EP-4741943-A1 - IMAGE CARRYING MEMBER UNIT AND IMAGE FORMING APPARATUS THEREWITH

Abstract

An image carrying member unit (50a-50d) includes an image carrying member (1a-1d) and a cleaning device (23a-23d). The cleaning device (23a-23d) has a cleaning blade (53) that makes line contact with the outer circumferential surface of the image carrying member (1a-1d) 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 (1a-1d), and a supporting member (55) to which the cleaning blade (53) is fixed in a state projecting upstream in the rotational direction of the image carrying member (1a-1d). When the free length over which the cleaning blade (53) projects from the support member (55) is L [mm], the thickness of the cleaning blade (53) is t [mm], and the contact pressure of the cleaning blade (53) against the image carrying member (1a-1d) is W [gf/cm], then 7.5 * (L / t) - 23.9 ≤ W ≤ 24 and 12 ≤ W.

Inventors

• NISHIMURA, KEIYA

Assignees

• KYOCERA Document Solutions Inc.

Dates

Publication Date

20260513

Application Date

20251105

Claims (3)

1. An image carrying member unit (50a-50d), comprising: an image carrying member (1a-1d) that is rotatable, the image carrying member having a toner image formed on an outer circumferential surface thereof, and a cleaning device (23a-23d) including: a cleaning blade (53) that makes line contact with the outer circumferential surface of the image carrying member (1a-1d) 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 (1a-1d), and a supporting member (55) to which the cleaning blade (53) is fixed in a state projecting upstream in a rotational direction of the image carrying member (1a-1d), characterized in that when a free length over which the cleaning blade (53) projects from the support member (55) is L [mm], a thickness of the cleaning blade (53) is t [mm], and a contact pressure of the cleaning blade (53) against the image carrying member (1a01d) is W [gf/cm], then Formulas (1) and (2) below are satisfied. 7.5 * L / t − 23.9 ≤ W ≤ 24 12 ≤ W
2. The image carrying member unit (50a-50d) according to claim 1, characterized in that 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. An image forming apparatus, comprising: the image carrying member unit (50a-50d) according to claim 1 or 2.

Description

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 An object of the present disclosure is to provide an image carrying member unit that prevents chipping of an edge part of a cleaning blade and that eliminates cleaning faults even if the contact pressure of the cleaning blade varies due to dimension tolerances or durable printing, and to provide an image forming apparatus including such an image carrying member unit. 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 12≤W BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic sectional view showing the overall structure of an image forming apparatus 1 including drum units 50 according to the present disclosure.Fig. 2 is a side sectional view showing the configuration of a drum unit 50 according to one embodiment of the present disclosure and around a toner conveyance device 60 coupled to it.Fig. 3 is a perspective view of a cleaning blade 53 and a support member 55 used in the drum units 50 according to the embodiment.Fig. 4 is an enlarged perspective view around end parts of the cleaning blade 53 and the support member 55 in Fig. 3.Fig. 5 is an enlarged view of a contact part between the cleaning blade 53 and photosensitive drums 1a to 1d in Fig. 2.Fig. 6 is a conceptual diagram illustrating the chipping of an edge part 53a of the cleaning blade 53.Fig. 7 is a conceptual diagram showing the variation of the dynamic linear pressure of the cleaning blade 53 observed when the photosensitive drums 1a to 1d are driven to rotate.Fig. 8 is a graph showing the designable region of the cleaning blade 53 used in the drum units 50a to 50d 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 53.Fig. 10 is a graph showing the relationship between L/t and the contact pressure W of the drum units 40a in examples along with the results of evaluation of squeaking and twisting of