Search

EP-4254073-B1 - IMAGE FORMING APPARATUS

EP4254073B1EP 4254073 B1EP4254073 B1EP 4254073B1EP-4254073-B1

Inventors

  • NOJIMA, HIROSHI
  • FUJITA, KEIKO

Dates

Publication Date
20260506
Application Date
20230324

Claims (20)

  1. An image forming apparatus (101) comprising: an image forming unit (500) configured to form an image on a recording material (S); a fan (410) configured to generate an air current; a duct (710) including: an air intake port (720) through which air flows in by an operation of the fan (410); an air discharge port (721) through which air flown in through the air intake port (720) is discharged; and a body portion (740) having a tubular shape and forming an air passage through which air taken in through the air intake port (720) is flown to the air discharge port (721), wherein the body portion (740) includes a holed wall portion (730) in which a plurality of through holes (711) are formed, the plurality of through holes (711) being passed through between an inner surface (730a), forming the air passage, of the holed wall portion (730) and an outer surface (730b), that is on an opposite side from the inner surface (730a), of the holed wall portion (730), the image forming apparatus (101) further comprises a noise absorbing member (715) attached to the outer surface (730b) of the holed wall portion (730) so as to cover the plurality of through holes (711), the noise absorbing member (715) having a noise absorbing property, and in that a side branch to interfere with noise at a specific frequency is not formed at the duct (710).
  2. The image forming apparatus (101) according to claim 1, wherein a ratio of an area occupied by the plurality of through holes (711) to a surface area of an area (725) in which the plurality of through holes (711) are formed on the holed wall portion (730) is 5% or more and 45% or less.
  3. The image forming apparatus (101) according to claim 1 or 2, wherein each of the plurality of through holes (711) is a round hole having a hole diameter of 3 mm or more and 12 mm or less.
  4. The image forming apparatus (101) according to any one of claims 1 through 3, wherein the noise absorbing member (715) is bonded to a bonding surface (723), on which the plurality of the through holes (711) are not formed, of the outer surface (730b) of the holed wall portion (730).
  5. The image forming apparatus (101) according to any one of claims 1 through 4, wherein the body portion (740) includes a first body portion (741) in which a cross-sectional area of the air passage is narrowed from upstream toward downstream in an air current direction of air passing through the air passage, and a second body portion (742) that is formed in succession to a downstream side of the first body portion (741) and in which the cross-sectional area of the air passage is widened from upstream toward downstream in the air current direction, and wherein the holed wall portion (730) is disposed across the first body portion (741) and the second body portion (742).
  6. The image forming apparatus (101) according to claim 5, wherein the holed wall portion (730) includes a bonding surface (723) on which the plurality of through holes (711) are not formed, the bonding surface (723) being disposed on an upstream portion, in the air current direction, of the second body portion (742), and wherein the noise absorbing member (715) is bonded to the bonding surface (723).
  7. The image forming apparatus (101) according to any one of claims 1 through 6, wherein the holed wall portion is a first holed wall portion (730) on which a plurality of first through holes (711) are formed, and the body portion (740) includes a second holed wall portion (731) disposed to face the first holed wall portion (730) interposing the air passage, a plurality of second through holes (711) being formed on the second holed wall portion (731).
  8. The image forming apparatus (101) according to claim 7, wherein the plurality of second through holes (711) are formed so as not to overlap with the plurality of first through holes (711) when viewed in a direction from the outer surface (730b) toward the inner surface (730a).
  9. The image forming apparatus (101) according to claim 7 or 8, wherein the body portion (740) is composed of four sides forming a rectangular cross-section orthogonal to an air current direction of air passing through the air passage, and the first holed wall portion (730) and the second holed wall portion (731) are two sides constituting long sides of the four sides.
  10. The image forming apparatus (101) according to any one of claims 1 through 9, wherein the fan (410) is connected to the air intake port (720) of the body portion (740).
  11. The image forming apparatus (101) according to any one of claims 1 through 10, wherein the fan (410) is a sirocco fan.
  12. The image forming apparatus (101) according to any one of claims 1 through 11, further comprising: a separate duct (703) connected to the fan (410) and having air inside the separate duct (703) sucked by the fan (410); and a filter (412) configured to filter air passing through the separate duct (703).
  13. The image forming apparatus (101) according to any one of claims 1 through 12, wherein the noise absorbing member (715) is formed of ethylene propylene diene rubber.
  14. The image forming apparatus (101) according to any one of claims 1 through 12, wherein the noise absorbing member (715) is formed of a urethane-based foamed body.
  15. The image forming apparatus (101) according to any one of claims 1 through 12, wherein the noise absorbing member (715) is formed of glass wool or rock wool.
  16. The image forming apparatus (101) according to any one of claims 1 through 15, wherein the noise absorbing member (715) is formed in a sheet shape.
  17. The image forming apparatus (101) according to any one of claims 1 through 16, further comprising a casing (500A) configured to store the image forming unit (500), the fan (410), and the duct (710), wherein the image forming unit (500) includes a photosensitive member (201K), a charging unit (202K) configured to charge the photosensitive member (201K), an exposing unit (203K) configured to expose the photosensitive member (201K) being charged to form an electrostatic latent image on the photosensitive member (201K), and a developing unit (204K) configured to develop the electrostatic latent image formed on the photosensitive member (201K) into a toner image using developer, and the duct (710) is configured to guide air surrounding the charging unit (202K) toward an exterior of the casing (500A).
  18. The image forming apparatus (101) according to claim 17, further comprising an air intake fan (408) configured to discharge air surrounding the charging unit (202K) toward the duct (710) and to take in air from the exterior of the casing (500A) toward the charging unit (202K).
  19. The image forming apparatus (101) according to any one of claims 1 through 16, further comprising a casing (500A) configured to store the image forming unit (500), the fan (410), and the duct (710), wherein the image forming unit (500) includes a photosensitive member (201Y, 201M, 201C), a charging unit (202Y, 202M, 202C) configured to charge the photosensitive member (201Y, 201M, 201C), an exposing unit configured to expose the photosensitive member (201Y, 201M, 201C) being charged to form an electrostatic latent image on the photosensitive member (201Y, 201M, 201C), and a developing unit (204Y, 204M, 204C) configured to develop the electrostatic latent image formed on the photosensitive member (201Y, 201M, 201C) into a toner image using developer, and the duct (710) is configured to guide air surrounding the developing unit (204Y, 204M, 204C) to an exterior of the casing (500A).
  20. The image forming apparatus (101) according to claim 19, further comprising an air intake fan (409Y, 409M, 409C) configured to discharge air surrounding the developing unit (204Y, 204M, 204C) toward the duct (710) and to take in air from the exterior of the casing (500A) toward the developing unit (204Y, 204M, 204C).

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an image forming apparatus according to the preamble of claim 1 for forming images on recording materials. Description of the Related Art Image forming apparatuses are equipped with a blowing apparatus disposed within a casing for blowing air in order to collect ozone that is generated when a photosensitive drum is charged and toner that is scattered inside the apparatus, or to discharge heat that has been generated when the apparatus is operated to an exterior of the apparatus. The blowing apparatus includes a fan for generating air current and a tubular duct. The duct forms an air passage that connects the fan with various devices such as a corona charger in which ozone is generated, a developing apparatus where scattered toner is formed, a fixing unit or a power supply being heated to a high temperature, and allows air current generated by the fan to pass therethrough. Air current noise that is generated by the operation of the fan is an annoying noise for users. Hitherto, JP H08- 156 367 A has proposed reducing of air current noise, for example, by providing a plurality of ducts having different lengths or by providing a hollow tubular side branch having a closed first end to the duct and causing air noise passing therethrough to interfere with one another. US 2005/161280 A1 discloses a silencer that includes a housing having a flat enclosing shape and having formed therein a passage for silencing; and pores, being formed at the housing so as to be communicatively connected with the passage, into which a sound wave to be noise is introduced. The pores, being formed close to the periphery of the housing, are configured so that the sound wave travels in the planar direction of the housing. WO 2021/261138 A1 discloses a silencer, which is provided in a duct in which a passage having an opening on both sides or one side is formed. The silencer is provided with: a case forming a space which communicates with the passage in the duct; and one or a plurality of dividing plates provided in the space inside the case. At least one of the dividing plates is provided in a position separated from at least a portion of a case inner wall positioned in a planar direction parallel to a boundary surface between the space inside the case and the passage inside the duct. However, further downsizing of the image forming apparatus is desired, and there is limited space within the image forming apparatus for installing fans and ducts. Therefore, it was difficult to adopt multiple ducts having different lengths or ducts with a side branch as described above to reduce the air current noise by causing interference of noises. It is an object of the invention to further downsize an image forming apparatus according to the preamble of claim 1. SUMMARY OF THE INVENTION This object is achieved by an image forming apparatus having the features of claim 1. Advantageous further developments are defined in the dependent claims. Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic drawing illustrating an image forming apparatus capable of adopting a blowing apparatus according to a present embodiment.FIG. 2A is a cross-sectional view illustrating an image forming and transferring apparatus.FG. 2B is an enlarged view illustrating an image forming unit.FIG. 3 is a rear view illustrating an airflow unit.FIG. 4 is a block diagram illustrating one example of air flow rates of fans.FIG. 5A is a front view illustrating an external appearance of the image forming and transferring apparatus.FIG. 5B is a right side view illustrating the external appearance of the image forming and transferring apparatus.FIG. 6 is a perspective view illustrating a rear side of a duct unit.FIG. 7 is a perspective view illustrating a front side of the duct unit.FIG. 8 is a perspective view illustrating a fan and a noise reduction duct.FIG. 9 is a cross-sectional view illustrating the fan and the noise reduction duct.FIG. 10 is a perspective view illustrating the noise reduction duct having a noise absorption sheet attached thereto.FIG. 11 is a top view illustrating an attaching area of the noise absorption sheet on the noise reduction duct.FIG. 12 is a graph illustrating a level of air current noise of a case where a noise reduction duct is used and a case where a duct having no noise absorbing holes is used.FIG. 13 is a schematic diagram illustrating a duct with a side branch according to a conventional technique. DESCRIPTION OF THE EMBODIMENTS Image Forming System The present embodiment will be described below. At first, an image forming apparatus capable of adopting a blowing apparatus according to the present embodiment will be described with reference to FIGs. 1 to 2B. An image forming system 1X illustrated in FIG. 1 incl