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CN-122018269-A - Developing unit

CN122018269ACN 122018269 ACN122018269 ACN 122018269ACN-122018269-A

Abstract

A developing unit includes a developer container, a rotatable developing member, a magnet provided inside the rotatable developing member, and a conduit portion including a suction port, a first conduit wall, and a second conduit wall. P1 is downstream of P2 and upstream of P3. P1 is a point at which a line connecting the rotation center of the rotatable developing member and the distal end of the first conduit wall intersects the outer peripheral surface of the rotatable developing member. Fθ+.0 is satisfied in the range from P1 to P3 in the rotation direction of the rotatable developing member. Fθ is a magnetic force in a tangential direction with respect to the outer peripheral surface of the rotatable developing member among magnetic forces acting on the carrier on the outer peripheral surface of the rotatable developing member.

Inventors

  • OKUBO YUJI

Assignees

  • 佳能株式会社

Dates

Publication Date
20260512
Application Date
20251110
Priority Date
20241111

Claims (15)

  1. 1. A developing unit comprising: A developer container configured to contain a developer including a toner and a carrier; A rotatable developing member configured to carry a developer and feed the developer to a developing position in which an electrostatic latent image formed on the image bearing member is developed; a regulating portion configured to regulate an amount of developer carried on an outer peripheral surface of the rotatable developing member; a magnet non-rotatably and fixedly disposed inside the rotatable developing member, the magnet comprising: A regulating pole disposed to face the regulating portion; a first feed pole provided downstream of the regulating pole in a rotation direction of the rotatable developing member; A second feeding pole disposed adjacent to the first feeding pole and downstream of the first feeding pole in a rotation direction of the rotatable developing member and having a polarity different from that of the first feeding pole, and A developing pole disposed downstream of the second feeding pole in a rotation direction of the rotatable developing member and facing the image bearing member at the developing position, and A conduit portion, the conduit portion comprising: a suction port that is an inlet through which the developer scattered in the developer container is sucked, and extends from the suction port upstream in the rotational direction of the rotatable developing member; a first conduit wall disposed to face the rotatable developing member, and A second duct wall provided to face the rotatable developing member and to face the first duct wall, and configured to form a space between the second duct wall and the first duct wall through which developer sucked from the suction port flows, the second duct wall being located outside the first duct wall with respect to a rotation center of the rotatable developing member in a radial direction of the rotatable developing member, Wherein the suction port is located upstream of a point on the outer circumferential surface of the rotatable developing member at which an absolute value of a magnetic flux density of the developing pole in a normal direction with respect to the outer circumferential surface of the rotatable developing member becomes maximum, and downstream of a point on the outer circumferential surface of the rotatable developing member at which an absolute value of a magnetic flux density of the regulating pole in a normal direction with respect to the outer circumferential surface of the rotatable developing member becomes maximum, In the rotational direction of the rotatable developing member, P1 is located downstream of P2 and upstream of P3, wherein, P1 is a point at which a line connecting the rotation center of the rotatable developing member and the distal end of the first conduit wall on the suction port side intersects with the outer peripheral surface of the rotatable developing member, P2 is a point on the outer peripheral surface of the rotatable developing member at which the absolute value of the magnetic flux density of the first feeding electrode in the normal direction with respect to the outer peripheral surface of the rotatable developing member becomes maximum, and P3 is a point on the outer peripheral surface of the rotatable developing member at which the absolute value of the magnetic flux density of the second feeding electrode in the normal direction with respect to the outer peripheral surface of the rotatable developing member becomes maximum, and Wherein, the Fθ≥0 is satisfied in a range from P1 to P3 in a rotation direction of the rotatable developing member, wherein, Fθ is a magnetic force in a tangential direction with respect to an outer peripheral surface of the rotatable developing member among magnetic forces acting on the carrier on the outer peripheral surface of the rotatable developing member, and The direction of fθ from P1 toward P3 in the rotational direction of the rotatable developing member is defined as the positive direction.
  2. 2. The developing unit according to claim 1, wherein, The circumferential length of the rotatable developing member in the range from P4 to P3 in the rotational direction of the rotatable developing member is 40% or more of the circumferential length of the rotatable developing member in the range from P1 to P3 in the rotational direction of the rotatable developing member, and P4 is a point on the side closer to P1 among points on the outer peripheral surface of the rotatable developing member at which the absolute value of the magnetic flux density of the second feeding electrode in the normal direction with respect to the outer peripheral surface of the rotatable developing member becomes half of the maximum value.
  3. 3. The developing unit according to claim 1, wherein, The circumferential length of the rotatable developing member in the range from P4 to P3 in the rotational direction of the rotatable developing member is half or more of the circumferential length of the rotatable developing member in the range from P1 to P3 in the rotational direction of the rotatable developing member, and P4 is a point on the side closer to P1 among points on the outer peripheral surface of the rotatable developing member at which the absolute value of the magnetic flux density of the second feeding electrode in the normal direction with respect to the outer peripheral surface of the rotatable developing member becomes half of the maximum value.
  4. 4. The developing unit according to claim 1, wherein, Satisfies (Bc+B2)/2 being larger than or equal to B1 being larger than Bc, wherein, Bc is the maximum value of the absolute value of the magnetic flux density of the regulating pole in the normal direction with respect to the outer peripheral surface of the rotatable developing member, B1 is the maximum value of the absolute value of the magnetic flux density of the first feed pole in the normal direction relative to the outer peripheral surface of the rotatable developing member, and B2 is the maximum value of the absolute value of the magnetic flux density of the second feed electrode in the normal direction with respect to the outer peripheral surface of the rotatable developing member, and Wherein, the The circumferential length of the rotatable developing member in the range from P4 to P3 in the rotational direction of the rotatable developing member is 1/4 or more of the circumferential length of the rotatable developing member in the range from P1 to P3 in the rotational direction of the rotatable developing member, wherein, P4 is a point on the outer peripheral surface of the rotatable developing member on the side closer to P1, at which the absolute value of the magnetic flux density of the second feeding electrode in the normal direction with respect to the outer peripheral surface of the rotatable developing member becomes a half value of the maximum value.
  5. 5. The developing unit according to claim 1 or 2, wherein, In the rotational direction of the rotatable developing member, P1 is located within a range in which an absolute value of a magnetic flux density of the first feed pole in a normal direction with respect to an outer peripheral surface of the rotatable developing member is greater than 0.
  6. 6. The developing unit according to claim 1 or 2, wherein, The point P1 is located on a side farther from the image bearing member than a vertical line G, which is a tangent line on a side closer to the image bearing member, of tangent lines in the vertical direction of the rotatable developing member.
  7. 7. The developing unit according to claim 1 or 2, wherein, The second conduit wall extends downstream of a distal end of the first conduit wall on the suction port side in a rotational direction of the rotatable developing member.
  8. 8. The developing unit according to claim 1 or 2, wherein, The image bearing member is configured to be rotatable, and Wherein a rotation direction of the rotatable developing member is opposite to a rotation direction of the image bearing member at a position where the rotatable developing member and the image bearing member face each other.
  9. 9. A developing unit comprising: A developer container configured to contain a developer including a toner and a carrier; A rotatable developing member configured to carry a developer and feed the developer to a developing position in which an electrostatic latent image formed on the image bearing member is developed; a regulating portion configured to regulate an amount of developer carried on an outer peripheral surface of the rotatable developing member; a magnet non-rotatably and fixedly disposed inside the rotatable developing member, the magnet comprising: A regulating pole disposed to face the regulating portion; a first feed pole provided downstream of the regulating pole in a rotation direction of the rotatable developing member; A second feeding pole disposed adjacent to the first feeding pole and downstream of the first feeding pole in a rotation direction of the rotatable developing member and having a polarity different from that of the first feeding pole, and A developing pole disposed downstream of the second feeding pole in a rotation direction of the rotatable developing member and facing the image bearing member at the developing position, and A conduit portion, the conduit portion comprising: a suction port that is an inlet through which the developer scattered in the developer container is sucked, and extends from the suction port upstream in the rotational direction of the rotatable developing member; a first conduit wall disposed to face the rotatable developing member, and A second duct wall provided to face the rotatable developing member and to face the first duct wall, and configured to form a space between the second duct wall and the first duct wall through which developer sucked from the suction port flows, the second duct wall being located outside the first duct wall with respect to a rotation center of the rotatable developing member in a radial direction of the rotatable developing member, Wherein the suction port is located upstream of a point on the outer circumferential surface of the rotatable developing member at which an absolute value of a magnetic flux density of the developing pole in a normal direction with respect to the outer circumferential surface of the rotatable developing member becomes maximum, and downstream of a point on the outer circumferential surface of the rotatable developing member at which an absolute value of a magnetic flux density of the regulating pole in a normal direction with respect to the outer circumferential surface of the rotatable developing member becomes maximum, Wherein P1 is located downstream of P2 and upstream of P3 in the rotational direction of the rotatable developing member, wherein, P1 is a point at which a line connecting the rotation center of the rotatable developing member and the distal end of the first conduit wall on the suction port side intersects with the outer peripheral surface of the rotatable developing member, P2 is a point on the outer peripheral surface of the rotatable developing member at which the absolute value of the magnetic flux density of the first feeding electrode in the normal direction with respect to the outer peripheral surface of the rotatable developing member becomes maximum, and P3 is a point on the outer peripheral surface of the rotatable developing member at which the absolute value of the magnetic flux density of the second feeding electrode in the normal direction with respect to the outer peripheral surface of the rotatable developing member becomes maximum, and Wherein (Bc+B2)/2 is more than or equal to B1> Bc, wherein, Bc is the maximum value of the absolute value of the magnetic flux density of the regulating pole in the normal direction with respect to the outer peripheral surface of the rotatable developing member, B1 is the maximum value of the absolute value of the magnetic flux density of the first feed pole in the normal direction relative to the outer peripheral surface of the rotatable developing member, and B2 is the maximum value of the absolute value of the magnetic flux density of the second feed electrode in the normal direction with respect to the outer peripheral surface of the rotatable developing member, and Wherein a circumferential length of the rotatable developing member in a range from P4 to P3 in a rotational direction of the rotatable developing member is 1/4 or more of a circumferential length of the rotatable developing member in a range from P1 to P3 in a rotational direction of the rotatable developing member, wherein, P4 is a point on the outer peripheral surface of the rotatable developing member on the side closer to P1, at which the absolute value of the magnetic flux density of the second feeding electrode in the normal direction with respect to the outer peripheral surface of the rotatable developing member becomes a half value of the maximum value.
  10. 10. The developing unit according to claim 9, wherein, The circumferential length of the rotatable developing member in the range from P4 to P3 in the rotational direction of the rotatable developing member is 40% or more of the circumferential length of the rotatable developing member in the range from P1 to P3 in the rotational direction of the rotatable developing member.
  11. 11. The developing unit according to claim 9, wherein, The circumferential length of the rotatable developing member in the range from P4 to P3 in the rotational direction of the rotatable developing member is one half or more of the circumferential length of the rotatable developing member in the range from P1 to P3 in the rotational direction of the rotatable developing member.
  12. 12. The developing unit according to claim 9 or 10, wherein, In the rotational direction of the rotatable developing member, P1 is located within a range in which an absolute value of a magnetic flux density of the first feed pole in a normal direction with respect to an outer peripheral surface of the rotatable developing member is greater than 0.
  13. 13. The developing unit according to claim 9 or 10, wherein, The point P1 is located on a side farther from the image bearing member than a vertical line G, which is a tangent line on a side closer to the image bearing member, of tangent lines in the vertical direction of the rotatable developing member.
  14. 14. The developing unit according to claim 9 or 10, wherein The second conduit wall extends downstream of a distal end of the first conduit wall on the suction port side in a rotational direction of the rotatable developing member.
  15. 15. The developing unit according to claim 9 or 10, Wherein the image bearing member is configured to be rotatable, and Wherein a rotation direction of the rotatable developing member is opposite to a rotation direction of the image bearing member at a position where the rotatable developing member and the image bearing member face each other.

Description

Developing unit Technical Field The present disclosure relates to a developing unit that develops an electrostatic latent image formed on an image bearing member using a developer. Background An image forming apparatus such as a copier, a printer, a facsimile machine, or a multifunction peripheral includes a developing unit that attaches a developer to an electrostatic latent image formed on a photosensitive drum and develops the electrostatic latent image into a toner image. As the developer, a two-component developer including a toner and a carrier is widely used. In the developing unit, the amount of developer carried on the developing sleeve is regulated by a regulating member, and thereafter, the developer fed to a developing area facing the photosensitive drum as the developing roller rotates is used to develop the electrostatic latent image on the photosensitive drum into a toner image in the developing area. Therefore, in the developing unit, when the developer is fed by the rotating developing sleeve, the toner may fly. When toner is scattered, the scattered toner is accumulated near the developing unit and the photosensitive drum. Thereafter, if the accumulated toner drops onto the developing sleeve or the photosensitive drum due to vibration during image formation or maintenance, image defects may occur. US 2021/0096500 A1 discloses a developing unit including a suction duct that sucks the scattered toner to collect the scattered toner and discharges the toner out of the developing unit. Here, in order for the suction duct to efficiently suck the scattered toner, it is desirable to dispose the suction port near the developing sleeve. In this arrangement, in the vicinity of the suction port, the air sucked into the duct reaches the surface of the developing sleeve and collides with the carrier carried on the surface of the developing sleeve. Due to the collision of air, the carrier may be separated from the developing sleeve, and may be sucked into the suction duct together with the scattered toner. When the carrier reaches the suction path of the suction duct, the carrier is deposited in the suction path, narrowing the cross-sectional area of the flow path, so that the desired air flow rate cannot be obtained. As a result, the scattered toner cannot be sufficiently sucked. In addition, in the case where a filter for collecting toner is installed in the suction duct path, the filter may be clogged by the carrier, thereby reducing the suction force, and scattered toner cannot be sufficiently sucked, which may cause a situation where image defects occur daily. The duct suction path is difficult to clean, which may cause a situation where scattered toner is not sufficiently sucked, and thus image failure occurs daily. US 2021/0096500 A1 discloses a configuration in which a recess is formed on the lower surface of the suction duct path, and a carrier is collected by the recess to prevent the carrier that has entered when the scattered toner is sucked through the suction duct from entering the main body. However, particularly under the use condition in which the image forming apparatus operates at a high speed, the amount of the carrier separated from the developing sleeve tends to increase, the concave portion may be filled with the carrier and the carrier may overflow from the concave portion. Then, the carrier overflowed from the concave portion enters the suction path and is deposited in the suction path, and the scattered toner cannot be sufficiently sucked, resulting in a case where image failure occurs daily. Disclosure of Invention One aspect of the present disclosure is to inhibit aspiration of a carrier into a catheter section. According to a first aspect of the present disclosure, a developing unit includes a developer container configured to contain developer including toner and carrier, a rotatable developing member configured to carry the developer and feed the developer to a developing position in which an electrostatic latent image formed on the image carrying member is developed, a regulating portion configured to regulate an amount of the developer carried on an outer peripheral surface of the rotatable developing member, a magnet non-rotatably and fixedly disposed inside the rotatable developing member, the magnet including a regulating pole disposed to face the regulating portion, a first feeding pole disposed downstream of the regulating pole in a rotation direction of the rotatable developing member, a second feeding pole disposed adjacent to the first feeding pole and disposed downstream of the first feeding pole in the rotation direction of the rotatable developing member, and having a polarity different from that of the first feeding pole, and a magnet non-rotatably and fixedly disposed inside the rotatable developing member, the magnet including a regulating pole disposed to face the regulating portion, a first feeding pole disposed downstream of the regulating pole in the rot