by a required dimension G outside the one end 53a in the longitudinal direction (B) of the outlet 53 having a long opening shape. It is formed with.

  Here, in the air duct 51 having the inlet 52 and the outlet 53 having different opening shapes, there is a portion where the cross-sectional shape of the passage space 54 a is changed in the middle of the passage portion 54 connecting the inlet 52 and the outlet 53. To do. Incidentally, in this blower duct 51, the cross section of the passage space 54a formed of a substantially square shape of the introduction passage portion 54A due to the presence of a bent portion (first bending passage portion 54B) in the passage portion 54 (the passage space 54a). The shape is changed to the cross-sectional shape of the passage space 54a formed of a rectangle extending only in the horizontal direction (the height does not change) in the first bent passage portion 54B. In other words, the cross-sectional shape (passage cross-sectional area) of the passage space 54a of the first bent passage portion 54B is a cross-sectional shape that is abruptly wider than the cross-sectional shape of the passage space 54a of the introduction passage portion 54A.

  Further, in the case of the air duct 51 in which such a portion where the cross-sectional shape of the passage space 54a changes is present, the air flow is disturbed in the portion where the cross-sectional shape changes, such as separation or vortex. Therefore, even if air having a uniform wind speed is taken in, the air speed from the outlet 53 tends to be uneven. Thus, the tendency that the air speed of the air exiting from the outlet 53 is finally non-uniform is that the direction in which the air flows (progresses) in the air duct 51 changes regardless of the change in the cross-sectional shape of the passage space 54a. That is, when the passage space 54a has a shape bent in one direction or a shape bent so as to spread on both sides, the same occurs. Furthermore, the tendency of the air velocity of the air exiting from the outlet to be ultimately non-uniform occurs more prominently when the cross-sectional shape of the passage space 54a changes and the direction in which the air flows (travel) changes.

  21a to 21c show typical examples 510A to 510C of air ducts in which the inlet 52 and the outlet 53 are formed in different opening shapes, and in the drawing, the air taken into the inlet 52 in each duct 510 thereof. Each state of the wind speed and the wind speed of the air exiting from the outlet 53 is indicated by the length of the arrow. In FIG. 21, each air duct 510 is shown as viewed from the upper surface side. Further, in the figure, when the lengths of the arrows are the same, it indicates that the wind speed is the same, and when the lengths are different, it indicates that the wind speed is different. Furthermore, the dotted line in a figure has shown the passage space (the inner wall surface which forms) of each duct.

  Incidentally, in the air ducts 510B and 510C shown in FIGS. 21b and 21c, the air flow direction is changed in the middle (the passage space 54a is bent in the middle) and the sectional shape and sectional area of the passage space are changed. It is also a configuration example in which at least one of them is changed. In addition, the air duct 510D shown in FIG. 21d is a configuration example in which the inlet 52 and the outlet 53 are formed in the same opening shape (and the same opening area), and only the direction of flowing the air is changed in the middle. It is a duct. Further, as shown in FIG. 21a, the air duct 510A having a configuration in which the passage portion is bent so as to spread on both sides on the downstream side in the air flow direction and the passage cross-sectional area is gradually enlarged is also in the present invention. It will be included in the category of the blower duct of the blower 5.

  Therefore, the air duct 51 in the air blower 5 has at least one passage space 54a for connecting the inlet 52 and the outlet 53 to flow air as shown in FIGS. On the premise that the air duct is provided with the passage portion 54 formed in a shape bent in one direction at a location), and the air flows in different portions in the direction in which the air in the passage space 54a of the passage portion 54 flows. Two restraining portions 61 and 62 for restraining are provided.

  One restraining part 61 of the two restraining parts crosses a part of the first bending passage part 54B into the first bending passage part 54B corresponding to the bent part of the passage space 54a of the passage part 54. In addition to being blocked in this state, an elongate gap 63 extending in the transverse direction D is provided to allow air to pass therethrough and is provided as the “upstreammost suppression portion”.

  In the first embodiment, the most upstream restraining portion 61 does not change the outer shape of the first bent passage portion 54B, and a plate-like blocking member 64 is provided in the passage space 54a of the bent passage portion 54B. It arrange | positions so that it may be in the state which crosses with a clearance gap only with respect to the bottom part in cross-sectional shape.

  Specifically, as shown in FIG. 5 and the like, the blocking member 64 blocks in a state where the upper side of the cross-sectional shape in the passage space 54a of the first bent passage portion 54B is crossed, and the lower end of the blocking member The portion 64a is arranged so as to be in a state of having a required interval H with respect to the bottom of the cross-sectional shape of the passage space 54a, and thus there is a long and narrow gap 63 extending in a direction transverse to the lower portion of the passage space 54a. Is forming. At this time, the blocking member 64 is located at the end of the passage space 54a of the first bent passage portion 54B on the upstream side of the air flowing direction R2 in the first bent passage portion 54B, with respect to the air flow direction R2. They are arranged in a state of being transversely crossed along a transverse direction D that is a direction substantially perpendicular (a direction substantially parallel to the longitudinal direction B of the charging device 4).

  Further, as shown in FIG. 7 and the like, the blocking member 64 is an imaginary straight line (two-dot chain line) that connects both end portions 63a and 63b in the transverse direction D of the gap 63 formed by the blocking member 64 of the most upstream suppressing portion 61. ) VL is provided at a position downstream of the inlet 52 in the direction R2 where the air in the first bent passage portion 54B should flow from the inner end portion 52a closer to the first bent passage portion 54B. . At this time, the blocking member 64 has an upstream end portion (substantially the same as the virtual straight line VL) required on the downstream side in the direction R2 in which the air in the first bent passage portion 54B should flow from the inner end portion 52a of the inlet 52. Are arranged in a state of being shifted by a distance N of.

  Arrangement position (distance N shifted to the downstream side of the air flow direction R2) of the blocking member 64 constituting the most upstream suppressing portion 61, height H, path length M and width (length in the longitudinal direction) of the gap 63 ) W is selected and set from the viewpoint of making the wind speed of the air flowing from the introduction passage portion 54A into the first bending passage portion 54B as uniform as possible. These values are set in consideration of the dimensions (capacity) of the duct 51 and the flow rate per unit time of air to be passed through the duct 51 or the charging device 4.

  For example, it is preferable that the lower limit of the distance N corresponding to the arrangement position of the blocking member 64 is at least 5 mm. On the other hand, the upper limit value of the distance N is set, for example, within a range in which the effect of uniforming the wind speed by the most upstream suppressing unit 61 can be obtained. Further, the height H of the gap 63 is not limited to the same dimension in the width direction, and can be set to a dimension that is uniformly or partially changed from the above viewpoint. Such a blocking member 64 is formed by integrally molding the same material as that of the duct 51, or is formed of a material different from that of the duct 51.

  Further, as shown in FIG. 5 and FIG. 6, the remaining restraining portions 62 of the two restraining portions are provided with an outlet 53 that is an opening at the end portion in the passage space 54a of the second bending passage portion 54C. 71 is provided as a “most downstream restraint portion” that is closed by air-permeable members 70 dotted with dots.

  As shown in FIGS. 5 and 6, each of the plurality of ventilation portions 71 is a through hole that extends 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 are arranged in four rows at the same interval in the short direction C perpendicular to the longitudinal direction. They are arranged to exist. As a result, the plurality of vent holes 71 are formed so as to be scattered throughout the passage space at the end of the second bent passage portion 54C or the entire 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. Further, the plurality of ventilation portions 71 are preferably formed so as to be scattered substantially uniformly (with a substantially constant density) with respect to the opening region of the outlet 53, but the air flowing out from the outlet 53 As long as it does not appear uneven, it may be formed so as to exist in a slightly dense state.

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

  Further, the air duct 51 in the air blower 5 has the shortest side wall surface portion 54As (the inner wall surface) from the inlet 52 of the introduction passage portion 54A to the upstream end portion in the direction R2 in which the air flows in the first bending passage portion 54B. Is formed by one plane. That is, the side wall surface portion 54As (the inner wall surface) from the inner end portion 52a of the inlet 52 to the upstream end portion of the first bending passage portion 54B is formed as one continuous flat surface having no bent portion.

  By the way, according to the study by the present inventors, in this blower 5, the wind speed of the air discharged from the outlet 53 of the blower duct 51 (the blower duct 510 having a configuration in which the projection 81 or the recess 82 described later is not provided). If it is used under a condition where the (air volume) is relatively small, the air flow state is taken into the introduction passage portion 54A from the inlet 52 as schematically shown by a two-dot chain line with an arrow in FIG. 22a. Low-speed air (Ea) passes in a state of being close to the end portion 63a that is closer to the inlet 52 in the gap 63 of the most upstream suppressing portion 61, and finally to the side of the outlet 53 that is closer to the inlet 52. It has been confirmed that the reduction of the wind speed of the air discharged from the end 53a is suppressed as compared with the wind speed of the air discharged from the other outlet portions (see FIG. 23a).

  However, in the case of using under the condition that the wind speed (air volume) of the air discharged from the outlet 53 of the air duct 51 (510) is increased, the state in which the air flows is schematically shown by a two-dot chain line with an arrow in FIG. As shown specifically, the high-speed air (Eb) taken into the introduction passage portion 54A from the inlet 52 moves away from the end portion 63a that is closer to the inlet 52 in the gap 63 of the most upstream suppressing portion 61. The air velocity when the air is finally discharged from the end portion 53a on the side close to the inlet 52 of the outlet 53 is reduced as compared with the air velocity of the air discharged from the other outlet portions. (See FIG. 23b). Incidentally, the case where the wind speed of the air discharged from the outlet 53 is increased is a case where the wind speed when discharged from the outlet 53 is set to a value of 10 m / second or more, for example.

  Therefore, in the blower duct 51 in the blower 5, as shown in FIGS. 8 to 9 and the like, between the introduction passage portion 54 </ b> A and the first bending passage portion 54 </ b> B and between the first bending passage portion 54 </ b> B and the second bending passage portion. 54C, at least a part of the curved surface portions 55C and 56C of each inner wall surface 55 and 56 existing inside the bending direction, and a part of the flat surface portions 55F and 56F immediately before the curved surface portions 55C and 56C. A plurality of protrusions 81A and 81B are provided.

  As shown in FIG. 8 and the like, the inner wall surface 55 is a side surface portion that exists inside the direction J1 that bends between the introduction passage portion 54A and the first bending passage portion 54B. Further, the curved surface portion 55C of the inner wall surface 55 is a portion formed in a curved surface shape from a point where the inner wall surface 55 (side surface portion) starts to bend in the bending direction J1 to a point where the bending ends. Furthermore, the flat surface portion 55F of the inner wall surface 55 is a portion formed in a planar shape of the side surface portion that continuously exists from the upstream end portion of the curved surface portion 55C in the air flow direction. This corresponds to the side surface from the point where the portion 55C begins to bend to the introduction passage 54A (the inlet corner 52a on the side closer to the outlet 53).

  On the other hand, as shown in FIG. 9 and the like, the inner wall surface 56 is a bottom surface portion that exists on the inner side in the bending direction 2 between the first bending passage portion 54B and the second bending passage portion 54C. Further, the curved surface portion 56C of the inner wall surface 56 is a portion formed in a curved surface shape from the point where the inner wall surface 56 (bottom surface portion) starts to bend in the bending direction J2 to the point where the bending ends. Furthermore, the flat surface portion 56F of the inner wall surface 56 is a portion formed in a planar shape of the bottom surface portion that continuously exists from the upstream end portion of the curved surface portion 56C in the air flow direction. This is the bottom surface portion from the point where the portion 56C begins to bend to the upstream end of the first bending passage portion 54B in the direction in which the air flows (the point where the curved portion 55C finishes bending).

  As shown in FIGS. 8 and 9, the protrusions 81 </ b> A and 81 </ b> B are component parts that protrude in the direction from the inner wall surfaces 55 and 56 into the passage space 54 a, and are formed on the inner wall surfaces 55 and 56. A part of the air flowing in contact becomes a part that causes a small turbulent flow. In the first embodiment, as the protrusions 81A and 81B, a plurality of protrusions extending linearly along a direction substantially perpendicular to the air flow direction are provided so as to exist at a required interval. As shown in FIGS. 8 to 10, the protrusions 81 </ b> A and 81 </ b> B formed of the protrusions have a cross-sectional shape of a rectangle, a semicircle, a semipolygon diameter, or the like. Further, with respect to the protrusion height h, width w, and interval p of the protrusions 81A and 81B, the original flow of air is not obstructed (such as changing the wind direction to an inappropriate direction or greatly blocking the flow). As a premise, it is arbitrarily set in consideration of the wind speed of air, the degree of turbulence generation, and the like. Further, the protrusions 81A and 81B can be integrally formed as a part of the passage portion 54 (main body portion) (the shape of the inner wall surface) of the air duct 51. It is possible to produce it so as to be provided as a component (projection) separate from the portion 54 (main body portion).

  Further, at least a part of the curved surface portions 55C and 56C of the inner wall surfaces 55 and 56 on which the protrusions 81A and 81B are actually provided are bent along the curved surface portions 55C and 56C as much as possible so that air flows. From the viewpoint of generating turbulent flow, for example, it is preferable that each of the curved surface portions 55C and 56C is a half portion (upstream portion) existing upstream from an intermediate point in the air flow direction. Further, at least a part of the flat surface portions 55F and 56F of the inner wall surfaces 55 and 56 where the protrusions 81A and 81B are actually provided are as far as possible along the curved surface portions 55C and 56C continuing from the flat surface portions 55F and 56F. From the viewpoint of generating turbulent flow so that air flows by bending in a curved direction (it is difficult to separate at each curved surface portion 55C, 56C), for example, it exists on the side closer to each curved surface portion 55C, 56C among the respective flat surface portions 55F, 56F. More specifically, it exists on the side closer to each curved surface portion 55C, 56C when equally divided into one third (1/3) of the entire length of each planar portion 55F, 56F. It is preferable that it is a part to do.

  Incidentally, in the first embodiment, the protrusions 81A are provided in the upstream portion of the curved surface portion 55C of the inner wall surface 55 and the half portion existing immediately before the flat surface portion 55F. Further, the protrusion 81B is provided on almost the entire area of the curved surface portion 56C of the inner wall surface 56 and on almost the entire area of the flat surface portion 56F. In particular, the flat surface portion 56F of the inner wall surface 56 is a portion that overlaps the region where the gap 63 of the most upstream suppressing portion 61 exists.

  Hereinafter, the operation of the blower 5 will be described.

  In the blower device 5, when the drive setting time such as during the image forming operation is reached, the blower 50 is first rotationally driven to send out a required amount of air. As shown in FIG. 4, the air (E) sent from the started blower 50 is taken into the passage space 54 a from the inlet 52 of the blower duct 51 through the connection duct 55.

  As shown in FIGS. 11 and 12, the air (E) taken in from the inlet 52 of the air duct 51 advances so as to flow in a state along the direction R1 in which the air should flow in the passage space 54a of the introduction passage portion 54A. After that (E1), the flow finally changes from the introduction passage portion 54A to the passage space 54a of the first bending passage portion 54B that bends substantially downward in the horizontal direction (E1a, E1b).

  At this time, as shown in FIG. 13a, the air (E1b) of the portion flowing in contact (approaching) the inner inner wall surface (side surface portion) 55 between the introduction passage portion 54A and the first bending passage portion 54B, When passing through a plurality of projections 81A provided in the entire area of the flat surface portion 55F and the curved surface portion 55C in the inner wall surface 55, a part of the air is behind (downstream) the projections 81A as illustrated by dotted arrows. Turbulent flow that vortexes so as to enter the hollow space on the side), and proceeds while curving toward the curved surface portion 55C (see the progress state of the solid arrow).

  This is because the portion of the air (E1b) flowing in contact with (approaching) the inner wall surface 55 becomes a turbulent boundary layer in the portion of the inner wall surface 55 provided with the plurality of protrusions 81A, and the turbulent flow in the turbulent boundary layer It is presumed that the separation point that separates when passing through the curved surface portion 55C of the inner wall surface 55 gradually moves and shifts to the downstream side of the air flow due to the diffusibility of air due to the generation. For reference, in FIG. 13a, assuming an inner wall surface 55 provided with no protrusion 81A, when air traveling in the vicinity of the inner wall surface 55 flows (after peeling from the curved surface portion 55C of the inner wall surface 55). The flow direction of the air flowing in the state closest to the curved surface portion 55c of the inner wall surface 55 is indicated by a two-dot chain line arrow.

  Subsequently, the air (E1a, E1b) that flows so as to move to the first bending passage portion 54B is, as shown in FIG. 12, the uppermost flow suppressing portion 61 that exists at the upstream end of the first bending passage portion 54B. While being blocked by the blocking member 64, it finally flows through the gap 63 of the most upstream suppressing portion 61.

  At this time, the air (E2) passing through the gap 63 of the most upstream suppressing portion 61 and flowing into the passage space 54a of the first bending passage portion 54B is in a state where the flow is suppressed by the most upstream suppressing portion 61. (A state in which the pressure has increased), and flows in a uniform state from the gap 63. In addition, the air (E2) when flowing into the passage space 54a of the first bent passage portion 54B flows into the gap 63 of the most upstream suppressing portion 61 from the gap 63 of the suppressing portion 61 as shown in FIG. However, it is aligned in a direction substantially along the direction R2 in which the air in the passage space 54a of the first bending passage portion 54B should flow (this direction R2 is also a direction substantially perpendicular to the longitudinal direction B of the outlet 53). At this time, in particular, the air (E1b) that flows close to the inner wall surface 55 having the curved surface portion 55C flows along the curved surface portion 55C as much as possible, and is closer to the inlet 52 of the first bent passage portion 54B. As you approach the edge you become, go ahead.

  Subsequently, the air (E2) that has flowed into the passage space 54a of the first bent passage portion 54B continues in a state of being bent in a substantially perpendicular direction from the first bent passage portion 54B downward. It moves to the passage space 54a of 54C. As shown in FIG. 12, the air (E2) flowing into the passage space 54a of the second bending passage portion 54C is a second bending passage portion having a larger volume than the passage space 54a of the introduction passage portion 54A and the space of the gap 63. By flowing in a state (E2a, E2b) so as to be diffused into the passage space 54a of 54C, it stays in the passage space 54a of the second bending passage portion 54C, and the unevenness of the wind speed is reduced.

  At this time, the air (E2b) in the portion flowing between the inner wall surface (bottom surface portion) 56 between the first bent passage portion 54B and the second bent passage portion 54C in contact (approaching) is as shown in FIG. 13b. In addition, when passing through the plurality of protrusions 81B provided on the entire area of the flat surface portion 56F and the entire surface of the curved surface portion 56C on the inner wall surface 56, a part of the air is behind the protrusions 81B (as illustrated by dotted arrows). It becomes a turbulent flow that winds in a vortex so as to enter the depression space on the downstream side, and proceeds while bending so as to approach the curved surface portion 56C (see the progress state of the solid arrow).

  This is because the portion of the air (E2b) flowing in contact with (approaching) the inner wall surface 56 becomes a turbulent boundary layer in the inner wall surface 56 portion provided with the plurality of protrusions 81B, and the turbulent flow in the turbulent boundary layer It is assumed that the separation point that separates when passing through the curved surface portion 56C of the inner wall surface 56 gradually moves and shifts to the downstream side of the air flow due to the diffusibility of air due to the generation. For reference, in FIG. 13b, assuming an inner wall surface 56 not provided with a protrusion 81B, when air traveling in the vicinity of the inner wall surface 56 flows (after peeling from the curved surface portion 56C of the inner wall surface 56). The flow direction of the air flowing in the state closest to the curved surface portion 56c of the inner wall surface 56 is indicated by a two-dot chain line arrow.

  Finally, as shown in FIG. 12, the air (E2) that flows into and stays in the second bending passage portion 54C passes through the most downstream suppressing portion 62 provided at the outlet 53 serving as a terminal portion of the bending passage portion 54C. Blows out from the outlet 53 in a state (E3) in which the traveling direction is aligned after passing through a plurality of ventilation portions (holes) 71 of the breathable member 70 that constitutes (see the direction and length of the arrow E3 in FIG. 12). ).

  At this time, the air (E3) blown out from the outlet 53 passes through the plurality of ventilation portions 71 of the breathable member 70 that is relatively narrower than the opening area of the outlet 53, and thus the flow is suppressed. (At this time, the pressure is also increased) and it is sent out. Further, the air (E3) blown out from the outlet 53 is scattered over the entire opening area of the outlet 53 and passes through the plurality of ventilation portions 71 formed under the same conditions, so that the area is substantially close to the opening shape of the outlet 53. And is fed out from the outlet 53 in a uniform state. Furthermore, the air (E3) blown out from the outlet 53 is sent out in a state where the blowing direction is aligned in a direction substantially orthogonal to the longitudinal direction of the outlet 53. In particular, the air (E2b) flowing close to the inner wall surface 56 having the curved surface portion 56C flows in a state along the curved surface portion 56C as much as possible, and is closer to the inlet 52 of the second bent passage portion 54B. You will approach the edge and proceed.

  As described above, the air (E3) exiting from the plurality of ventilation portions 71 of the air-permeable member 70 in the most downstream restraint portion 62 is sent out with its traveling direction aligned in a direction substantially perpendicular to the longitudinal direction of the outlet 53. , The wind speed is almost uniform. In addition, the wind speed of the air (E3) exiting from the outlet 53 is substantially uniform in the longitudinal direction (B) of the opening shape (rectangular shape) of the outlet 53, and in addition, the wind speed is short substantially perpendicular to the longitudinal direction (B). In the hand direction C (FIG. 5, FIG. 6 and the like), the state is almost uniform.

  In the case of the air duct 51, a plurality of protrusions 81A and 81B are provided on both the inner wall surfaces 55 and 56, respectively, so that the air finally discharged from the outlet 53 is in the longitudinal direction of the outlet 53 ( B) the wind speed at the end 53a close to the inlet 52 (which also becomes the end close to the inner wall surface 55) becomes relatively weak with respect to the wind speed of the other parts, and the outlet 53 The wind speed at the end 53c on the Pre position side (which also becomes the end near the inner wall surface 56) close to the inlet 52 in the short side direction C becomes the wind speed at the end on the opposite Post position side. On the other hand, the relative weakening is reduced. This effect can be similarly obtained even when the wind speed of the air discharged from the outlet 53 is increased (see FIGS. 14a and 15).

  As a result, the air discharged from the outlet 53 is discharged in a state in which both the wind speed unevenness in the entire longitudinal direction of the outlet 53 and the wind speed unevenness in the entire short direction are further reduced. Incidentally, in this air duct 51, even when the wind speed of the air discharged from the outlet 53 is increased, the longitudinal direction of the outlet 53 is not changed without changing the shape or structure of the passage space 54a of the passage portion 54. It is possible to discharge in a state in which the unevenness of the wind speed and the unevenness of the wind speed in the short direction are reduced.

  The air (E3) sent out from the outlet 53 of the air duct 51 is blown into the case 40 through the opening 43 formed in the upper surface 40a of the shield case 40 of the charging device 4, as shown in FIG. Two corona discharge wires 41A and 41B arranged in a space partitioned by a partition wall 40d existing in the center of the case 40, and a grid electrode attached so as to exist in a lower opening of the case 40 42 is sprayed.

  At this time, the air blown to the corona discharge wires 41A and 41B and the grid electrode 42 comes out from the outlet 53 at substantially the same wind speed in both the longitudinal direction B and the short direction C of the outlet 53 of the blower duct 51. The discharge wires 41A and 41B and the grid electrode 42 are blown in a substantially equal state.

  As a result, unnecessary materials such as paper dust, toner external additives, and discharge products that are to adhere to the two discharge wires 41A and 41B and the grid electrode 42 can be kept away from the discharge wires and the grid electrode. . As a result, it is possible to prevent the charging performance from being deteriorated due to sparsely adhering unnecessary materials to the discharge wires 41A and 41B and the grid electrode 42 in the charging device 4, and the peripheral surface of the photosensitive drum 21 can be prevented. It becomes possible to charge more uniformly (uniformly in both the axial direction and the circumferential direction along the rotational direction A). In addition, the toner image formed by the image forming unit 20 including the charging device 4 and the image finally formed on the paper 9 cause image quality defects (density unevenness, etc.) due to charging defects such as uneven charging. Can be obtained as a good image.

<Test>
Next, a test regarding performance characteristics (wind velocity distribution at the outlet 53 of the air duct 51) performed using the air blower 5 will be described.

  The test is an analysis result by computer simulation, and air having an air volume at which the average wind speed from the outlet 53 of the air duct 51 having the following configuration is a required value is introduced from the blower 50, and the longitudinal direction of the outlet 53 at that time The wind speed distribution in (B) was calculated. As shown in FIG. 12, the wind speed includes an end position P1 (pre position) located on the upstream side in the rotation direction A of the photosensitive drum 21 at the outlet 53 and an end position P2 (post) located on the downstream side in the rotation direction A. The wind speed obtained at each position in the longitudinal direction B of the outlet 53 was calculated.

The entire shape of the air duct 51 is as shown in FIG. 3 to FIG. 7, the inlet 52 has a substantially square opening shape of 22 mm × 23 mm, and the outlet 53 has a rectangular shape of 17.5 mm × 350 mm. It was set as the ventilation duct which is an opening shape. Further, the most upstream suppressing portion 61 has a height of the gap 63 at a position that is shifted from the one end portion 52a of the inlet 52 to the downstream side in the air flow direction R2 of the first bending passage portion 54B by the dimension N = 6 mm. It was set so that the length H was inclined within a range of 1 to 2 mm, the path length M was 8 mm, and the width W was 345 mm. Further, the most downstream restraining part 62 has a porous member 70 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 ). Was set up to be configured using.

  Further, the air duct 51 has an inlet 52 (one end where the inlet 52 of the introduction passage portion 54A is present) of the introduction passage portion 54A in which the dimension 53 of about 50 mm protrudes outside the one end portion 53a of the outlet 53. It was supposed to be formed at one end (FIG. 7). The curved surface portion 55C of the inner wall surface 55 is set to a cylindrical curved surface with a curvature radius of 3 mm, and the curved surface portion 56C of the inner wall surface 56 is set to a cylindrical curved surface with a curvature radius of 1 mm.

  Further, as the air duct 51, the air duct 51A provided with a plurality of projections 81A over the entire curved surface portion 55C and the flat surface portion 55F of the inner wall surface 55, and the curved surface portion 56C and the flat surface portion 56F of the inner wall surface 56 over the entire surface. The air duct 51B provided with a plurality of protrusions 81B, and the plurality of protrusions 81A are provided over the entire curved surface portion 55C and the flat surface portion 55F of the inner wall surface 55, and the plurality of protrusions 81A are provided over the entire curved surface portion 56C and the flat surface portion 56F of the inner wall surface 56. Three types of the air duct 51C provided with the protrusion 81B were prepared as examples. Incidentally, the air duct 51C substantially corresponds to the air duct 51 according to the first embodiment.

  As the protrusions 81A and 81B, the cross-sectional shape is a rectangular shape, and as shown in FIG. 10, the protrusions having a protrusion height h of about 1 mm and a width w of about 0.5 mm are separated by a distance p of about 1 mm. What was provided in the state which opened was set. At this time, the number of protrusions 81A was 10 in total, and the number of protrusions 81B was 8 in total.

  For reference, an air duct 510 having a configuration in which the projections 81A and 81B are not provided on any of the curved surface portion 55C and the flat surface portion 55 of the inner wall surface 55 and the curved surface portion 56C and the flat surface portion 56F of the inner wall surface 56 is provided. Prepared as a comparative example.

  For the air duct 510 of the comparative example, a relatively small amount of air having an average wind speed of about 7 m / sec is discharged from the outlet 53, and a relatively large amount of air having an average wind speed of about 15 m / sec is discharged from the outlet 53. In the case of discharging from the air outlet, the wind speed distribution of the air (E3) discharged from the outlet 53 was examined. FIG. 23a shows the result of the wind speed distribution when a relatively small amount of air is discharged, and FIG. 23b shows the result of the wind speed distribution when a relatively large amount of air is discharged.

  As is clear from the results of this comparative example, in the air duct 510 not provided with the protrusion 81, when a relatively small amount of air is discharged, both the longitudinal direction B and the short direction C of the outlet 53 are used as the wind speed distribution. An almost uniform uniformity can be obtained. On the other hand, when a relatively large amount of air is discharged, the wind speed at the end 53a (the side in which the longitudinal distance is close to zero) that is closer to the inlet 52 in the longitudinal direction B of the outlet 53 is relatively higher. Further, the wind speed at the end 53c on the Pre position side, which is closer to the inlet 51 in the short direction C of the outlet 53, is also relatively reduced, and the uniformity of the wind speed distribution in the entire outlet 53 is reduced. End up.

  Next, regarding the air ducts 51A, 51B, 51C of the embodiment, when a relatively large amount of air having an average wind speed of about 15 m / sec is discharged from the outlets 53, the wind speed distribution of the air (E3) blown out from the respective outlets 53 I investigated each. The result of the wind speed distribution of the air duct 51A is shown in FIG. 14a, and the result of the wind speed distribution of the air duct 51B is shown in FIG. 14b. Moreover, the result of the wind speed distribution of the wind speed duct 51C is shown in FIG.

  As is clear from the results shown in FIG. 14a, in the case of the air duct 51A provided with a plurality of protrusions 81A on the inner wall surface 55, a substantially constant uniformity is obtained as the wind speed distribution in the longitudinal direction B of the outlet 53, In the short direction C of the outlet 53, the wind speed at the end portion 53c on the Pre position side is relatively lower than the wind speed at the end portion on the Post position side. Further, as is apparent from the result shown in FIG. 14b, in the case of the air duct 51B provided with a plurality of protrusions 81B on the inner wall surface 56, a substantially constant uniformity is obtained as the wind speed distribution in the short direction C of the outlet 53. On the other hand, in the longitudinal direction B of the outlet 53, the wind speed at the end 53a that is closer to the inlet 52 is relatively reduced.

  Further, as is apparent from the results shown in FIG. 15, in the case of the air duct 51C provided with a plurality of protrusions 81A and 81B on both the inner wall surface 55 and the inner wall surface 56, the longitudinal direction B of the outlet 53 is shown as the wind speed distribution. In both the lateral direction C and the uniform direction, good uniformity can be obtained.

[Embodiment 2]
FIG.16 and FIG.17 shows the principal part of the ventilation pipe (air blow duct) which concerns on Embodiment 2. FIG.

  The blower duct 51D according to the second embodiment is a blower according to the first embodiment, except that the inner wall surfaces 55 and 56 are changed to be provided with a plurality of depressions 82A and 82B instead of the plurality of protrusions 81A and 81B. The structure is the same as that of the duct 51. The air duct 51D is similarly applied to the air blower 5 and the image forming apparatus 1 described in the first embodiment.

  The recesses 82A and 82B in the air duct 51D are constituent parts having a shape that is recessed from the inner wall surfaces 55 and 56 in the opposite direction to the inside of the passage space 54a, as shown in FIGS. A part of the air flowing in contact with the inner wall surfaces 55 and 56 becomes a part that causes a small turbulent flow. In the second embodiment, as the recesses 82A and 82B, a plurality of grooves extending linearly along a direction substantially perpendicular to the air flow direction are provided so as to exist at a required interval. As shown in FIGS. 16 to 18, the recesses 82A and 82B formed by the grooves have a cross-sectional shape of a rectangle, a semicircle, a semi-polygon, or the like. Further, with respect to the depth d, width w, and interval p of the recesses 82A and 82B, the original flow of air is not obstructed (such as changing the wind direction to an inappropriate direction or greatly blocking the flow). As a premise, it is arbitrarily set in consideration of the wind speed of air, the degree of turbulence generation, and the like. Further, the recesses 82A and 82B can be manufactured by being integrally formed as a part (inner wall surface shape) of the passage portion 54 (main body portion) of the air duct 51D, for example.

  And the operation | movement of the air blower 5 using this air duct 51D is the same as the operation | movement content of the air blower 5 using the air duct 51 which concerns on Embodiment 1 fundamentally, However, It differs a little in the following points. .

  That is, first, the air (E) taken from the inlet 52 of the air duct 51D has advanced so as to flow in the state along the direction R1 in which the air should flow in the passage space 54a of the introduction passage portion 54A, as shown in FIG. After (E1), the flow finally changes from the introduction passage portion 54A to the passage space 54a of the first bending passage portion 54B that bends substantially downward in the horizontal direction (see FIGS. 11 and 12). At this time, the air (E1b) flowing in contact (approaching) the inner inner wall surface (side surface portion) 55 between the introduction passage portion 54A and the first bending passage portion 54B is shown in FIG. 19a (see FIG. 13a). As shown in FIG. 4, when passing through a plurality of dents 82A provided in the entire area of the flat surface portion 55F and the curved surface portion 55C of the inner wall surface 55, each of the protrusions is illustrated by a dotted arrow. It becomes a turbulent flow that spirals so as to enter the recessed space behind (downstream side) 81A, and proceeds while curving so as to approach the curved surface portion 55C (see the progress state of the solid arrow).

  This is because the portion of the air (E1b) flowing in contact with (approaching) the inner wall surface 55 becomes a turbulent boundary layer in the portion of the inner wall surface 55 provided with the plurality of depressions 82A, and the turbulent flow in the turbulent boundary layer It is presumed that the separation point that separates when passing through the curved surface portion 55C of the inner wall surface 55 gradually moves and shifts to the downstream side of the air flow due to the diffusibility of air due to the generation. For reference, in FIG. 19a, assuming an inner wall surface 55 without a recess 82A, when the air traveling in the vicinity of the inner wall surface 55 flows (after peeling from the curved surface portion 55C of the inner wall surface 55), The flow direction of the air flowing in the state closest to the curved surface portion 55c of the inner wall surface 55 is indicated by a two-dot chain line arrow.

  Subsequently, the air (E1a, E1b) flowing so as to move to the first bending passage portion 54B of the air duct 51D is a blocking member 64 of the most upstream suppressing portion 61 present at the upstream end of the first bending passage portion 54B. On the other hand, after finally passing through the gap 63 of the most upstream restricting portion 61 and flowing into the passage space 54a of the first bending passage portion 54B, it is almost directed downward from the first bending passage portion 54B. It moves to the passage space 54a of the second bending passage portion 54C that is bent in the direction perpendicular to the direction (see FIG. 12). At this time, the air (E2b) flowing in contact (approaching) the inner inner wall surface (bottom surface portion) 56 between the first bending passage portion 54B and the second bending passage portion 54C is shown in FIG. 19b (FIG. 13b). As shown in FIG. 5), when passing through a plurality of depressions 82B provided in the entire area of the flat surface portion 56F and the entire area of the curved surface portion 56C on the inner wall surface 56, each part of the air is illustrated by a dotted arrow. The turbulent flow spirals so as to enter the recessed space downstream (downstream) of the protrusion 81B, and proceeds while bending so as to approach the curved surface portion 56C (see the progress state of the solid arrow).

  This is because the portion of the air (E2b) flowing in contact with (approaching) the inner wall surface 56 becomes a turbulent boundary layer in the portion of the inner wall surface 56 provided with the plurality of depressions 82B, and the turbulent flow in the turbulent boundary layer It is assumed that the separation point that separates when passing through the curved surface portion 56C of the inner wall surface 56 gradually moves and shifts to the downstream side of the air flow due to the diffusibility of air due to the generation. In FIG. 19b, for the sake of reference, assuming an inner wall surface 56 that is not provided with a recess 82B, when the air traveling in the vicinity of the inner wall surface 56 flows (after peeling from the curved surface portion 56C of the inner wall surface 56). The flow direction of the air flowing in the state closest to the curved surface portion 56c of the inner wall surface 56 is indicated by a two-dot chain line arrow.

  Further, in the case of this air duct 51D, by providing a plurality of depressions 82A and 82B on both of the inner wall surfaces 55 and 56, the air finally discharged from the outlet 53 is the longitudinal direction of the outlet 53. In (B), the wind speed at the end portion 53a close to the inlet 52 (which also becomes the end portion close to the inner wall surface 55) becomes relatively weak with respect to the wind speed at other portions, and the outlet 53 The wind speed at the end 53c on the pre-position side, which is closer to the inlet 52 in the short direction C, is reduced relative to the wind speed at the end on the opposite post-position side. This effect can be similarly obtained even when the wind speed of the air discharged from the outlet 53 is increased.

  As a result, the air discharged from the outlet 53 of the air duct 51D is discharged in a state where both the uneven wind speed in the entire longitudinal direction of the outlet 53 and the uneven wind speed in the entire short direction are further reduced. Incidentally, in this air duct 51D, even if the wind speed of the air discharged from the outlet 53 is increased, the longitudinal direction of the outlet 53 is not changed without changing the shape or structure of the passage space 54a of the passage portion 54. It is possible to discharge in a state in which the unevenness of the wind speed and the unevenness of the wind speed in the short direction are reduced.

[Other embodiments]
In the first embodiment, each of the bending directions 54B and 54C in which the passage space 54a is bent in one direction (J1 and J2) as the inner wall surfaces 55 and 56 provided with the plurality of protrusions 81 or the depressions 82, J1 and J1. Although the case where at least a part of each inner wall surface (55, 56) respectively existing inside J2 is applied has been illustrated, the plurality of protrusions 81 or the depressions 82 may be, for example, an inner one as exemplified below. It is also effective to provide it on the wall surface.

  That is, as shown in FIG. 20, the inner wall surface on which the plurality of protrusions 81 or the depressions 82 are provided has an air duct 51E having an extended bent passage portion 54K in which the passage space 54a bends in a plurality of directions (two in this example). Then, at least one of the curved surface portion (57C, 58C) and the flat surface portion (57F, 58F) of each inner wall surface (57, 58) existing inside each bending direction (J3, J4) in the bending passage portion 54K. Part. The curved surface portions (57C, 58C) in this case are bent curved surface portions, and since there are only a few portions that are actually curved surfaces, a range including a small portion of the plane portion existing before and after the curved surface portion is defined as the curved surface portion. Further, the inner wall surface on which the plurality of protrusions 81 or the depressions 82 are provided is not limited to one having a curved surface portion of a cylindrical curved surface, for example, but bends while being curved in a curved shape or bent in a plurality of stages. It may include a polygonal curved surface portion.

  Further, with regard to the plurality of protrusions 81 or the depressions 82, the first embodiment has shown a configuration example in which protrusions and grooves extending linearly in a direction substantially perpendicular to the air flow direction are provided with a predetermined interval. However, it is not limited to this, For example, you may comprise so that it may illustrate next.

  That is, as the plurality of protrusions 81 or depressions 82 formed of linearly extending ridges and grooves, the air flows as much as possible along the curved surface portion of the corresponding inner wall surface as it becomes downstream in the air flow direction. From the point of view, the projecting height h (or depth d), width w, interval p, etc. may be provided under gradually changing conditions as the air flows in the downstream direction. Further, a plurality of protrusions 81 and a plurality of depressions 82 may be provided in combination between corresponding inner wall surfaces or between a curved surface portion and a flat surface portion of the inner wall surface. Further, the plurality of protrusions 81 or the recesses 82 are not limited to those formed of linearly extending ridges or grooves, for example, those formed of ridges or grooves extending in a curved shape, or of the corresponding inner wall surface It may have a shape that is scattered on the curved surface portion and the flat surface portion, or a shape that extends in a direction that intersects the direction in which air flows (excluding the orthogonal direction).

  Moreover, you may provide 3 or more as a suppression part in the ventilation duct 51 (51D, 51E). In addition, the suppression unit includes the most downstream suppression unit, and any part of the passage space 54a of the passage portion 54 of the air duct 51 whose cross-sectional shape is changed or the direction in which air flows in the passage space 54a. It is preferable to provide in the site | part after changing (such as immediately after).

  For the most downstream restraint portion 62, for example, a breathable member 70 typified by a porous member such as a nonwoven fabric applied to a filter or the like (one in which the plurality of vent portions 71 are irregularly shaped through gaps) is used. It can also be configured.

  Furthermore, the thing of another shape is applicable as the air duct 51 (51B-51D). For example, air ducts 510A, 510B, and 510C illustrated in FIGS. 21a, 21b, and 21c may be applied as the air ducts having other shapes. Further, the air duct has a shape having three or more bending passage portions (including an extended bending passage portion) and can be applied.

  In addition, the charging device 4 to which the blowing device 5 is applied may be a charging device of a type in which the grid electrode 24 is not installed, 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. Further, the target structure to which the blower 5 is applied may be a corona discharger for discharging the photosensitive drum 21 or the like, a corona discharger for charging or discharging a charged body other than the photosensitive drum, and A long structure may be used as long as it is necessary to blow air other than the corona discharger.

  The image forming apparatus 1 is not particularly limited in the configuration of the image forming method and the like as long as the image forming apparatus 1 is equipped with a long target structure to which the air 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. If necessary, an image forming apparatus that forms an image made of a material other than the developer may be used.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 4 ... Charging apparatus (elongate target structure, corona discharger)
5 ... Blower 50 ... Blower 51, 51D, 51E, ... Blower duct (Blower pipe)
52 ... Inlet 53 ... Outlet 54 ... Passage portion 54a ... Passage space 54A ... Introduction passage portion 54B ... First bending passage portion (bending passage portion)
54C ... 2nd bending passage part (bending passage part)
55, 56, 57, 58 ... inner wall surfaces 55C, 56C, 57C, 58C ... curved surface portions 55F, 56F, 57F, 58F of inner wall surfaces ... flat surface portions 61 of inner wall surfaces ... most upstream restraint portions (at least of a plurality of restraint portions) One)
62 ... the most downstream restraint (the other one of the restraints)
63 ... Gap 70 ... Breathable member 71 ... Ventilation part 81 ... Protrusion 82 ... Depression B ... Longitudinal direction D ... Transverse direction E ... Air (flow)
R1 ... Direction in which air in the introduction passage should flow (constant direction)
J1 ... Bending direction (one direction)
J2, J3, J4 ... Bending direction (another direction)

Claims (9)

An inlet for taking in air;
It is arranged in a state facing a longitudinal portion of a long target structure to be blown by discharging air taken in from the inlet, and has a long opening shape parallel to the longitudinal portion of the target structure. And an outlet having an opening shape different from that of the inlet,
A passage portion in which a passage space for flowing air by connecting between the inlet and the outlet is formed in a shape bent at at least one place;
A plurality of restraining portions that are provided at different portions in the direction of flowing air in the passage space of the passage portion and suppress the flow of air;
As the bending passage portion, a first bending passage that is bent and extended in one direction different from the certain direction so that the passage cross-sectional area is enlarged from the middle of the introduction passage portion that allows air taken in from the inlet to flow in a certain direction. And a second bent passage portion that is bent and extended in one direction different from the one direction from the middle of the first bent passage portion,
At least one of the plurality of restraining portions blocks the passage space of the first bending passage portion in a state of crossing, and has an elongated gap extending in the transverse direction to prevent passage of air. It is provided as the most upstream restraint that enables
Among the passage portions , at least a part of the curved surface portion of the inner wall surface existing inside the bending direction between the first bending passage portion and the second bending passage portion, and a part of the plane portion existing immediately before the curved surface portion. And a plurality of protrusions or depressions.   A plurality of protrusions or depressions on at least a part of the curved surface portion of the inner wall surface present inside the bending direction between the introduction passage portion and the first bending passage portion and a part of the flat surface portion immediately before the curved surface portion. The blast tube according to claim 1, wherein A part of the curved surface part is a part existing on the upstream side of the curved surface part in the direction of air flow, and a part of the flat surface part is a part existing on the side near the curved surface part of the flat surface part. The blower pipe according to claim 1 or 2. One of the plurality of restraining portions other than the most upstream restraining portion is provided as a most downstream restraining portion that closes the outlet with a breathable member interspersed with a plurality of venting portions. Item 4. The blower tube according to any one of Items 1 to 3. The blower tube according to claim 1 , wherein the target structure is a corona discharger . A blower for sending air; and the blower pipe according to any one of claims 1 to 5,
Blower apparatus characterized by taking air sent from the blower from the inlet of the blower tube. The air blower according to claim 6, wherein the target structure is a corona discharger . A long target structure to be blown with air;
A blower that blows air toward a longitudinal portion of the target structure,
An image forming apparatus, wherein the blower is configured by the blower according to claim 6 . The image forming apparatus according to claim 8, wherein the target structure is a corona discharger .

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