JP5900396B2 - 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 duct (blower pipe) that guides the air sent from the blower to a target structure such as a corona discharger.

  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 orthogonal 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 that can reduce the wind speed of the air discharged from the outlet from being relatively weak particularly at the end near the inlet in the longitudinal direction of the outlet. The blower and the image forming apparatus used are provided.

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. An outlet having an opening shape different from that of the inlet;
A passage section formed in a shape in which a passage space for flowing air by connecting between the inlet and the outlet is 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;
The passage portion is formed in a shape extending in a direction parallel to the longitudinal direction of the outlet from the inlet, and a direction approaching the outlet at the downstream end of the introduction passage portion in the direction of flowing air. At least a first bent passage portion formed in a shape that is bent and connected to extend,
At least one of the plurality of restraining portions is cut off in a state where a part of the passage space is traversed in a passage space that is an upstream end of the first bending passage portion of the passage portion in the direction of flowing air. And it is provided as a most upstream restraint that allows passage of air by the presence of an elongated gap extending in the transverse direction,
A part of the air taken in from the inlet is transferred to the end of the gap from the inlet to the end of the gap from the inlet to the end near the inlet of the gap in the most upstream suppressing portion. A partition plate that forms a dedicated passage space that is allowed to flow and pass to the immediately preceding position is provided in a state where the height of the dedicated passage space is the same as the height of the gap. is there. Here, the above-mentioned same height is not limited to the case where the height is completely the same as the height of the gap, but includes the case where the height is a value that deviates from the height of the gap as long as the same effect is achieved. (The same applies to the subsequent steps.)

  The blast pipe of this invention (A2) is the blast pipe of the above invention A1, wherein the height of the dedicated passage space is less than or equal to twice the height of the end of the gap in the most upstream suppressing portion. That is the height.

  The blast pipe of this invention (A3) is the shortest side wall from the inlet of the introduction passage section to the upstream end in the direction of flowing air of the first bending passage section in the blast pipe of the invention A1 or A2. The surface portion is formed of a single curved surface or a curved surface that bends closer to the end of the gap.

  The blast pipe of this invention (A4) is the blast pipe of any one of the inventions A1 to A3, wherein one of the plurality of restraining parts other than the most upstream restraining part is provided with a plurality of ventilation parts. It is provided as the most downstream restraint portion that is closed by the scattered air-permeable members.

  The blast tube of this invention (A5) is the blast tube of any of the above inventions A1 to A4, wherein the target structure is a corona discharger.

  The blower of this invention (B1) includes a blower for sending air and the blower pipe according to any one of the inventions A1 to A4, and takes in air sent from the blower from an inlet of the blower pipe. It is what.

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

  According to the blower pipe of the invention A1, even when the wind speed of the air discharged from the outlet is increased, the wind speed of the air discharged from the outlet is particularly at the end near the inlet in the longitudinal direction of the outlet. Relatively weakening can be reduced.

  In the blast pipe of the invention A2, the wind speed of the air discharged from the outlet is higher than that in the case where the height of the dedicated passage space is higher than twice the height of the end of the gap in the most upstream suppressing portion. In particular, it is possible to reliably reduce the relative weakening at the end near the entrance in the longitudinal direction of the exit.

  In the blast pipe of the invention A3, the wind speed of the air discharged from the outlet is particularly close to the inlet in the longitudinal direction of the outlet as compared with the case where the side wall portion of the introduction passage portion is not formed by the one flat surface or curved surface. The relative weakening at the side end can be reliably reduced.

  In the blast pipe of the invention A4, air can be discharged in a state in which the unevenness of the wind speed in the longitudinal direction of the outlet is reduced as compared with the case where the most downstream suppressing portion is not provided at the outlet.

  In the blast tube of the invention A5, air with reduced wind speed unevenness in the longitudinal direction of the corona discharger can be blown against the corona discharger as compared to the case without the configuration of the invention.

  According to the blower of the invention B1, the air discharged from the outlet of the blower pipe is particularly close to the inlet in the longitudinal direction of the outlet even when the wind speed of the air discharged from the outlet is increased. It is reduced that the wind speed becomes relatively weak at the portion.

  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 by which the wind speed nonuniformity in the longitudinal direction of the corona discharger was reduced can be sprayed with respect to a corona discharger.

  According to the image forming apparatus of the invention C1, the air discharged from the outlet of the blower tube in the blower is particularly at the inlet in the longitudinal direction of the outlet even when the wind speed of the air discharged from the outlet is increased. It becomes possible to reduce the relative weakening of the wind speed at the end on the near side, and thereby the air exhausted from the outlet of the blow pipe is made to flow unevenly in the longitudinal direction of the target structure. It can be sprayed in a state where there is little.

  In the image forming apparatus according to the invention C2, it is possible to blow air with reduced wind speed unevenness in the longitudinal direction of 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 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 air blower of FIG. 3 is seen from upper direction. 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 structure of the ventilation pipe in the air blower of FIG. 3 is seen from upper direction. It is sectional explanatory drawing which follows the Q1-Q1 line | wire of the blast pipe of FIG. It is sectional explanatory drawing which follows the Q2-Q2 line | wire of the blast pipe of FIG. It is explanatory drawing which shows typically the direction and state which air flows in the ventilation pipe | tube of FIG. It is explanatory drawing which shows typically the direction and state which air flows in the ventilation pipe | tube of FIG. It is explanatory drawing which shows typically the direction and state which air flows in the ventilation pipe | tube of FIG. It is a graph which shows the result of the evaluation test which measured the wind speed state in the exit of the ventilation duct in the air blower which concerns on Embodiment 1. FIG. It is a graph which shows a result when analyzing the wind speed state in the exit of the ventilation duct in the air blower which concerns on Embodiment 1 by simulation. It is explanatory drawing which shows another example of a structure of the ventilation space for exclusive use formed with the clearance gap of the most upstream suppression part in a ventilation duct, and a partition plate. It is a schematic explanatory drawing which shows another structural example 1 of a ventilation duct. It is a schematic explanatory drawing which shows another structural example 2 of a ventilation duct. It is sectional drawing which follows the QQ line of the ventilation duct of FIG. It is a schematic explanatory drawing which shows another structural example 3 of a ventilation duct. It is explanatory drawing which showed typically the direction and state which the air flows in the ventilation duct of FIG. It is upper surface explanatory drawing which shows the various example of a ventilation duct. It is sectional drawing which shows typically the direction and state of the air flow in the ventilation duct of a structure which does not provide a partition plate, (a) shows the case of the conditions where the wind speed of the air discharged | emitted from an exit is comparatively low, (b ) Shows a case where the wind speed of the air discharged from the outlet is relatively high (increased). It is a graph which shows a result when the wind speed state in the exit of the ventilation duct shown in FIG. 22 is analyzed by simulation.

  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, and FIG. 2 shows a charging device that is used in the image forming apparatus and is an example of a long target structure to which air should be abutted by the blower tube or blower. 3 shows the outline of the blower pipe or blower, FIG. 4 shows the state of the cross section along the line Q-Q in the blower (blower pipe) of FIG. 3, and FIG. 5 shows the blower 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.

  As the blower 50, for example, a radiant flow type blower fan is used, and is driven and controlled so as to send a 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 is open at one end with an inlet 52 and closed at the other end, and is entirely linear along the longitudinal direction of the outlet 53 (longitudinal direction B of the charging device 4). In a substantially horizontal direction (a direction substantially parallel to the coordinate axis X) in a state where the width of the passage space is widened from a portion near the other end of the introduction passage portion 54A, a rectangular tube-shaped introduction passage portion 54A formed so as to extend A rectangular tube-shaped first bent passage portion 54B formed so as to be bent substantially at a right angle and a vertical direction (from the one end portion of the first bent passage portion 54B to the lower side while maintaining the same width of the passage space ( The second bending passage portion 54 </ b> C is formed to be bent in a direction substantially parallel to the coordinate axis Y and extend toward the charging device 4. 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.). 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 (FIGS. 3 and 4). A connection duct 55 is connected 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 (FIG. 3). 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 that expands only in the horizontal direction (regardless of the height) in the first bent passage portion 54B. In other words, the cross-sectional shape of the passage space 54a of the introduction passage portion 54A is the cross-sectional shape of the passage space 54a that is abruptly widened in the first bent passage portion 54B.

  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. In this way, the tendency of the air speed of the air exiting from the outlet to be ultimately non-uniform is that the direction in which the air flows (progress) in the air duct 51 changes regardless of whether or not the cross-sectional shape of the passage space 54a changes. That is, the same occurs when the passage space 54a is bent in the middle. 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 (side wall part which forms) of each duct. Incidentally, in the air ducts 510B and 510C, the air flow direction is changed in the middle (the passage space 54a is bent in the middle) and at least one of the cross-sectional shape and the cross-sectional area of the passage space is changed. It is also a configuration example. 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.

  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. A passage portion 54 formed in a bent shape at a location), and the inlet 52 is formed outside the end portion 53a on the side close to the inlet 52 in the longitudinal direction (B) of the outlet 53. On the premise that the air duct is present, two suppression portions 61 and 62 that suppress the flow of air are provided at different portions in the flow direction of the passage space 54a of the passage portion 54. Here, the air duct 510A having a configuration in which the passage portion is not bent as illustrated in FIG. 21a is not included in the category of the air duct of the air blower 5 in the present invention.

  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. 4 and the like, the blocking member 64 blocks the first bent path portion 54B in a state of crossing the upper portion of the cross-sectional shape in the passage space 54a, 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 FIGS. 4 and 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 FIG. 6, 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 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 research by the present inventors, in the blower 5, the wind speed (air volume) of the air discharged from the outlet 53 of the blower duct 51 (the blower duct 510 having a configuration in which the partition plate 80 described later is not provided). Is used under relatively few conditions, as shown in FIG. 22a by a two-dot chain line with an arrow, the low-velocity state introduced from the inlet 52 into the introduction passage portion 54A. The air (Ea) passes in a state of being close to the end portion 63a near the inlet 52 in the gap 63 of the most upstream suppressing portion 61, and finally the end portion 53a near the inlet 52 of the outlet 53. It has been confirmed that it is possible to suppress to some extent the reduction of the wind speed of the air when discharged from the air compared with the wind speed of the air discharged from the other outlet portions.

  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 has moved away from the end portion 63a on the side close to the inlet 52 in the gap 63 of the most upstream suppressing portion 61. The air velocity at the time of passing through the state and finally being discharged from the end portion 53a near the inlet 52 of the outlet 53 may be reduced as compared with the air velocity of air discharged from the other outlet portions. It has been confirmed. 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 2 m / second or more, for example.

  Therefore, in the blower duct 51 in the blower 5, as shown in FIGS. 7 to 9 and the like, the end of the introduction passage portion 54 </ b> A on the side close to the inlet 52 of the gap 63 in the most upstream suppressing portion 61 from the inlet 52. A partition plate 80 that forms a dedicated passage space 54b through which a part of the air taken in from the inlet 52 flows to the position just before the end portion 63a of the gap is provided in the specific portion 54Ae that reaches the portion 63a.

  The partition plate 80 is provided in a state (h = H) in which the height h of the dedicated passage space 54b is the same height as the height H of the gap 63 in the most upstream suppressing portion 61. Here, it is assumed that the height h of the dedicated passage space 54b and the height H of the gap 63 are set to the same size in the entire area. Further, the partition plate 80 is thin enough to prevent the air flow in the introduction passage portion 54A from being unnecessarily disturbed on the assumption that the dedicated passage space 54a can be formed in the passage space of the introduction passage portion 54A. It is the flat plate-shaped board | plate material which consists of. The thickness d is, for example, 1 mm or less. Furthermore, the partition plate 80 is disposed in a state substantially parallel to the bottom surface of the inner wall of the introduction passage portion 54A. Further, in the partition plate 80, the downstream end 80e in the direction R1 in which the air in the introduction passage portion 54A should flow passes through the end 63a of the gap with respect to the transverse direction D of the blocking member 64 in the most upstream suppressing portion 61. It arrange | positions in the state which substantially corresponds with an orthogonal line.

  The passage space in the specific portion 54Ae of the introduction passage portion 54A is provided with the partition plate 80, thereby providing a normal passage space 54a existing on the upper surface side of the partition plate 80 as shown in FIGS. And a dedicated passage space 54 b existing on the lower surface side of the partition plate 80. Further, the passage space in the remaining portion other than the specific portion 54Ae of the introduction passage portion 54A is a single passage space 54a in which the dedicated passage space 54b does not exist because the partition plate 80 is not provided. Reference numeral 63b in FIGS. 7 and 8 indicates an end of the gap 63 far from the inlet 52 (an end opposite to the end 63a).

  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. 5, 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.

  The air (E) taken in from the inlet 52 of the air duct 51 proceeds so as to flow in a state along the direction R1 in which the air should flow in the passage space of the introduction passage portion 54A, as shown in FIGS. The specific portion 54Ae of the introduction passage portion 54A flows in a state (air E1a, E1b) that is divided into a normal passage space 54a partitioned by the partition plate 80 and a dedicated passage space 54b. At this time, the air (E) taken in from the inlet 52 flows into the normal passage space 54a and the dedicated passage space 54b without disturbing the flow (state) due to the presence of the partition plate 80. Proceed naturally divided into air E1b. Further, the air E1b flowing into the dedicated passage space 54b flows smoothly without pressure loss because the height h of the passage space 54b is constant.

  Subsequently, the air (E1a, E1b) that has passed through the specific portion 54Ae of the introduction passage portion 54A is one passage space of the introduction passage portion 54A in which the partition plate 80 no longer exists, as shown in FIGS. After flowing so as to merge in 54a, it flows so as to move from the middle of 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 at the end portion. Further, the air (E1a, E1b) flowing so as to move to the first bending passage portion 54B is blocked by the blocking member 64 of the most upstream suppressing portion 61 existing at the upstream end portion of the first bending passage portion 54B. On the other hand, it finally flows through the gap 63 of the most upstream suppressing portion 61.

  At this time, a part of the air (E1b) that has passed through the dedicated passage space 54b of the introduction passage portion 54A escapes from the dedicated passage space 54b to the large passage space 54a as shown in FIG. When moving, it diffuses and the straightness is relaxed, so that in the gap 63 of the most upstream suppressing portion 61 (existing immediately after passing through the dedicated passage space 54b), the end 63a on the side close to the inlet 52 is placed. It begins to flow in a close state. In addition, air that passes through a position close to the side wall surface portion 54As constituted by one plane (inner wall surface) out of the air (E1b) that passes through the dedicated passage space 54b of the introduction passage portion 54A passes through the side wall surface portion 54As. It becomes easy to flow without being particularly obstructed toward one end portion 63a of the gap 63 of the most upstream suppressing portion 61 immediately after the downstream end portion in the air flow direction.

  And the air (E2) when flowing into the passage space 54a of the first bent passage portion 54B through the gap 63 of the most upstream restraining portion 61 is in a state where the flow is restrained by the most upstream restraining portion 61 ( The pressure increases), and flows into the gap 63 in a uniform state. 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).

  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.

  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. It passes through a plurality of ventilation portions (holes) 71 in the breathable member 70 to be configured and is blown out from the outlet 53 in a state (E3) in which the traveling direction is aligned (see the direction and length of the arrow E3 in FIG. 8). ).

  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.

  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). Even in the hand direction C (FIGS. 4, 6 and the like), they are almost aligned.

  Furthermore, the air finally discharged from the outlet 53 is an end on the side close to the inlet 52 in the longitudinal direction (B) of the outlet 53 by providing the partition plate 80 particularly in the specific portion 54Ae of the introduction passage portion 54A. It is possible to reduce the relative weakening of the wind speed at the portion 53a (portion substantially corresponding to the end portion 63a of the gap 63 in the most upstream suppressing portion 61). This effect can be similarly obtained even when the wind speed of the air discharged from the outlet 53 is increased as described above. Thereby, the air discharged from the outlet 53 is discharged in a state in which the unevenness of the wind speed in the entire longitudinal direction of the outlet 53 is further 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. Further, the blown air is discharged from the outlet 53 in a state in which the wind speed at the end 53a near the inlet 52 in the longitudinal direction B of the outlet 53 of the blower duct 51 is reduced relatively. The two discharge wires 41A and 41B and the region facing the outlet end 53a of the grid electrode 42 are also blown at a wind speed almost the same as the other regions.

  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.

  In the test, air with an air volume at which the average wind speed from the outlet 53 of the air duct 51 was about 1.0 m / sec was introduced from the blower 50, and the wind speed in the longitudinal direction (B) of the outlet 53 at that time was measured. The measurement is performed using an anemometer (F900, manufactured by Cambridge Accusens). As shown in FIG. 12, the 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 its position This was done by moving the anemometer in the longitudinal direction B at two locations, the end position P2 (post position) located downstream in the rotation direction A. The results of this test are shown in FIG.

The entire shape of the air duct 51 is as shown in FIGS. 3 to 9, 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. The one having an opening shape was used. 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. The length H is a dimension that is inclined within the range of 1 to 2 mm, the path length M is 8 mm, and the width W is 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 ). It was configured using.

  Further, the inlet 52 (one end where the inlet 52 of the introduction passage portion 54A exists) has a shape protruding by a dimension G of about 50 mm outward from one end 53a of the outlet 53 (FIG. 7). Further, the partition plate 80 uses a flat plate having a thickness of about 1 mm, and the height h of the dedicated passage space 54b is about 1.5 mm (average of the height H of the gap 63) in the specific portion 54Ae of the introduction passage portion 54A. It was arranged so as to be a value about 1 times the value).

  As shown in FIG. 13, the wind speed in the longitudinal direction (B) of the outlet 53 of the air duct 51 became a value close to about 1.0 m / sec, which is the average wind speed of the target value over almost the entire area in the longitudinal direction. . Further, the results of the wind speeds at the pre-position P1 and the post-position P2 of the outlet 53 are almost the same value in the longitudinal direction (B) of the outlet 53, and thus the wind speed in the short direction C of the outlet 53 is also It can be seen that they are almost aligned.

<Analysis>
Next, analysis by computer simulation performed using the air duct 51 of the air blower 5 will be described.

  By performing an analysis by computer simulation based on the air duct 51 used in the test, air having an increased air volume is discharged from the outlet 53 of the air duct 51 so that the average wind speed is at least about 2 m / second or more. When it was necessary to make it, the wind speed distribution of the air (E3) actually blown out from the outlet 53 was examined. The wind speed calculated at this time is the distribution result when all the components of the air blown out in various other directions are added to the components of the air blown down from the outlet 53 (the direction opposite to the coordinate axis Y). The results obtained from this analysis are shown in FIG.

  From the results shown in FIG. 14, the wind speed in the longitudinal direction (B) of the outlet 53 of the air duct 51 is about 25 mm at a point where the wind speed starts to become 2 m / sec or more at the end 53 a near the inlet 52 of the outlet 53. It is reduced that the wind speed at the one end 53a of the outlet is relatively weak (result of a comparative example described later: see FIG. 23 for comparison). Note that the wind speed at a position of 170 to 300 mm in the longitudinal direction of the outlet 53 slightly fluctuates. This is, for example, a formally influenced by the sampling of analysis values. It is a small uneven wind speed that does not cause any problems.

<Comparative example>
FIG. 23 assumes a blower duct (comparative example; blower duct 510 shown in FIG. 22) having a configuration in which the partition plate 80 of the blower duct 51 used in the above test is not disposed, and is based on the blower duct 510 of the comparative example. As in the case of the above analysis, the result when an analysis by computer simulation is performed is shown.

  As is clear from the results of FIG. 23, in the air duct 510 of the comparative example, the wind speed in the longitudinal direction (B) of the outlet 53 is 2 m / sec or more at the end 53a on the side close to the inlet 52 of the outlet 53. The point at which the point begins to become is a position of about 32 mm, and the wind speed at the end 53a of the outlet 53 near the inlet 52 is relatively reduced as compared with the other parts.

[Other embodiments]
In the first embodiment, the configuration example in which the height H of the gap 63 in the most upstream suppressing portion 61 as the blower duct 51 is a constant value in the entire region (transverse direction D) is shown. For example, FIG. As shown in FIG. 4, the height H of the gap 63 in the most upstream restraining portion 61 is different from the height Ha of the end 63a near the inlet 52 and the height Hb of the end 63b far from the inlet 52 ( In the case of the air duct 51 set to Ha <Hb), the partition plate 80 in the air duct 51 may be provided under the following conditions.

  In other words, the partition plate 80 at this time is arranged so that the height h of the dedicated passage space 54b is not more than twice the height Ha of the end 63a of the gap in the most restricting portion 61. To do. When the partition plate 80 is disposed in a state in which the height h of the dedicated passage space 54b exceeds twice the height Ha of the end 63a of the gap, the air (E1b) that has passed through the dedicated passage space 54b. ) Is diffused toward the end 63a of the gap, and the effect of proceeding is difficult to obtain. Incidentally, the gap 63 shown in FIG. 15 is in a state of gradually increasing as the height h moves from the end portion 63a to the end portion 63b (a height that changes so as to be inclined).

  Further, the partition plate 80 in the air duct 51 has a side where the height h of the dedicated passage space 54b is close to the inlet 52, regardless of whether the height of the end 63a of the gap is constant or gradually increased. It may be arranged such that the height ha at the end and the height hb at the end far from the inlet 52 have different values. In this case, with respect to the height h of the dedicated passage space 54b, the height ha at the end near the entrance 52 is higher than the height hb at the end far from the entrance 52 (ha>). hb) is preferably set. The height h of the dedicated passage space 54b may be handled by the average value of the heights ha and hb at each end thereof. In addition, the height difference (ha−hb) of the height h of the dedicated passage space 54b at this time is smaller as the pressure loss of the air E1b passing through the dedicated passage space 54b does not occur. desirable.

  As the air duct 51, for example, as shown in FIG. 16, the shortest side wall surface portion (of which is from the inlet 52 of the introduction passage portion 54A to the upstream end portion of the first bending passage portion 54B in the direction R2 in which the air flows) A blower duct 51B having a side wall surface part 54Ar whose wall surface is formed by one curved surface may be applied. That is, the side wall surface portion 54As (the inner wall surface thereof) is formed as one continuous curved surface (curved surface) that bends from the inner end portion 52a of the inlet 52 toward the end portion 63a of the gap.

  In the air duct 51B, air passing through a position close to the side wall surface portion 54Ar configured by one curved surface (inner wall surface) out of the air (E1b) passing through the dedicated passage space 54b of the introduction passage portion 54A. The side wall surface portion 54Ar becomes easy to flow without being blocked particularly toward the one end portion 63a of the gap 63 of the most upstream suppressing portion 61 immediately after the downstream end portion in the air flow direction. It diffuses after passing through the passage space 54b and flows easily in the state of approaching the end 63a of the gap 63 in the most upstream restraint 61.

  Moreover, as the air duct 51, for example, as shown in FIG. 17 and FIG. 18, the blocking member 64 in the most upstream suppressing portion 61 is disposed at its upstream end (substantially the same portion as the virtual straight line VL: FIG. 7). However, the position is not substantially shifted from the inner end 52a of the inlet 52 to the downstream side in the direction R2 in which the air in the first bending passage portion 54B should flow (the upstream end in the direction R2 in which the air in the first bending passage portion 54B should flow). The air duct 51C which is arranged in a state existing in the (part) may be applied. Also in the air duct 51C, a partition plate 80 that forms a dedicated passage space 54b is provided in the specific portion 54Ae of the introduction passage portion 54A.

  In this air duct 51C, the air (E1b) passing through the dedicated passage space 54b formed by the partition plate 80 in the introduction passage portion 54A diffuses after passing through the passage space 54b, and is the most upstream suppression portion. It becomes easy to flow in the state which approached the one end part 63a of the clearance gap 63 in 61. FIG.

  Furthermore, as shown in FIG. 19, as the air duct 51, the first bent passage portion 54D and the second bent passage portion 54E having different configurations from the first bent passage portion 54B and the second bent passage portion 54C in the first embodiment. Alternatively, an air duct 51D having a third suppressing portion 65 may be applied. This air duct 51D has the same configuration as the air duct 51 according to Embodiment 1 except for the above-described changes.

  In other words, the first bent passage portion 54D in the air duct 51D is changed in such a shape that the height of the portion on the downstream side in the flow direction of the air in the passage space 54a gradually decreases as it becomes the downstream side. Yes. In addition, the second bent passage portion 54E in the air duct 51D extends from the lower portion, which is an approximately middle point in the direction in which the air flows in the first bent passage portion 54D, to the downward direction with the same width of the passage space. It is formed in a state where it is bent and extends so as to approach the charging device 4, and the end portion of the passage portion 54E has an opening shape (rectangular shape) substantially the same as the cross-sectional shape of the passage space 54a of the end portion. It is changed in that the outlet 53 is formed.

  Moreover, the 3rd suppression part 65 in ventilation duct 51D is a site | part located between the 1st suppression part 61 and the most downstream suppression part 62 in the direction which flows the air of the passage space 54a, specifically ,. The second bending passage portion 54E is provided at a portion on the upstream side in the flow direction of the air in the passage space 54a. Further, the restraining portion 65 is configured to have a gap 66 having a shape extending in a direction parallel to the longitudinal direction (B) of the opening shape of the outlet 53.

  The suppressing portion 65 is changed to a shape that narrows the outer shape of the second bending passage portion 54E, and has a shape in which a narrow gap (narrow passage) 66 exists in a substantially central portion of the passage space 54a of the passage portion 54E. It is configured by forming. In addition, the height H, the path length M, and the width W of the gap 66 flow from the first bent path portion 54D to the second bent path portion 54E in substantially the same manner as in the case of the gap 63 in the first suppressing portion 61. It is selected and set from the viewpoint of making the air velocity as uniform as possible, and is set in consideration of the size (capacity) of the duct 51D and the flow rate per unit time of the air that should flow through the duct 51D or the charging device 4. The

  Also in the air duct 51D, a partition plate 80 that forms a dedicated passage space 54b is provided in the specific portion 54Ae of the introduction passage portion 54A. The configuration of partition plate 80 is substantially the same as the configuration of partition plate 80 in the first embodiment.

  The blower 5 (D) using the blower duct 51D operates as follows.

  First, as shown in FIG. 20, the air (E) sent from the blower 50 is taken in from the inlet 52 of the blower duct 51D, and the normal passage space 54a and the dedicated passage space 54b in the specific portion 564Ae of the introduction passage portion 54A. After being divided into two (arrows E1a, E1b), it is fed from the introduction passage portion 54A toward the first bending passage portion 54D. At this time, the air (E2) flowing into the first bending passage portion 54D passes through the gap 63 in the first suppressing portion 61, and thereby flows into the first bending passage portion 54B in the first embodiment (E2). ) In substantially the same state.

  Subsequently, the air (E2) flowing into the second bending passage portion 54D passes through the gap 66 in the third suppression portion 65 provided in the second bending passage portion 54E, and is in the passage space 54a of the passage portion 54E. (Refer to the direction of arrow E4 in FIG. 17 and the like). At this time, the air (E4) that flows through the gap 66 of the suppressing portion 65 and flows into the second bending passage portion 54E is suppressed by the suppressing portion 65 (the pressure increases), and the gap 66 flows in a uniform state. Moreover, the air (E4) flowing into the passage space 54a of the second bent passage portion 54E is more oriented in a direction in which the direction when flowing out from the gap 66 of the suppressing portion 65 is substantially perpendicular to the longitudinal direction (B) of the outlet 53. It is surely aligned. Further, the air (E4) flowing into the passage space 54a of the second bending passage portion 54E is a passage space of the second bending passage portion 54E having a larger volume than the passage space 54a of the first bending passage portion 54D and the space of the gap 66. It stays in 54a and the nonuniformity of the wind speed is further reduced.

  Finally, as shown in FIG. 02, the air (E4) that has flown into and stayed in the second bending passage portion 54E is located at the end of the second bending passage portion 54E (a little upstream in the direction of flowing air from the outlet 53). 20 through a plurality of ventilation portions (holes) 71 in the air-permeable member 70 constituting the most downstream restraint portion 62 provided in the portion) and blown out from the outlet 53 (the direction and length of the arrow E5 in FIG. 20, etc.) See). At this time, the air (E5) 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. Sent out. In addition, the air (E5) 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. It is sent out from the outlet 53 in a uniform state corresponding to the surface. Further, the air (E3) blown out from the outlet 53 is sent out along a direction substantially orthogonal to the longitudinal direction of the outlet 53.

  As described above, all of the air (E5) exiting from the plurality of ventilation portions 71 of the breathable member 70 is sent with the traveling direction thereof being substantially perpendicular to the longitudinal direction of the outlet 53, and the wind speed is substantially uniform. It becomes a state. Further, the wind speed of the air (E3) exiting from the outlet 53 is substantially uniform in the longitudinal direction (B) of the opening shape (rectangle) of the outlet 53, and is also substantially uniform in the short direction C. become.

  Furthermore, the air finally discharged from the outlet 53 is an end on the side close to the inlet 52 in the longitudinal direction (B) of the outlet 53 by providing the partition plate 80 particularly in the specific portion 54Ae of the introduction passage portion 54A. It is possible to reduce the relative weakening of the wind speed at the portion 53a (portion substantially corresponding to the end portion 63a of the gap 63 in the most upstream suppressing portion 61). This effect can be similarly obtained even when the wind speed of the air discharged from the outlet 53 is increased as described above. Thereby, the air discharged from the outlet 53 is discharged in a state in which the unevenness of the wind speed in the entire longitudinal direction of the outlet 53 is further reduced.

  Moreover, you may provide 4 or more as a suppression part in the ventilation duct 51 (51B-51D). 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 510B and 510C illustrated in FIGS. 21b and 21c may be applied as the air ducts having other shapes.

  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, 51B, 51C, 51D ... Blower duct (Blower pipe)
52 ... Inlet 53 ... Outlet 54 ... Passage portion 54a ... (Normal) passage space 54b ... Dedicated passage space 54A ... Introduction passage portion 54Ae ... Specific portion of the introduction passage portion (in the introduction passage portion, the most upstream restraint portion from the inlet) To the end of the gap near the entrance)
54 As ... Side wall surface portion 54 Ar made of one plane ... Side wall surface portion 54 B made of one curved surface ... First bending passage portion 54 C ... Second bending passage portion 61 ... Most upstream restraint portion (at least one of a plurality of restraint portions)
62 ... the most downstream restraint (the other one of the restraints)
63: Gap 63a: End near the inlet of the gap (end near the inlet of the most upstream suppression part)
70 ... Breathable member 71 ... Ventilation part 80 ... Partition plate B ... Longitudinal direction D ... Transverse direction E ... Air (flow)
R1 ... direction in which the air in the introduction passage portion should flow R2 ... direction in which the air in the first bending passage portion should flow h ... height H of the dedicated passage space ... height of the gap

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. An outlet having an opening shape different from that of the inlet;
A passage section formed in a shape in which a passage space for flowing air by connecting between the inlet and the outlet is 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;
The passage portion is formed in a shape extending in a direction parallel to the longitudinal direction of the outlet from the inlet, and a direction approaching the outlet at the downstream end of the introduction passage portion in the direction of flowing air. At least a first bent passage portion formed in a shape that is bent and connected to extend,
At least one of the plurality of restraining portions is cut off in a state where a part of the passage space is traversed in a passage space that is an upstream end of the first bending passage portion of the passage portion in the direction of flowing air. And it is provided as a most upstream restraint that allows passage of air by the presence of an elongated gap extending in the transverse direction,
A part of the air taken in from the inlet is transferred to the end of the gap from the inlet to the end of the gap from the inlet to the end near the inlet of the gap in the most upstream suppressing portion. A blower pipe characterized in that a partition plate that forms a dedicated passage space that is allowed to flow to the immediately preceding position is provided in a state in which the height of the dedicated passage space is the same as the height of the gap. .   2. The air duct according to claim 1, wherein a height of the dedicated passage space is a height equal to or less than twice a height of an end portion of the gap in the most upstream suppressing portion.   The shortest side wall surface portion extending from the inlet of the introduction passage portion to the upstream end portion in the direction in which the air flows in the first bending passage portion is formed as a single curved surface or a curved surface that curves to the side approaching the end portion of the gap. The blast 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 4,
The blower characterized by taking in the air sent from the said blower from the inlet_port | entrance of the said blower pipe.   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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