JP2007241175A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can suck ozone emitted from a charging device to be sucked to a normal ozone exhaust duct. <P>SOLUTION: The image forming apparatus includes a photoreceptor 1Y, a corona charger 2Y for charging the surface of the photoreceptor, an image writing device 3Y for forming an electrostatic latent image on the photoreceptor, a developing unit 4Y for developing the electrostatic image into a toner image, and an ozone exhaust duct 110 which has an inlet port close to the corona charger and sucks and discharges ozone emitted from the corona charger. The image forming apparatus is provided with a shielding part 150 which forms a closed space from the ozone exhaust space of the corona charger and the inlet port of the ozone exhaust duct 110 in cooperation with the photoreceptor 1Y. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus provided with a corona charger, and more particularly to an apparatus including a duct for collecting ozone generated from a corona charger and toner powder scattered from a developing device.

  In the image forming apparatus, ozone is generated from the corona charger along with the corona discharge, and toner is scattered from the developer along with the developing operation. However, these ozone and toner have an undesirable effect on the environment and image quality. It is known to give.

  Concerning ozone, a configuration has been proposed in which the configuration of the corona charger is devised, the generated ozone is forcibly sucked by a suction fan, and an odor is removed by a filter provided along the way.

  For scattered toner, a film sheet is provided between the surface of the photosensitive member and the developing device base that forms the opening for the developing sleeve facing the photosensitive member to create a sealed space, or toner floating in the developing region is removed. There have been proposals such as suction by a suction means and removal by a filter.

  However, although the above-mentioned configuration is useful as it is, it is not yet at a satisfactory level. For example, the image forming apparatus is extremely strict in terms of space, such as a tandem method, particularly an intermediate transfer tandem method. It was not something that could be adapted.

  With respect to such a problem, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-215993), a tandem type image forming apparatus that includes four image forming units in the vertical direction and uses an intermediate transfer member is provided for each image forming unit. A configuration with a duct block is proposed. This duct block has a structure in which an air introduction duct for sending air into the corona charger, an ozone discharge duct for discharging ozone generated from the corona charger, and a toner discharge duct for collecting scattered toner are provided in a hierarchy. It has become.

With such a configuration, the duct block can be reduced in size and handled easily, and can be installed in an image forming apparatus that is extremely space strict, such as a tandem type employing an intermediate transfer method. It was.
JP 2003-215993 A

  However, the above-mentioned Patent Document 1 has a problem that ozone discharged from the corona charger cannot be sucked effectively. That is, the suction port of the ozone discharge duct does not face the charger, but faces the same direction as the ozone flows. This is a configuration adopted in order to ensure the width of the suction port. While the ozone released from the charger flows in the direction of rotation of the photoconductor, the suction port faces the same direction, so the ozone drifts in the space below the developing device, and then enters the ozone discharge duct. It is sucked, passes through the ozone filter and is discharged out of the machine. Still, if the image forming speed is low or medium, most of the ozone can be absorbed by the ozone exhaust duct.

  By the way, as the image forming apparatus increases in speed, the flow of ozone also increases. Further, the rotation of the stirring screw for stirring the toner inside the developing unit and the developing sleeve also increases, and the toner becomes high temperature due to friction. On the other hand, the toner is being fixed at a low temperature, and the high temperature makes it easy for the toner to melt and solidify in the developing device. For this reason, air close to the outside air temperature is sent from the rear of the developing device toward the photosensitive member to cool the developing device. On the other hand, ozone drifts in the space below the developing unit, and the air that cools the developing unit collides with the flow of ozone, so that the ozone that should be sucked into the ozone discharge duct is not sucked into the image forming apparatus There is a possibility that the air is diffused in and discharged from an unintended route such as a cooling fan.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of sucking ozone released from a charger into a regular ozone discharge duct.

  In order to achieve the above object, an image forming apparatus of the present invention includes a photoconductor, a corona charger for charging the surface of the photoconductor, an image writing device for forming an electrostatic latent image on the photoconductor, In an image forming apparatus comprising a developing unit that converts an electrostatic latent image into a toner image, and an ozone discharge duct that has a suction port close to the corona charger and sucks and discharges ozone emitted from the corona charger. The present invention is characterized in that there is provided a shielding portion that is closed together with the photoconductor from the ozone discharge space of the corona charger to the suction port of the ozone discharge duct.

  The ozone discharge duct is installed at a position adjacent to a writing optical path for the image writing device to form an electrostatic latent image on a photoconductor, and at least a part of the shielding portion crosses the writing optical path. Further, at least a portion of the shielding portion that crosses the writing optical path may be transparent.

  Alternatively, a configuration is provided in which a gap is provided between the shielding unit and the photoconductor, or an air introduction duct for sending air to the corona charger is a duct block provided in a hierarchy in the ozone discharge duct. Or a toner discharge duct for discharging scattered toner generated from the developing device, and a layered duct block combined with the ozone discharge duct and the air introduction duct.

  According to the present invention, since the ozone discharge duct is provided with the shielding portion, the ozone generated from the charger collides with the shielding portion and is sucked into the ozone discharge duct to collect most of the ozone, and the ozone leaks to the outside. There is an excellent effect that it is possible to prevent the harmful effects of ozone on the photosensitive drum, such as sensitivity degradation, as much as possible.

  By constructing at least a part of the shielding part in the writing optical path and at least a part of the shielding part in the writing optical path being transparent, the size of the suction port of the ozone discharge duct is ensured to be large. , Ozone can be easily sucked.

  By adopting a configuration having a gap between the front end of the shielding part and the photosensitive member, it is possible to prevent the photosensitive member from being damaged by the shielding part.

  The ozone discharge duct and the air introduction duct are arranged in a hierarchy, and in addition to these, the toner discharge duct is also arranged in a hierarchy, so that a duct block can be formed even in a tandem type color image forming apparatus having a small installation place. It can be provided. Further, since the ducts are clearly separated by adopting a hierarchical structure, the three winds, ozone wind, scattered toner wind, and cooling wind, can be successfully controlled.

  An example of an embodiment according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an image forming apparatus as an embodiment of the present invention. However, the duct block is omitted for convenience. As shown in FIG. 1, this image forming apparatus is called a tandem color image forming apparatus, and includes an automatic document feeder 30, an image reading device 60, image writing devices 3Y, 3M, 3C, and 3K, and a photoreceptor 1Y. , 1M, 1C, 1K, chargers 2Y, 2M, 2C, 2K, developing devices 4Y, 4M, 4C, 4K, fixing device 24, image carrier 6 comprising an intermediate transfer belt, paper feed cassettes 20a, 20b, 20c, A conveyance system 22 and the like are included.

  5Y, 5M, 5C, and 5K are toner replenishing units that replenish new toner to the developing devices 4Y, 4M, 4C, and 4K, respectively.

  The automatic document conveying means 30 is means for automatically conveying a double-sided or single-sided original d. The image reading device 60 is a device that reads image information by a scanning optical system. The image reading device 60 reflects the contents of a large number of originals d fed from the original placement table by three movable mirrors 60c, and collects the condensing lens 60b. Thus, an image is formed on the image sensor 60a made of a CCD and read.

  The image forming unit 10Y that forms a yellow image includes a charger 2Y, an image writing device 3Y, a developing device 4Y, and a cleaning device 8Y disposed around a photoreceptor 1Y as an image carrier. The image forming unit 10M that forms a magenta image includes a photoconductor 1M as an image carrier, a charger 2M, an image writing device 3M, a developing device 4M, and a cleaning device 8M. The image forming unit 10C that forms a cyan image includes a photoreceptor 1C as an image carrier, a charger 2C, an image writing device 3C, a developing device 4C, and a cleaning device 8C. The image forming unit 10K that forms a black image includes a photoreceptor 1K as an image carrier, a charger 2K, an image writing device 3K, a developing device 4K, and a cleaning device 8K. The charger 2Y and the image writing device 3Y, the charger 2M and the image writing device 3M, the charger 2C and the image writing device 3C, and the charger 2K and the image writing device 3K constitute a latent image forming unit for each color. To do.

  The image carrier 6 as an intermediate transfer belt is an endless belt, is stretched by a plurality of rollers, and is rotatably supported. The image carrier 6 is provided with a cleaning device 9. The cleaning device 9 includes a cleaning roller and a cleaning blade.

  A signal of image information formed on the image sensor 60a is sent to an image processing unit (not shown). The image processing unit performs analog processing, A / D conversion, shading correction, image compression processing, and the like, and then sends a signal for each color to the image writing devices 3Y, 3M, 3C, and 3K.

  In the image writing apparatuses 3Y, 3M, 3C, and 3K, a semiconductor laser is used as a laser light source, and a light beam emitted from the semiconductor laser is formed into a scanning light beam by an optical element such as a polygon mirror to be used as a photosensitive body as a scanning object. It enters the bodies 1Y, 1M, 1C, and 1K, and forms an electrostatic latent image of each color.

  The respective color images formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred onto the rotating image carrier 6 by transfer devices 7Y, 7M, 7C, and 7K as primary transfer devices (1). Next transfer), a synthesized color image is formed. The paper P accommodated in the paper feed cassettes 20a, 20b, and 20c is fed by the paper feed means 21a, 21b, and 21c, passes through the transport system 22, and is timed by the registration roller 23 as a secondary transfer device. The color image is transferred onto the paper P by being conveyed to the transfer device 7a (secondary transfer). The sheet P on which the color image has been transferred is subjected to fixing processing by the fixing device 24, is sandwiched between the sheet discharge rollers 25, and is placed on the sheet discharge tray 26 outside the apparatus.

  On the other hand, after the color image is transferred onto the paper P by the transfer device 7a, the image carrier 6 from which the paper P has been separated is cleaned by the cleaning device 9.

  FIG. 2 is a diagram showing a main part of the image forming apparatus of FIG. FIG. 3 is an enlarged view of one duct block 100 of FIG. 2 and its periphery, and FIG. 4 is a perspective view showing a configuration of the duct block 100 in a partial cross section.

  The four color image forming units of yellow (Y), magenta (M), cyan (C), and black (K), the image carrier 6 as an intermediate transfer member, and the like are mounted on a process stand (not shown). This process frame can be taken in and out in a direction perpendicular to the paper surface via a rail (not shown) provided on the apparatus main body side. The chargers 2Y, 2M, 2C, and 2K can also be attached and detached in the direction perpendicular to the paper surface.

  The duct block 100 according to the present invention is disposed between the chargers 2Y, 2M, 2C, and 2K and the developing devices 4Y, 4M, 4C, and 4K corresponding to the chargers. In the following description, the duct block 100 provided between the charging device 2Y and the developing device 4Y will be described. However, unless otherwise specified, the other charging devices 2M, 2C, 2K and the developing devices 4M, 4C, 4K. The duct block 100 provided between the two has the same configuration.

  The duct block 100 has a structure in which three ducts 110, 120, and 130 divided by partition walls 101, 102, 103, and 104 are layered.

  The air introduction duct 120 in the middle is a duct for guiding the outside air into the charger, and the ozone discharge duct 110 formed thereon is ozone discharged from the charger 2Y (with the operation of the corona discharge electrode). This is a duct for removing and discharging from the charger 2Y or its surroundings.

  The ozone exhaust duct 110 is formed between a partition wall 101 at the top of the duct block 100 and a partition wall 102 that serves as a boundary between the air introduction duct 120. The suction port of the ozone discharge duct 110 is located downstream of the charger 2Y when viewed in the rotation direction (counterclockwise direction) of the photoreceptor 1Y.

  Attaching means (described later) for attaching the charger 2Y is located near the photosensitive body 1Y of the partition wall 103. With the charger 2Y attached, the bottom surface of the charger 2Y and the partition wall 103 facing the back of the charger 2Y are provided. A space 121 is formed between them. A hole is formed in the bottom surface of the charger 2Y so that air supplied from the air introduction duct 120 passes through the charger 2Y and reaches the photoreceptor 1Y.

  The lower developing device 4M having the same shape as the lower surface of the duct block 100 (specifically, the lower surface including the partition wall 103 portion inclined obliquely to the left) and the lower surface of the partition wall 103. The upper surface of the partition wall 101 forms a passage 105 for discharging the toner that connects the vicinity of the developing region and the toner discharge duct 130 located away from the photoreceptor 1Y. A seal 104a is provided at the tip of the partition wall 104 to close the space between the partition wall 101 of the lower developing device 4M.

  The duct block 100 is configured by connecting four partition walls made of a resin molded product with screws or the like. Further, one end portions of the ozone discharge duct 110 and the toner discharge duct 130 are open, and although not shown, the ozone discharge duct 110 and the toner discharge duct 130 are connected to suction means such as a fan through one duct provided in the process frame, Has a filter containing activated carbon for removing ozone and a filter for adsorbing toner, and these are exchangeable.

  The air introduction duct 120 is also connected to another duct provided in the process frame. This duct is provided with a fan or the like, and sends outside air to the photoreceptor 1Y through the charger 2Y.

  The toner discharge duct 130 communicates with a passage 105 formed by the wall surface 103 of the duct block 100 and the partition wall 101 of the developing device 4M below the duct block 100. A synthetic resin seal 104a is provided at the tip of the partition wall 104, which is a connecting portion between the toner discharge duct 130 and the passage 105, and serves as a guide for the scattered toner to smoothly flow into the toner discharge duct 130 from the passage 105. Yes.

  The duct block 100 provided on the lower side of the lowermost developing device 4K does not have the next developing device below the duct block 100. Therefore, by providing a plate having the same shape as the uppermost partition wall 101 of the developing device, the passage 105 is formed. Will form.

  Of the three ducts of the duct block 100 provided in each image forming unit, the ozone discharge duct 110 and the toner discharge duct 130 are connected to the suction means at the ends, and a forced air flow is stably generated. Then, ozone or toner coming out of the charger or developing device is transferred through the duct, and ozone odor and scattered toner are adsorbed and removed by the filter.

  Further, when the photoreceptor 1Y rotates, an air flow (surface flow) is generated around the photoreceptor 1Y. As a result, the atmospheric pressure in the vicinity of the charger 2 </ b> Y decreases, and outside air is taken in from the air introduction duct 120. Since the photoconductor 1Y is rotating, the air that has passed through the charger 2Y reaches the surface of the photoconductor 1Y, and is drawn by the rotation of the photoconductor 1Y and merges with the surface layer flow. This surface layer flow moves ozone in and around the charger 2Y in the rotation direction of the photoreceptor 1Y.

  As shown in FIG. 4, at both ends of the partition wall 103 where the charger 2Y is positioned, frames 106 for receiving the charger 2Y are provided in a direction orthogonal to the partition wall surface, and the front side (longitudinal) The charger mounting means 107 is provided on the partition wall 103 which is the inner side in the direction.

  The charger mounting means 107 includes biasing means for biasing the charger 2Y in the upper left direction in the drawing, that is, in a direction close to the peripheral surface of the photoreceptor 1Y. Specifically, the charger 2Y is biased in one direction by a spring. It is made up of energized rollers. With this configuration, a space 121 can be formed between the bottom surface of the charger 2Y and the partition wall 103.

  The exposure means 108 is made up of an array of LEDs, and plays the role of irradiating the photoreceptor 1Y before charging by the charger 2Y to erase the traces of the electrostatic image.

  The partition walls 101, 102, 103, 104 constituting the duct block 100 are coupled by dowels, screws 109, or the like, or like the partition wall 104 and the partition wall 103, a recess is prepared on one side and a projection is prepared on the other, By engaging the protrusions in the recesses, engagement can be achieved by adhesion or the like.

  As is apparent from FIG. 4, the partition wall 102 and the partition wall 104 are partitioned by a plurality of vertically standing partition walls, and the partition width is set so that uniform suction can be achieved in the longitudinal direction on the suction side. Etc. are devised.

  The above configuration is the same as that described in Patent Document 1. According to this configuration, the suction port of the ozone discharge duct 110 is wide but upward. If it is a low-speed machine or a medium-speed machine, this is sufficient, but when it becomes a high-speed machine, the wind for cooling the developing device 4Y flows as shown by an arrow from the right in FIG. This blows into the writing optical path 200 between the developing unit 4Y and the duct block 100, collides with the ozone drifting here, and the ozone diffuses into the apparatus.

  The present invention is characterized in that a shielding portion 150 is provided at the tip of the partition wall 101 in order to prevent this. The material of the shielding part 150 is not particularly limited, and may be the same material as the partition wall 101 or may be different. In this embodiment, the shielding part 150 has a flat plate shape, and is formed separately from the partition wall 101 by bonding or the like. The connection between the shielding part 150 and the partition wall 101 may be a screw. Further, it is possible to extend the partition wall 101 to form a shield unit 150.

  Next, a method for discharging ozone by the image forming apparatus of the present invention will be described.

  When image formation starts, the photoreceptor 1Y rotates counterclockwise, and the charger 2Y uniformly charges the surface of the photoreceptor 1Y by corona discharge. The charged surface of the photoreceptor 1Y is irradiated with a laser beam from the image writing device 3Y along the writing optical path 200 to form a yellow electrostatic latent image on the photoreceptor 1Y. Thereafter, an electrostatic latent image of each color is formed as described with reference to FIG. 1, becomes a toner image, transferred to the image carrier 6, forms an image on paper, and is fixed by the fixing device 24.

  In such an image forming process, when the photoreceptor 1Y rotates, the air on the surface of the photoreceptor 1Y moves together to generate a surface layer flow. Further, ozone is generated from the charger 2Y. The generated ozone rides on the surface layer flow and flows toward the lower part of the developing device 4Y. In the case of Patent Document 1, since there is no shielding part 150, ozone collides with the flow of air sent to cool the developing device 4Y in the space below the developing device 4Y and diffuses in the image forming apparatus. .

  However, since the shielding unit 150 is provided in the present invention, the flow of ozone riding on the surface layer flow toward the lower part of the developing device 4Y hits the shielding unit 150 and stops traveling, and is sucked by the negative pressure of the ozone discharge duct 110. Ozone is removed by a filter containing activated carbon for removing ozone, and it is discharged outside the apparatus as air without ozone.

  If the tip of the shield 150 is in contact with the photoreceptor 1Y, the sealing is improved and ozone can be reliably prevented from passing through, but this is not preferable because the photoreceptor 1Y may be damaged. Therefore, a slight gap is provided between the tip of the shield 150 and the photoreceptor 1Y. Even if there is a gap, it is a slight gap, and since the inside of the ozone discharge duct 110 has a negative pressure, most of the ozone cannot be passed through the gap and is sucked into the suction port of the ozone discharge duct 110 to be deodorized. It can be trapped in and prevent the diffusion of ozone.

  The scattered toner enters the passage 105, passes through the toner discharge duct 130 communicating therewith, and is captured by the filter.

  Since the ozone discharge duct 110 and the toner discharge duct 130 suck air near the charger 2Y, the vicinity of the charger 2Y becomes a low pressure. Therefore, outside air is introduced from the air introduction duct 120. Since these three ducts are separated and arranged in an orderly manner, it is possible to control three winds, that is, a wind containing ozone, a wind containing scattered toner, and a wind supplied from outside.

  If the shielding part 150 is extended in the same plane as the one partition wall 101 of the ozone discharge duct 110, the tip of the shielding part 150 approaches the charger 2Y and narrows the inlet of the ozone discharge duct 110. As shown in the drawing, the tip of the shielding part 150 may be raised slightly upward. However, since the space between the partition wall 101 and the developing device 4Y is a space through which the writing light passes, it is necessary to prevent the tip of the shielding unit 150 from kicking the writing optical path 200.

  In addition, the shape of the shielding part 150 is not limited to a flat surface, and may be any shape. However, if there is a shape that becomes a bottleneck near the suction port, it becomes a resistance and cannot absorb ozone completely. So it should be noted.

  FIG. 5 is a diagram of the second embodiment of the image forming apparatus of the present invention, and corresponds to FIG. 3 of the first embodiment. This embodiment is suitable for a case where the space between the duct block 100 and the developing device 4Y is narrow and the inlet of the ozone discharge duct 110 becomes too narrow when the shielding unit 150 is attached.

  The shield 160 in this embodiment is provided with an L-shaped cross section using transparent glass or synthetic resin so that one side of the L-shaped crosses the writing optical path 200 and the other side is a photoconductor. It is arranged so as to be close to 1Y. By making the shielding part 160 a transparent member, the writing light is not blocked. However, since the optical path length of the writing light changes, it is necessary to adjust the position of the image writing device 3Y so that the imaging position is on the photoreceptor 1Y. It is not necessary to make all of the shielding part 160 transparent, and only the part that crosses the writing optical path 200 needs to be transparent. It is desirable that the portion where the shield 160 crosses the writing optical path 200 is such that the shield 160 and the writing optical path 200 are orthogonal to each other. If they are orthogonal, the imaging position on the photoreceptor 1Y is the same, but if it is tilted, the imaging position will be shifted in the rotational direction.

  By adopting the configuration of the second embodiment, the suction port of the ozone discharge duct 110 is enlarged, and ozone is prevented from diffusing to the lower part of the developing device 4Y, so that air without ozone is discharged to the outside. Can do.

  In an image forming apparatus of a tandem type using an intermediate transfer belt, the size of an apparatus that is inevitably increased is reduced as much as possible, for example, around the drum so that the pitch between the photosensitive drums is minimized. Consider the configuration. For this reason, the space is very severe, and a member cannot be disposed around the photosensitive drum on the side where the intermediate transfer belt is disposed, so that the space becomes smaller.

  However, as in the present invention, it is easy to handle by creating a duct structure for scattering toner removal processing, ozone discharge processing, etc. in a hierarchical manner, and it is small even when mounted on a device having only a small space. Stable processing performance can be exhibited while maintaining the process.

  Also, even if the speed of the image forming apparatus increases or the cooling temperature of the toner advances and the cooling air is sent to the developing device, ozone is sucked through the ozone discharge duct without being affected by the cooling air and leaks outside. It becomes possible not to be.

  In the present embodiment, the charger and the developing unit used in different image forming units are associated with one duct block. However, different from this, for example, one image forming unit. Needless to say, the charging device and the developing device can be associated with one duct box.

  For example, the present invention can also be applied to an image forming apparatus in which an exposure optical system is configured by light emitting diodes (LEDs) arranged in an array in the photosensitive drum. When it is necessary to place the charging device above the developing device, for example, a photosensitive drum is provided on the left side of the intermediate transfer belt in FIG.

  In addition, each image forming unit is arranged horizontally, and the charging unit and the developing unit are provided on the side of the photosensitive drum so that the charging unit is located above. And a developer can be provided in association with the same duct block.

  In this case, if an intermediate transfer belt is used in the same manner as described above, the transfer belt may be disposed horizontally on the lower side of each image forming unit, and the configuration of the image forming apparatus is the intermediate transfer belt. The toner image for each color may be sequentially transferred onto the transfer material without using the toner.

1 is a diagram illustrating a configuration of a first embodiment of an image forming apparatus according to the present invention. 2 shows a main part of the image forming apparatus of FIG. It is the figure which expanded a part of FIG. It is a perspective view which shows the structure of a duct block in a partial cross section. It is a figure of 2nd Example of the image forming apparatus of this invention, and is a figure corresponding to FIG. 3 of 1st Example.

Explanation of symbols

1Y, 1M, 1C, 1K Photoconductors 2Y, 2M, 2C, 2K Corona chargers 3Y, 3M, 3C, 3K Image writing devices 4Y, 4M, 4C, 4K Developer 100 Duct block 110 Ozone exhaust duct 120 Air introduction duct 130 Toner discharge duct 150, 160 Shielding part

Claims (5)

  A photoconductor, a corona charger that charges the surface of the photoconductor, an image writing device that forms an electrostatic latent image on the photoconductor, a developer that converts the electrostatic latent image into a toner image, and the corona charger. In the image forming apparatus having an ozone discharge duct for sucking and discharging ozone emitted from the corona charger, the suction port of the ozone discharge duct from the ozone discharge space of the corona charger. An image forming apparatus characterized in that a shielding portion is provided to make a closed space in cooperation with the photoconductor.   The ozone discharge duct is installed at a position adjacent to a writing optical path for the image writing device to form an electrostatic latent image on a photoconductor, and at least a part of the shielding portion crosses the writing optical path. The image forming apparatus according to claim 1, wherein at least a portion of the shielding portion that crosses the writing optical path is transparent.   The image forming apparatus according to claim 1, wherein a gap is provided between the shielding portion and the photoconductor.   4. The image forming apparatus according to claim 1, wherein the air introduction duct for sending air to the corona charger is a duct block provided in a hierarchy on the ozone discharge duct. 5.   5. The image forming apparatus according to claim 4, further comprising a toner discharge duct for discharging scattered toner generated from the developing unit, and a layered duct block combined with the ozone discharge duct and the air introduction duct. .

Images