US-20260126752-A1 - IMAGE CARRYING MEMBER UNIT AND IMAGE FORMING APPARATUS THEREWITH

Abstract

An image carrying member unit includes an image carrying member and a cleaning device. The cleaning device has a cleaning blade that makes line contact with the outer circumferential surface of the image carrying member under a predetermined pressure and that is formed of an elastic material in the shape of a rectangular parallelepiped and scraping off residual toner on the image carrying member, and a supporting member to which the cleaning blade is fixed in a state projecting upstream in the rotational direction of the image carrying member. When the free length over which the cleaning blade projects from the support member is L [mm], the thickness of the cleaning blade is t [mm], and the contact pressure of the cleaning blade against the image carrying member is W [gf/cm], then 7.5*(L/t)−23.9≤W≤24 and 12≤W.

Inventors

• Keiya NISHIMURA

Assignees

• KYOCERA DOCUMENT SOLUTIONS INC.

Dates

Publication Date

20260507

Application Date

20251103

Priority Date

20241107

Claims (3)

1. 1 . An image carrying member unit, comprising: an image carrying member that is rotatable, the image carrying member having a toner image formed on an outer circumferential surface thereof, and a cleaning device including: a cleaning blade that makes line contact with the outer circumferential surface of the image carrying member under a predetermined pressure, the cleaning blade being formed of an elastic material in a shape of a rectangular parallelepiped and scraping off residual toner on the image carrying member, and a supporting member to which the cleaning blade is fixed in a state projecting upstream in a rotational direction of the image carrying member, wherein when a free length over which the cleaning blade projects from the support member is L [mm], a thickness of the cleaning blade is t [mm], and a contact pressure of the cleaning blade against the image carrying member is W [gf/cm], then Formulas (1) and (2) below are satisfied. 7.5 * ( L / t ) - 23.9 ≤ W ≤ 24 ( 1 ) 12 ≤ W ( 2 )
2. 2 . The image carrying member unit, according to claim 1 , wherein a ratio L/t of the free length L [mm] to the thickness t [mm] satisfies Formula (3) below. 4 . 5 ≤ L / t ≤ 5.3 ( 3 )
3. 3 . An image forming apparatus, comprising: the image carrying member unit according to claim 1 .

Description

INCORPORATION BY REFERENCE This application is based on and claims the benefit of priority from Japanese Patent Application No. 2024-194956 filed on Nov. 7, 2024, the contents of which are hereby incorporated by reference. BACKGROUND The present disclosure relates to an electrophotographic image forming apparatuses such as copiers, printers, and facsimile machines as well as multifunction peripherals having their functions integrated together. More particularly, the present disclosure relates to an image carrying member unit including an image carrying member and a cleaning device having a cleaning blade for removing residual toner on the image carrying member, and to an image forming apparatus provided with such an image carrying member unit. Conventional image forming apparatuses typically use powder developer and commonly employ a process is which, using a development device, an electrostatic latent image formed on an image carrying member such as a photosensitive drum is made visible with toner in the developer and the visible image (toner image) is transferred to a recording medium and is then subjected to fixing. The toner remaining on the surface of the photosensitive drum is removed by a cleaning device having a cleaning blade that is kept in pressed contact with the photosensitive drum and then a new toner image is formed. Today, toner with a small particle size and high sphericity is used, resulting in increased adhesion of the toner to the photosensitive drum. Thus, it is necessary to increase the contact pressure of the cleaning blade to effectively remove toner remaining on the surface of the photosensitive drum. Inconveniently, increasing the contact pressure of the cleaning blade reduces the slipperiness of the surface of the photosensitive drum, particularly its slipperiness with the cleaning blade. This tends to cause squeaking (chattering) and twisting of the cleaning blade and chipping of an edge part of the cleaning blade. Using toner with a small particle size and high sphericity also tends to cause cleaning faults due to the toner, toner external additive, or the like adhered to the surface of the photosensitive drum slipping across an edge part of the cleaning blade. When the edge part of the cleaning blade wears or chips off through repeated use, cleaning faults are likely. SUMMARY According to one aspect of the present disclosure, an image carrying member unit includes an image carrying member and a cleaning device. The image carrying member is rotatable and has a toner image formed on its outer circumferential surface. The cleaning device has a cleaning blade that makes line contact with the outer circumferential surface of the image carrying member under a predetermined pressure and that is formed of an elastic material in the shape of a rectangular parallelepiped and scraping off residual toner on the image carrying member, and a supporting member to which the cleaning blade is fixed in a state projecting upstream in the rotational direction of the image carrying member. When the free length over which the cleaning blade projects from the support member is L [mm], the thickness of the cleaning blade is t [mm], and the contact pressure of the cleaning blade against the image carrying member is W [gf/cm], then Formulas (1) and (2) below are satisfied 7.5*(L/t)-23.9≤W≤24(1)12≤W(2) BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing the overall structure of an image forming apparatus including drum units according to the present disclosure. FIG. 2 is a side sectional view showing the configuration of a drum unit according to one embodiment of the present disclosure and around a toner conveyance device coupled to it. FIG. 3 is a perspective view of a cleaning blade and a support member used in the drum units according to the embodiment. FIG. 4 is an enlarged perspective view around end parts of the cleaning blade and the support member in FIG. 3. FIG. 5 is an enlarged view of a contact part between the cleaning blade and photosensitive drums in FIG. 2. FIG. 6 is a conceptual diagram illustrating the chipping of an edge part of the cleaning blade. FIG. 7 is a conceptual diagram showing the variation of the dynamic linear pressure of the cleaning blade observed when the photosensitive drums are driven to rotate. FIG. 8 is a graph showing the designable region of the cleaning blade used in the drum units according to the embodiment. FIG. 9 is a graph showing the relationship between the tolerable range of contact pressure fluctuation and the tolerance range of the cleaning blade. FIG. 10 is a graph showing the relationship between L/t and the contact pressure W of the drum units in examples along with the results of evaluation of squeaking and twisting of the cleaning blade and chipping of the edge part and cleaning faults. DETAILED DESCRIPTION [1. Configuration of Image Forming Apparatus] An embodiment of the present disclosure will be described below with ref