Image forming apparatus

Abstract

To prevent accumulation of discharge products and attachment of discharge products outside a discharge area.SOLUTION: An image forming apparatus comprises: a photoreceptor; an electrifier that has a discharge wire provided stretched in a rotation axis direction of the photoreceptor, and electrifies a surface of the photoreceptor at a predetermined electrical potential; a cleaning member that is provided movably in the rotation axis direction, and cleans the discharge wire; and a duct that is provided opposite to the discharge wire, has an opening provided extending in the rotation axis direction, and guides outside air to the discharge wire through the opening. The duct has a wind direction switching member that is provided at at least one portion of the duct, and is movable to a first position where it forms a first air channel opposite to a first area of the discharge wire, and a second position where it forms a second air channel opposite to a second area that is on the outside in the rotation axis direction of the first area of the discharge wire. The wind direction switching member is moved from the first position to the second position along with a movement of the cleaning member moving in the rotation axis direction from a standby position where it is retreated to the outside from the first area.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to an image forming apparatus having a duct.

Background Art

[0002] When forming an image with an electrophotographic image forming apparatus, first, a photoreceptor uniformly charged on the surface by a charging unit is exposed according to image data to form an electrostatic latent image. Next, a toner image is formed by attaching toner to the electrostatic latent image with a developing device. Then, the toner image is transferred to a sheet and fixed to form an image.

[0003] Here, as the charging unit, a configuration using corona discharge such as a corotron or a scorotron is known. When charging the photoreceptor by corona discharge, there is a risk that discharge products generated by the corona discharge adhere to the charging unit, causing charging failure.

[0004] On the other hand, in order to remove the above-described discharge products, a configuration has been proposed in which air outside the image forming apparatus is sent into the charging unit using a fan and a duct (Patent Document 1). Patent Document 1 describes a configuration in which a plurality of flow dividing plates are provided inside the duct in order to equalize the air discharged from the duct in the discharge region of the charging unit.

[0005] In recent years, with the demand for high speed and high image quality in image forming apparatuses used for commercial printing and the like, further uniformity of the wind speed with respect to the discharge region of the charging unit is required, while an increase in the air volume accompanying an increase in the ozone generation amount is also required. Patent Document 2 describes a configuration in which the air volume at the end of the charging operation is increased compared to when the charging operation is being performed in order to perform ventilation more efficiently.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

[0007] However, in the above prior art, there is a risk that discharge products may stay outside the discharge region and the stayed discharge products may adhere to the end portion of the image carrier located outside the discharge region. In this case, there is a risk of causing surface deterioration or chipping of the end portion of the image carrier to which the discharge products adhere.

[0008] Therefore, an object of the present invention is to suppress the stay of discharge products and the adhesion of discharge products outside the discharge region. MEANS FOR SOLVING THE PROBLEMS

[0009] A typical configuration of the present invention includes a photoreceptor, a charger having a discharge wire stretched in the direction of the rotation axis of the photoreceptor for charging the surface of the photoreceptor to a predetermined potential, a cleaning member movably provided in the direction of the rotation axis for cleaning the discharge wire, and a duct provided opposite to the discharge wire and having an opening extending in the direction of the rotation axis for guiding external air to the discharge wire through the opening. The duct has a wind direction switching member provided at at least one location of the duct and movable between a first position forming a first air passage facing a first region of the discharge wire and a second position forming a second air passage facing a second region outside the first region of the discharge wire in the direction of the rotation axis. The wind direction switching member is moved from the first position to the second position in accordance with the movement of the cleaning member in the direction of the rotation axis from a standby position where the cleaning member has retreated outside the first region. EFFECTS OF THE INVENTION

[0010] According to the present invention, it is possible to suppress the stay of discharge products and the adhesion of discharge products outside the discharge region. BRIEF DESCRIPTION OF THE DRAWINGS

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be exemplarily described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the following examples are not intended to limit the scope of the present invention only to those, unless otherwise specifically described.

[0013] 〔Example 1〕 (Image Forming Apparatus) The image forming apparatus according to Example 1 will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing the image forming apparatus according to Example 1.

[0014] The image forming apparatus A is an intermediate tandem type image forming apparatus that forms an image on a sheet by transferring toner of four colors, yellow (Y), magenta (M), cyan (C), and black (K), onto an intermediate transfer belt and then transferring the image onto the sheet. In the following description, although suffixes Y, M, C, and K are attached to the members that use the toner of each color, the configurations and operations of the respective members are substantially the same except for the color of the toner used. Therefore, the suffixes are appropriately omitted unless distinction is required.

[0015] As shown in FIG. 1, the image forming apparatus A includes an image forming unit 10 that forms a toner image and transfers it onto a sheet. The image forming unit 10 includes a photosensitive drum 1 (1Y, 1M, 1C, 1K) as a photoreceptor, a charging unit 2 (2Y, 2M, 2C, 2K), a laser scanner unit 3, and developing devices 4 (4Y, 4M, 4C, 4K). The image forming unit 10 also includes a primary transfer roller 5 (5Y, 5M, 5C, 5K), an intermediate transfer belt 6, a secondary transfer roller 9, and a secondary transfer opposing roller 8.

[0016] Above the image forming unit 10, a reader 20 for reading an image of a document is provided. The reader 20 has a document table glass 21 and a scanner unit 22. The scanner unit 22 optically reads an image of a document placed on the document table glass 21.

[0017] Next, the image forming operation of the image forming apparatus A will be described. First, when an image forming job signal is input to a control unit (not shown), a sheet S loaded and stored in a sheet cassette 11 is conveyed to a registration roller 16 by a feed roller 12, conveyance rollers 13, 14, and 15. The registration roller 16 conveys the sheet S to a secondary transfer portion formed by the secondary transfer roller 9 and the secondary transfer opposing roller 8 at a predetermined timing.

[0018] On one hand, in the image forming unit 10, first, the surface of the photosensitive drum 1Y is uniformly charged by the charging unit 2Y. Then, according to the image data of the document read by the reader 20, the laser scanner unit 3 irradiates the surface of the photosensitive drum 1Y with laser light to form an electrostatic latent image on the surface of the photosensitive drum 1Y. Next, the developing device 4Y attaches yellow toner to the electrostatic latent image formed on the surface of the photosensitive drum 1Y to form a yellow toner image on the surface of the photosensitive drum 1Y. The toner image formed on the surface of the photosensitive drum 1Y is primarily transferred to the intermediate transfer belt 6 by applying a voltage to the primary transfer roller 5Y.

[0019] By the same process, the surfaces of the photosensitive drums 1M, 1C, and 1K are also irradiated with laser light according to the image data from the laser scanner unit 3, and magenta, cyan, and black toner images are formed. Then, by applying a voltage to the primary transfer rollers 5M, 5C, and 5K, these toner images are superposed and transferred onto the yellow toner image on the intermediate transfer belt 6. Thereby, a full-color toner image is formed on the surface of the intermediate transfer belt 6.

[0020] After that, as the intermediate transfer belt 6 rotates and moves, the full-color toner image is sent to the secondary transfer unit. And by applying a voltage to the secondary transfer roller 9 in the secondary transfer unit, the full-color toner image on the intermediate transfer belt 6 is transferred to the sheet S.

[0021] Next, the sheet S onto which the toner image has been transferred is subjected to heating and pressure treatment in the fixing device 17, whereby the toner image on the sheet S is fixed to the sheet S. After that, the sheet S onto which the toner image has been fixed is discharged to the discharge tray 19 by the discharge roller 18.

[0022] (Charging Unit) Next, with reference to FIGS. 2 and 3, the configuration of the charging unit 2 will be described. FIG. 2 is a schematic perspective view of the charging unit 2 according to Embodiment 1. FIG. 3 is a schematic cross-sectional view of the charging unit 2 according to Embodiment 1.

[0023] The charging unit 2 is a charger that is provided to face the photosensitive drum 1 and charges the surface of the photosensitive drum 1 to a predetermined potential.

[0024] As shown in FIGS. 2 and 3, the charging unit 2 is composed of a front block 2a and a rear block 2b made of insulating members, a first shield plate 2c and a second shield plate 2d that define a charging region on the photosensitive drum 1, a grid plate 2e, and a charging wire 2f. The charging unit 2 forms a housing that surrounds the charging wire 2f with the front block 2a and the rear block 2b, and the first shield plate 2c and the second shield plate 2d. Openings are provided in the housing of the charging unit 2 on the side of the photosensitive drum 1 and the opposite side (the side of the duct 50). The duct 50, which will be described later, together with the first shield plate 2c and the second shield plate 2d that are shield members, forms an air passage (the first air passage 31 and the second air passage 32 shown in FIG. 7) that guides external air to the charging wire 2f.

[0025] The charging wire 2f, which is a discharge wire, is stretched in the axial direction of the rotation of the photosensitive drum 1 by a support member (not shown) between the front block 2a and the rear block 2b. The charging wire 2f is surrounded by the first shield plate 2c, the second shield plate 2d, and the grid plate 2e between the front block 2a and the rear block 2b, forming a discharge region 34 (the region shown by the dashed line in FIG. 3). During image formation, the charging wire 2f, the grid plate 2e, and the shield plates 2c and 2d receive a voltage from the contact portion of the rear block 2b.

[0026] When a voltage is applied to the charging wire 2f, the grid plate 2e, and the shield plates 2c and 2d, corona discharge occurs between the charging wire 2f and the grid plate 2e. The surface of the photosensitive drum 1 is charged by the ions generated by this corona discharge. The support member (not shown) is arranged outside the image formation region of the photosensitive drum 1 in the front-rear direction of the image forming apparatus A to prevent the charging of the photosensitive drum 1 from being hindered. In this embodiment, a voltage of approximately -10 kV is applied to the charging wire 2f, and voltages of approximately -1 kV are applied to the grid plate 2e and the shield plates 2c and 2d, respectively.

[0027] The charging unit 2 is configured to be detachable from a charging rail 35 attached to a frame (not shown) of the image forming apparatus A. On the upper surface of the charging rail 35, a duct 50 for sending air outside the image forming apparatus A into the charging unit 2 is provided. A fan 51 for generating an air flow for taking in air outside the image forming apparatus A into the duct 50 is attached to the duct 50. The duct 50 has a longitudinally long shape in the front-rear direction, and the fan 51 is disposed at the front end of the duct 50.

[0028] The duct 50 and the fan 51 are disposed above the charging unit 2 so as to avoid the laser scanner unit 3 (see FIG. 1) and other components of the image forming unit 10 above the image forming unit 10. The air supply port (inlet) of the duct 50 (fan 51) is provided on the front surface of the image forming apparatus A (see FIG. 1). The duct 50 forms a downwardly bent flow path in order to guide the air taken in from the front surface of the image forming apparatus A toward the charging unit 2.

[0029] Most of the duct 50 and the first shield plate 2c and the second shield plate 2d form an integral cavity. As shown by the arrow E in FIG. 3, the air taken into the duct 50 by the air flow generated by the fan 51 is guided by the duct 50, passes through the inside of the shield plates 2c and 2d of the charging unit 2, and is discharged to the outside of the charging unit 2. At this time, ozone and discharge products (such as ammonium nitrate generated by the combination of ozone with nitrogen and moisture in the air) generated by corona discharge around the charging wire 2f are discharged to the outside of the charging unit 2 together with the air.

[0030] In the rotational direction of the photosensitive drum 1, on the downstream side of the charging unit 2, an exhaust duct 70, which is a second duct for taking in the air discharged to the outside of the charging unit 2, is provided. In other words, the exhaust duct 70, which is the second duct, is provided on the downstream side of the duct 50, which is the first duct, in the rotational direction of the photosensitive drum 1. The air containing ozone and discharge products discharged to the outside of the charging unit 2 is sucked by the exhaust duct 70, passes through an ozone filter (not shown), and after the ozone and discharge products are removed, is exhausted to the outside of the image forming apparatus A. By removing ozone and discharge products from the charging unit 2 in this way, it is possible to suppress the occurrence of charging defects due to the attachment of discharge products to the charging wire 2f.

[0031] Note that the space (hollow portion) surrounded by the front block 2a, the rear block 2b, and the shield plates 2c and 2d has a function of guiding the air that has passed through the inside of the duct 50 to the discharge region 34 and the photosensitive drum 1, and further guiding it to the exhaust duct 70 through the shield opening 59 between the first shield plate 2c and the photosensitive drum 1. As described above, a support member (not shown) that supports the charging wire 2f needs to be disposed outside the image forming region of the photosensitive drum 1. Therefore, the length of the above-described space in the front-rear direction of the image forming apparatus A is 10% larger than the maximum image forming region 320 mm of the photosensitive drum 1, and is 350 mm in this embodiment.

[0032] (Cleaning member) In addition, as shown in FIG. 4, the image forming apparatus A has a cleaning member 36 for cleaning the charging wire 2f. The cleaning member 36 is held by a cleaning member holder 37 provided so as to be movable in the front-rear direction, and is provided in contact with the charging wire 2f. The cleaning member holder 37 reciprocates in the front-rear direction of the discharge region in response to the rotation of the lead screw 38. The cleaning member 36 reciprocates in the front-rear direction as the cleaning member holder 37 moves, and cleans the discharge region of the charging wire 2f. The cleaning member 36 is configured by sandwiching the charging wire 2f with a sponge member having diamond abrasive grains attached to its surface, and removes the attached toner, external additive, and discharge products by polishing the surface of the charging wire 2f. The cleaning member 36 is retracted to a standby position outside the discharge region during the charging operation of the charging unit 2, and moves in the front-rear direction during the non-charging operation to clean the charging wire 2f. The cleaning operation of the charging wire 2f by the cleaning member 36 is mainly performed before and after the printing operation, when the power of the image forming apparatus is turned on and off, and during adjustment during the operation of mass printing.

[0033] (Duct) Next, the configuration of the duct 50 will be described with reference to FIGS. 5 and 6. FIG. 5 is a schematic perspective view of the duct 50 according to the first embodiment. FIG. 6 is a schematic cross-sectional view of the duct 50 according to the first embodiment.

[0034] The duct 50 has an inlet 50a which is an opening for taking in air, and an outlet 50b which is an opening for discharging air. The inlet 50a of the duct 50 is a square-shaped opening, and is provided in an exterior cover (not shown) on the front side of the image forming apparatus A. A fan 51 (see FIG. 2) for generating an air flow for taking in the air outside the image forming apparatus A into the duct 50 is attached to the inlet 50a of the duct 50. Further, the outlet 50b of the duct 50 is a rectangular opening formed in accordance with the longitudinal shape of the charging unit 2, and is disposed at a position facing the charging unit 2 over the longitudinal direction of the charging unit 2.

[0035] Also, the outlet 50b of the duct 50 is provided so as to extend in the direction of the rotation axis (front-rear direction) and is disposed above the charging unit 2 in the vertical direction. Therefore, the duct 50 has a first flow path 50c extending from the front to the rear of the image forming apparatus A and a second flow path 50d extending downward in the vertical direction while bending in the left-right direction of the image forming apparatus A in order to guide air toward the charging unit 2. The air taken into the first flow path 50c from the inlet 50a of the duct 50 by the air flow generated by the fan 51 is discharged from the outlet 50b through the second flow path 50d and sent to the charging unit 2.

[0036] In this embodiment, the front side of the image forming apparatus A is the side where the user normally stands to operate an operation panel (not shown) for setting related to image formation, and the rear side of the image forming apparatus A is the opposite side. The left side of the image forming apparatus A is the left side when viewed from the front side, and the right side is the right side when viewed from the front side. Also, the front-rear direction of the image forming apparatus A and the direction of the rotation axis of the photosensitive drum 1 are the same direction, and the left-right direction of the image forming apparatus A and the rotation direction of the photosensitive drum 1 are the same direction. Also, the direction perpendicular to the front-rear direction and the left-right direction defined here is defined as the upward direction in the vertical direction and the downward direction in the vertical direction. The forward direction F, rearward direction B, right direction R, left direction L, upward direction U, and downward direction D defined here are shown in FIGS. 1, 2, 5, etc.

[0037] Here, as in the relationship between the inlet 50a and the outlet 50b of the duct 50, vortices of air are likely to occur at the portion where the cross-sectional shape of the duct 50 changes. For this reason, even if air is taken in at a uniform flow velocity from the inlet 50a of the duct 50, the flow velocity of the air discharged from the outlet 50b becomes non-uniform or the air is likely to flow backward. Also, when the air flow path bends like the first flow path 50c and the second flow path 50d of the duct 50, the air flow is likely to be disturbed, the flow velocity of the air discharged from the outlet 50b becomes non-uniform, and the air is likely to flow backward.

[0038] When the flow velocity of the air discharged from the outlet 50b of the duct 50 is non-uniform and the flow velocity of the air sent into the charging unit 2 is non-uniform in the longitudinal direction of the charging unit 2 (the direction of the rotation axis of the photosensitive drum 1), vortices are likely to occur inside the charging unit 2. When vortices occur inside the charging unit 2, external additives such as toner and silica adhering to the surface of the photosensitive drum 1 may be lifted up and adhered to the charging wire 2f, resulting in a decrease in charging performance, or uneven ventilation of discharge products may occur, leading to uneven corrosion of the charging wire 2f and the grid plate.

[0039] Therefore, in order to suppress the disturbance of the air flow and the non-uniformity of the air flow velocity and the reverse flow of air near the outlet 50b of the duct 50, a plurality of flow dividing plates 60 are provided near the outlet 50b inside the duct 50. The plurality of flow dividing plates 60 are provided in parallel along the rotation axis direction (front-rear direction) of the photosensitive drum 1 at a position between the inner wall 50e and the inner wall 50f of the duct 50.

[0040] The flow dividing plate 60 is a plate-like member (flow dividing member) extending in a direction (left-right direction or vertical direction) perpendicular to the rotation axis direction (front-rear direction) of the photosensitive drum 1, and distributes and flows the air taken in from the inlet 50a of the duct 50 toward the outlet 50b. In this embodiment, 53 flow dividing plates 60 (flow dividing plates 6001 to 6053) are provided as the flow dividing members. Therefore, the air taken in from the inlet 50a of the duct 50 is distributed by the 53 flow dividing plates 60 (6001 to 6053) into a plurality of flow paths 61 (here, 54 flow paths 6101 to 6154) toward the outlet 50b. Here, the plurality of flow dividing plates 6001 to 6053 of the duct 50 are provided at equal intervals along the rotation axis direction (front-rear direction) of the photosensitive drum 1, and form a plurality of flow paths (blowing regions) 6101 to 6154 equally divided in the rotation axis direction. Each of the flow dividing plates 6001 to 6053 distributes and flows the air taken in from the inlet 50a of the duct 50 to one of the plurality of flow paths 6101 to 6154 divided in the rotation axis direction of the photosensitive drum 1 and a region on the downstream side of that one flow path.

[0041] The outlet 50b of the duct 50 is formed and surrounded by the front inner wall 50e and the rear inner wall 50f in the front - rear direction, and the left inner wall 50g and the right inner wall 50h in the left - right direction. The outlet 50b of this duct 50 is provided to face the discharge region 34 of the charging wire 2f in the direction of the rotation axis of the photosensitive drum 1. In other words, the inner walls 50e, 50f, 50g, and 50h forming the outlet 50b of the duct 50 face the discharge region 34 (the first region) of the charging wire 2f and form a first air passage 31 that performs uniform air blowing with respect to the discharge region 34 (the first region) of the charging wire 2f.

[0042] (Duct air passage switching configuration) On the other hand, even if uniform air blowing is performed in the front - rear direction (longitudinal direction) with respect to the discharge region 34 (the region indicated by the dashed - dotted line in FIG. 3) of the charging unit 2, if charging is performed for a long time, there is a possibility that ozone and discharge products will accumulate in the regions outside the discharge region 34 in the front - rear direction. Hereinafter, the region outside the discharge region 34 in the front - rear direction is referred to as the ozone retention region 33. In this case, the attachment of discharge products to the ozone retention region 33 of the charging wire 2f occurs, leading to corrosion of the charging wire 2f, a decrease in the strength of the charging wire 2f due to corrosion, and even breakage of the charging wire 2f. Note that as the ozone retention region 33 outside the discharge region 34 in the front - rear direction, there are the gap regions between the front block 2a and the rear block 2b and the photosensitive drum 1 where air blowing cannot be directly performed, and the vicinity of the support member for stretching the charging wire 2f provided between the blocks 2a and 2b.

[0043] Therefore, in the present embodiment, as shown in FIG. 7, when the charging unit 2 is in the non - charging operation, it has a configuration that can be switched from the aforementioned first air passage 31 to a second air passage 32 that blows air to the ozone retention region 33, which is the region outside the discharge region 34. The duct 50 has inner walls 50e and 50f, which are air - direction switching members that can move between a first position forming a first air passage 31 facing the discharge region 34 of the charging wire 2f and a second position forming a second air passage 32 facing the ozone retention region 33 of the charging wire 2f.

[0044] Here, a configuration in which wind direction switching members (inner walls 50e and 50f) are provided on one side and the other side in the axial direction of the duct 50 is illustrated as an example, but the present invention is not limited thereto. The wind direction switching members may be provided on either one or three or more of them, and any configuration may be used as long as they are provided at at least one location of the duct 50.

[0045] The switching from the first air passage 31 to the second air passage 32 is performed by moving the front inner wall 50e and the rear inner wall 50f in the front-rear direction of the duct 50 facing the discharge region 34 of the charging unit 2 from the first position to the second position. The movement of the inner walls 50e and 50f from the first position to the second position is performed by the operation of the cleaning member 36 described above. That is, the inner walls 50e and 50f forming the outlet 50b of the duct 50 are moved to the first position shown in Fig. 8(a) and the second position shown in Fig. 8(b) around the axis by the operation of the cleaning member 36, thereby switching the air passage.

[0046] Here, the first position shown in Fig. 8(a) is a position where the inner walls 50e and 50f forming the outlet 50b of the duct 50 form the first air passage 31 facing the discharge region 34 of the charging unit 2, and is a position for performing uniform air blowing to the discharge region 34. The second position shown in Fig. 8(b) is a position where the inner walls 50e and 50f forming the outlet 50b of the duct 50 form the second air passage 32 facing the ozone retention region 33 outside the discharge region 34 of the charging unit 2 in the longitudinal direction, and is a position for blowing air to the ozone retention region 33.

[0047] The inner wall 50e is a duct wall that forms the outlet 50b of the duct 50 at the front end (one side in the longitudinal direction) in the front-rear direction of the duct 50. The inner wall 50e is provided so as to be movable between the first position shown in Fig. 8(a) and the second position shown in Fig. 8(b) rotated forward from the first position around the axis. In other words, the inner wall 50e is a wind direction switching member movable between the first position and the second position.

[0048] The inner wall 50e is provided at the end on the side of the standby position where the cleaning member 36 retreats outside the discharge region during the charging operation in the moving direction (front-rear direction) of the cleaning member 36. A link member 52 that is rotatable about an axis is provided on the front side in the front-rear direction of the duct 50 provided with the inner wall 50e. The link member 52 is provided at a position where it contacts the inner wall 50e. Here, the link member 52 is not limited to a configuration that contacts the inner wall 50e, and it may also be configured to be connected to the inner wall 50e. Further, the link member 52 is provided at a position where it contacts the cleaning member holder 37 when the cleaning member holder 37 holding the cleaning member 36 moves to the standby position shown in FIG. 8(a). The inner wall 50e is pressurized in the direction of moving from the first position to the second position by a pressurizing member 53. Here, the pressurizing member 53 uses a tension spring using a wire, but it is not limited to this.

[0049] The inner wall 50e is held at the first position shown in FIG. 8(a) against the pressing force of the pressurizing member 53 by contact with the link member 52 that has contacted the cleaning member holder 37 moved to the standby position. Further, the inner wall 50e is moved from the first position to the second position as the cleaning member holder 37 moves in the direction of the rotation axis from the standby position. Specifically, when the cleaning member holder 37 moves in the direction of the rotation axis to perform the cleaning operation and the contact with the link member 52 is released, the inner wall 50e is moved from the first position to the second position shown in FIG. 8(b) by the pressing force of the pressurizing member 53. Furthermore, the inner wall 50e is moved from the second position to the first position as the cleaning member holder 37 retreats to the standby position. Specifically, when the cleaning member holder 37 moves back to the standby position and contacts the link member 52 and the link member 226 is rotated, the inner wall 50e is moved from the second position to the first position against the pressing force of the pressurizing member 53.

[0050] The inner wall 50f is a duct wall that forms the outlet 50b of the duct 50 at the rear end (the other side in the longitudinal direction) of the duct 50 in the front-rear direction. The inner wall 50f is provided movably between a first position shown in Fig. 8(a) and a second position shown in Fig. 8(b) which is rotated rearward from the first position about the axis. In other words, the inner wall 50f is a wind direction switching member movable between the first position and the second position.

[0051] The inner wall 50f is provided at an end opposite to the standby position where the cleaning member 36 retreats outside the discharge area during the charging operation in the moving direction (front-rear direction) of the cleaning member 36. The inner wall 50f is pressurized in the direction of moving from the second position shown in Fig. 8(b) to the first position shown in Fig. 8(a) by the pressurizing member 54. Here, the pressurizing member 54 uses a tension spring using a wire, but is not limited thereto.

[0052] During the non-charging operation, the inner wall 50f is pressurized by the pressurizing member 54, abuts against a stopper (or the end of the shield plate) not shown, and its position is regulated, and it is held at the first position shown in Fig. 8(a). Further, the inner wall 50f is moved from the first position to the second position as the cleaning member holder 37 moves in the direction of the axis of rotation from the standby position. Specifically, when the cleaning member holder 37 holding the cleaning member 36 moves in the direction of the axis of rotation to perform the cleaning operation, the inner wall 50f is moved from the first position to the second position against the pressing force of the pressing member 54 by the contact between the cleaning member holder 37 and the inner wall 50f. Furthermore, the inner wall 50f is moved from the second position to the first position as the cleaning member holder 37 retreats to the standby position. Specifically, when the cleaning member holder 37 is moved back to the standby position again, the inner wall 50f is moved from the second position to the first position by the pressing force of the pressing member 54.

[0053] In this way, when the inner walls 50e and 50f, which are the wind direction switching members, are performing the charging operation, the first air passage 31 is formed at the solid line position (the first position) shown in Fig. 8(a), and uniform air blowing is performed on the discharge region 34 of the opposing charging unit 2. Thereby, it is possible to suppress the retention of discharge products and the adhesion of discharge products in the discharge region.

[0054] On the other hand, when the inner walls 50e and 50f are not performing the charging operation, the second air passage 32 is formed at the solid line position (the second position) shown in Fig. 8(b), and air blowing is performed on the ozone retention region 33 of the opposing charging unit 2. Thereby, it is also possible to suppress the retention of discharge products and the adhesion of discharge products in the ozone retention region outside the discharge region.

[0055] In addition, the movement of the inner walls 50e and 50f, which are the wind direction switching members, from the first position to the second position is performed by the operation of the cleaning member holder 37 described above. Thereby, in addition to the above-described effects, it is not necessary to newly provide a member for moving the inner wall, and simplification of the configuration, cost reduction, and miniaturization of the apparatus can be achieved.

[0056] (Shielding portion) Furthermore, when the inner wall 50f, which is the wind direction switching member, moves from the first position to the second position, it is more preferable that a part of the air passage in the duct facing the discharge region 34 of the charging unit 2 is shielded.

[0057] For example, as shown in Fig. 9, a shielding portion 55 that can move to a position where a part of the outlet 50b of the duct 50 is shielded is provided. Here, the shielding portion 55 is provided on some of the shunt plates 6049 to 6052 among a plurality of shunt plates 60 arranged in parallel along the rotation axis direction of the photosensitive drum 1 inside the duct 50. The connection between each of the shunt plates 6049 to 6052 and each of the shielding portions 55 is such that, for example, a part of each of the shielding portions 55 is rotatably supported by each of the shunt plates 6049 to 6052. Note that the configuration in which the shielding portion 55 is provided on the shunt plate 60 is not limited, and a configuration in which the shielding portion is provided separately and independently from the shunt plate is also acceptable.

[0058] In addition, each shielding portion 55 is connected to a link member 56 that is movably provided in the direction of the rotation axis. The link member 56 is connected to an inner wall 50f that is a wind direction switching member. Therefore, during the non-charging operation, since the cleaning member holder 37 is retracted to the standby position and the inner wall 50f is pressed by the pressing member and held at the first position, the shielding portion 55 is held at the position shown by the two-dot chain line (third position) in FIG. 9. Further, when the cleaning member holder 37 that holds the cleaning member 36 moves in the direction of the rotation axis to perform the cleaning operation, when the inner wall 50f moves from the first position to the second position due to the contact between the cleaning member holder 37 and the inner wall 50f, the shielding portion 55 moves to the solid line position (fourth position) shown in FIG. 9 that shields a part of the space partitioned by the flow dividing plate 60 in the duct 50. Furthermore, when the cleaning member holder 37 moves back to the standby position and the inner wall 50f moves from the second position to the first position, the shielding portion 55 moves to the position shown by the two-dot chain line in FIG. 9.

[0059] Note that the configuration in which the shielding portion 55 is connected to the inner wall 50f that is one of the wind direction switching members is not limited thereto, and the configuration in which the shielding portion 55 is connected to the inner wall 50e that is the other wind direction switching member or the configuration in which the shielding portion 55 is connected to both wind direction switching members may be employed.

[0060] In this way, the link member 56 moves in the direction of the arrow together with the inner wall 50f that is a wind direction switching member, so that the shielding portion 55 is rotated. By shielding a part of the air passage in the duct 50 with the shielding portion 55, the air volume passing through the shielding portion 55 is reduced, and accordingly, the air volume in the vicinity of the inner wall 50f can be increased, and the air can be blown more efficiently into the ozone retention region 33.

[0061] As described above, when the wind direction switching member moves from the first position to the second position by the operation of the cleaning member, it becomes possible to ventilate the ozone retention region outside the discharge region during the non-charging operation, and the retention of the discharge products and the adhesion of the discharge products outside the discharge region can be suppressed.

[0062] 〔Embodiment 2〕 The image forming apparatus according to Example 2 will be described. Since the schematic configuration of the image forming apparatus is the same as that of Example 1 described above, the description thereof will be omitted here.

[0063] (Duct air flow switching configuration) Also in this embodiment, a configuration is provided that can be switched to a second air passage 32 that blows air from the aforementioned first air passage 31 to an ozone retention region 33, which is a region outside the discharge region 34, during the non-charging operation of the charging unit 2.

[0064] In the above-described embodiment, an example of the configuration in which the duct 50 has inner walls 50e and 50f, which are air direction switching members movable between a first position and a second position, was illustrated. However, in this embodiment, instead of this configuration, the following configuration is provided.

[0065] In this embodiment, as shown in FIGS. 10(a) and 10(b), the cleaning member holder 37 has an air direction switching portion 37a that moves from a standby position where uniform air is blown to the discharge region during the charging operation to an air passage forming position where air is blown to the ozone retention region during the non-charging operation.

[0066] The configuration of the duct and the cleaning member according to Example 2 will be described with reference to FIGS. 10(a) and 10(b). FIGS. 10(a) and 10(b) are schematic cross-sectional views of the duct and the cleaning member according to Example 2. Note that members having the same functions as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0067] The air direction switching portion 37a is provided on one side in the moving direction of the cleaning member holder 37. Note that the air direction switching portion 37a is not limited to one side in the moving direction of the cleaning member holder 37, and may be provided on both sides.

[0068] Further, the air direction switching portion 37a is integrally formed with the cleaning member holder 37 that holds the cleaning member 36. Note that the air direction switching portion 37a is not limited to the configuration of being integrally formed with the cleaning member holder 37, and may be provided separately as long as it moves together with the cleaning member holder 37.

[0069] When the wind direction switching part 37a moves in the direction of the rotation axis from the standby position shown in Fig. 10(a) where the cleaning member holder 37 has retracted outside the discharge area 34 of the charging part 2, it moves from the standby position to the air passage forming position shown in Fig. 10(b). Here, the air passage forming position of the wind direction switching part 37a shown in Fig. 10(b) is a position where an air passage 32 is formed facing the ozone retention area 33 outside the discharge area 34 in the direction of the rotation axis.

[0070] Note that the ozone retention area 33 facing the air passage 32 (second air passage) is an area that cannot be completely covered only by the air blown from the first air passage 31 of the duct 50. Therefore, the ozone retention area 33 is not limited to only the area outside the discharge area 34 of the charging part 2, and it may include a part close to the outside of the discharge area even within the discharge area.

[0071] The wind direction switching part 37a is provided on the cleaning member holder 37 and is movably provided together with the cleaning member holder 37 between the standby position shown in Fig. 10(a) where uniform air is blown into the discharge area 34 and the air passage forming position shown in Fig. 10(b) where air is blown into the ozone retention area. When the cleaning member 36 and the cleaning member holder 37 move in the direction of the rotation axis from the standby position to perform cleaning, the wind direction of the air discharged from the duct 50 switches from the first air passage 31 to the second air passage 32. As a result, it becomes possible to ventilate the ozone retention area outside the discharge area during the non-charging operation.

[0072] (Shielding part) Furthermore, it is more preferable that when the wind direction switching part 37a of the cleaning member holder 37 moves from the standby position to the air passage forming position, a part of the air passage in the duct facing the discharge area 34 of the charging part 2 is shielded.

[0073] For example, as shown in FIG. 11, the cleaning member holder 37 has a shielding portion 57 that shields a part of the outlet 50b of the duct 50. The shielding portion 57 is moved to a position where it shields a part of the outlet 50b of the duct 50 when the cleaning member 36 and the cleaning member holder 37 are moved from the standby position to the air passage forming position. Thereby, the air volume of the shielding portion 57 can be reduced, and accordingly, the air volume of the air direction switching portion 37a can be increased, enabling more efficient blowing of air into the ozone retention region 33.

[0074] Furthermore, a shielding sheet 58 that contacts the shielding portion 57 of the cleaning member holder 37 moved to the air passage forming position is provided on a part of the plurality of flow dividing plates 60. The shielding sheet 58 is provided at the end of the flow dividing plate 60 on the duct outlet side and is a flexible member formed of a plastic sheet or the like. By inserting the shielding sheet 58 into the shielding portion 57, the outlet 50b of the duct 50 can be shielded more effectively. By shielding a part of the air passage with the shielding portion 57, the air volume of the air direction switching portion 37a can be increased, enabling more efficient ventilation of the ozone retention region.

[0075] As described above, by the operation of the cleaning member, when the air direction switching portion moves from the standby position to the air passage forming position, it becomes possible to ventilate the ozone retention region outside the discharge region during the non-charging operation, and it is possible to suppress the retention of discharge products and the adhesion of discharge products outside the discharge region.

Explanation of Reference Numerals

[0076] A … Image forming apparatus 1 … Photosensitive drum (photoconductor) 2 … Charging unit (charger) 2a … Front block 2b … Rear block 2c … First shield plate (shielding member) 2d … Second shield plate (shielding member) 2e … Grid plate 2f … Charging wire (discharge wire) 31 … First air passage 32 … Second air passage 33 … Ozone retention area (second area) 34 … Discharge area (first area) 36 … Cleaning member 37 … Cleaning member holder 37a … Wind direction switching part 38 … Lead screw 50 … Duct 50a … Inlet 50b … Outlet (opening) 50c … First flow path 50d … Second flow path 50e … Inner wall (wind direction switching member) 50f … Inner wall (wind direction switching member) 51 … Fan 52, 56 … Link member 53, 54 … Pressurizing member 55, 57 … Shielding part 58 … Shielding sheet 60 … Flow dividing plate (flow dividing member) 70 … Exhaust duct

Claims

1. A photoreceptor, a charger having a discharge wire stretched in the direction of the rotation axis of the photoreceptor for charging the surface of the photoreceptor to a predetermined potential, a cleaning member provided movably in the direction of the rotation axis for cleaning the discharge wire, a duct provided facing the discharge wire and having an opening extending in the direction of the rotation axis for guiding external air to the discharge wire through the opening, comprising: the duct has a wind direction switching member provided at at least one location of the duct and movable between a first position forming a first air passage facing a first region of the discharge wire and a second position forming a second air passage facing a second region outside the first region of the discharge wire in the direction of the rotation axis, the wind direction switching member is moved from the first position to the second position as the cleaning member moves in the direction of the rotation axis from a standby position retracted outside the first region, an image forming apparatus characterized by the above.

2. The movement of the wind direction switching member from the first position to the second position is performed by contact between the cleaning member and the wind direction switching member. The image forming apparatus according to claim 1, characterized by the above.

3. having a link member connected to the wind direction switching member and provided at a position contacting the cleaning member at the standby position, the movement of the wind direction switching member from the first position to the second position is performed by release of contact between the cleaning member and the link member. The image forming apparatus according to claim 1, characterized by the above.

4. having a shielding portion connected to the wind direction switching member and provided movably at a position shielding a part of the opening of the duct, the shielding portion is moved to a position shielding a part of the opening of the duct when the wind direction switching member is moved from the first position to the second position. The image forming apparatus according to claim 1, characterized by the above.

5. a fan for generating an air flow for taking in external air of the image forming apparatus into the duct, a plurality of flow dividing plates arranged in parallel along the direction of the rotation axis of the photoreceptor inside the duct, a part of the plurality of flow dividing plates has the shielding portion. The image forming apparatus according to claim 4, characterized by the above.

6. the wind direction switching member is provided on at least one side of the duct in the direction of the rotation axis. The image forming apparatus according to claim 1, characterized by the above.

7. The wind direction switching member is moved from the second position to the first position along with the operation of the cleaning member retracting to the standby position. The image forming apparatus according to claim 1, characterized in that.

8. A photoreceptor; A charger having a discharge wire stretched in the axial direction of the photoreceptor, for charging the surface of the photoreceptor to a predetermined potential; A cleaning member provided movably in the axial direction, for cleaning the discharge wire; A duct provided opposite to the discharge wire, having an opening stretched in the axial direction, for guiding external air to the discharge wire through the opening; Comprising: The cleaning member has a wind direction switching portion that moves to a wind path forming position that forms a wind path facing an area outside the first area of the discharge wire in the axial direction along with the operation of the cleaning member moving in the axial direction from a standby position where the cleaning member has retracted outside the first area of the discharge wire. The image forming apparatus, characterized in that.

9. The cleaning member has a shielding portion that shields a part of the opening of the duct. The shielding portion is moved to a position that shields a part of the opening of the duct when the cleaning member is moved from the standby position to the wind path forming position. The image forming apparatus according to claim 8, characterized in that.

10. A fan for generating an air flow for taking in external air of the image forming apparatus into the duct; A plurality of flow dividing plates arranged in parallel along the axial direction of the photoreceptor inside the duct; Some of the plurality of flow dividing plates have flexible members that contact the shielding portion of the cleaning member moved to the wind path forming position. The image forming apparatus according to claim 9, characterized in that.

11. The wind direction switching portion is provided on at least one side in the moving direction of the cleaning member. The image forming apparatus according to claim 8, characterized in that.

12. The wind direction switching portion moves from the standby position to the wind path forming position along with the operation of the cleaning member retracting to the standby position. The image forming apparatus according to claim 8, characterized in that.

13. The charger further includes a shield member that surrounds the discharge wire and has an opening provided on the side of the duct that is the side opposite to the photoreceptor side. The duct forms a wind path for guiding the external air to the discharge wire together with the shield member. The image forming apparatus according to any one of claims 1 to 12, characterized in that...

14. The cleaning member is retracted to the standby position during the charging operation of the charger, and moves from the standby position in the direction of the rotation axis during the non-charging operation of the charger to clean the discharge wire. The image forming apparatus according to any one of claims 1 to 12, characterized in that...

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