US-12625460-B2 - Electrophotographic image forming apparatus and cartridge

US12625460B2US 12625460 B2US12625460 B2US 12625460B2US-12625460-B2

Abstract

A cartridge includes a photosensitive drum, a charging roller for charging the photosensitive drum, a first unit including the photosensitive drum and the charging roller, a developing roller for depositing toner onto the photosensitive drum, and a second unit including the developing roller and movable between a developing position in which the toner is capable of being deposited onto the photosensitive drum from the developing roller and a spaced position in which at least a part of the developing roller is spaced from the photosensitive drum. The cartridge also includes a first engaging portion included in the first unit, and a second engaging portion included in the second unit and engagable with the first engaging portion. A spacing force receiving portion is provided that capable of receiving a spacing force causing the second unit to move from the developing position to the spaced position.

Inventors

Yuichi Fukui
Shinjiro Toba
Takeo Kawanami
Shinichi Nishida
Yasuyuki Egami

Assignees

CANON KABUSHIKI KAISHA

Dates

Publication Date: 20260512
Application Date: 20240816
Priority Date: 20190318

Claims (18)

1 . A cartridge comprising: a photosensitive drum; a charging roller for charging the photosensitive drum; a first unit including the photosensitive drum and the charging roller; a developing roller for developing toner on the photosensitive drum; a second unit including the developing roller and movable between a developing position in which the developing roller is capable of developing a latent image on the photosensitive drum with the toner and a spaced position in which at least a part of the developing roller is spaced from the photosensitive drum; a first engaging portion included in the first unit; a second engaging portion included in the second unit and engagable with the first engaging portion; a spacing force receiving portion capable of receiving a spacing force causing the second unit to move from the developing position to the spaced position; and a contact force receiving portion capable of receiving a contact force causing the second unit to move from the spaced position to the developing position, wherein, in the state where the first engaging portion engages with the second engaging portion, the second unit is held in the spaced position, wherein, when the contact force receiving portion receives the contact force causing the second unit to move from the spaced position to the developing position, the second engaging portion is spaced from the first engaging portion by relative movement of the first engaging portion and the second engaging portion so that the second unit is permitted to move from the spaced position to the developing position, wherein, when the spacing force receiving portion receives the spacing force, the second engaging portion engages with the first engaging portion by relative movement of the first engaging portion and the second engaging portion so that the second unit is restricted to move from the space position to the developing position, and wherein, when a predetermined tangential line is tangential to a surface of the photosensitive drum at an intersection, which is more remote from a rotational center of the charging roller, of intersections between a line connecting a rotational center of the charging roller and a rotational center of the photosensitive drum and the surface of the photosensitive drum, as viewed along a direction of a rotational axis of the developing roller, and the cartridge is divided by the predetermined tangential line into sections, a predetermined section is a section in which the rotational center of the charging roller does not exist, and wherein, as viewed along the rotational axis of the developing roller when the second unit is in the spaced position, the spacing force receiving portion is in the predetermined section.
2 . A cartridge according to claim 1 , wherein, as viewed along the rotational axis of the developing roller when the second unit is in the space position, the contact force receiving portion is in the predetermined section.
3 . A cartridge according to claim 1 , further comprising a first frame supporting the photosensitive drum and a second frame supporting the developing roller.
4 . A cartridge according to claim 3 , wherein the second frame is rotatable relative to the first frame so that the second unit moves between the developing position and the spaced position.
5 . A cartridge according to claim 3 , further comprising a movable member movable relative to the first frame, wherein the movable member includes the spacing force receiving portion.
6 . A cartridge according to claim 5 , wherein the movable member is movable relative to the second frame.
7 . A cartridge according to claim 6 , wherein the movable member is movably supported by the second frame.
8 . A cartridge according to claim 5 , wherein the movable member includes the contact force receiving portion.
9 . A cartridge according to claim 1 , wherein the first engaging portion includes a claw engageable with the second engaging portion.
10 . A cartridge according to claim 1 , wherein the second engaging portion includes a claw engageable with the first engaging portion.
11 . A cartridge according to claim 1 , further comprising a second unit urging member for urging the second unit in a direction from the spaced position toward the developing position.
12 . A cartridge according to claim 11 , wherein the second unit urging member includes an elastic member.
13 . A cartridge according to claim 12 , wherein the elastic member includes a spring.
14 . A cartridge according to claim 1 , wherein, when the spacing force receiving portion receives the spacing force, the second engaging portion engages with the first engaging portion by deformation of the first engaging portion and/or the second engaging portion so that the second unit is restricted to move from the space position to the developing position.
15 . A cartridge according to claim 14 , wherein the first engaging portion and/or the second engaging portion deforms elastically.
16 . A cartridge according to claim 1 , wherein the contact force receiving portion is in the predetermined section.
17 . A cartridge according to claim 1 , wherein the second engaging portion is provided with a projection that projects toward the first engaging portion, and wherein, in the state where the first engaging portion engages with the projection of the second engaging portion, the second unit is held in the spaced position.
18 . A cartridge according to claim 17 , wherein the first engaging portion elastically deforms when the projection of the second engaging portion engages with the first engaging portion.

Description

TECHNICAL FIELD The disclosure relates to an electrophotographic image forming apparatus such as a copying machine or a printer which uses an electrophotographic process, and a cartridge which can be mounted to or dismounted from the electrophotographic image forming apparatus. Here, the electrophotographic image forming apparatus (hereinafter, also referred to as “image forming apparatus”) is an apparatus which forms an image on a sheet-like recording material such as paper using an electrophotographic image forming process. Examples of the image forming apparatus include a copying machine, a facsimile machine, a printer (laser beam printer, LED printer, and so on, a multifunction printer thereof, and the like). The cartridge is a unit which can be mounted to and dismounted from the image forming apparatus described above, and is a unit including a photosensitive member and/or a process means (a charging member, a developing member, a cleaning member, and so on, for example) which is actable on the photosensitive member. BACKGROUND OF INVENTION An image forming apparatus which uses an electrophotographic image forming process includes an image forming apparatus which forms an image by a contact developing method which forms an image by performing a developing process in a state in which a developing member (developing roller) is in contact with a photosensitive drum. In such an image forming apparatus, the developing roller is urged toward the photosensitive drum at a predetermined pressure, and is in contact with the surface of the photosensitive drum at a predetermined pressure, during the development process. In the case that a developing roller including an elastic layer on the surface is used, the following can be considered, for example. That is, if the period during which the image is not formed (the developing roller is not rotating) with the elastic layer kept in contact with the surface of the photosensitive drum is long, the elastic layer of the developing roller is may be deformed by the contact with the surface of the photosensitive drum. By this, image defects such as unintended unevenness of the developer image may occur when the developing process is performed. Further, as another example, when the developing roller is in contact with the photosensitive drum during the period when the developing process is not performed, the developer carried on the developing roller is unnecessarily deposited to the photosensitive drum, and such a developer is deposited on the recording material with the result of contamination of the recording material. This problem may occur irrespective of the provision of an elastic layer on the surface of the developing roller. Further, as another example, when the photosensitive drum and the developing roller are in contact with each other for a long period of time other than the period during which the developing process is performed, the photosensitive drum and the developing roller are rubbed against each other for a long period of time. Deterioration of the developing roller or the developer may be accelerated. This may occur with or without an elastic layer on the surface of the developing roller. In order to avoid the above-mentioned problem, JP-A-2007-213024 and JP-A-2014-67005 discloses an image forming apparatus and a cartridge having a structure for spacing a developing roller from a surface of a photosensitive drum during a period in which developing process is not performed. SUMMARY OF INVENTION Problem to be Solved However, there is still room for further improvement in the conventional techniques described in JP-A-2007-213024 and JP-A-2014-67005. Therefore, it is an object of the present disclosure to further develop the conventional technique. Means for Solving the Problem In order to achieve the above object, a typical structure of the invention according to the present application is a cartridge comprising a charging member for charging the photosensitive member; a first unit including the photosensitive member and the charging member; a developing member for depositing toner onto the photosensitive member; a second unit including the developing member and movable between a developing position in which the toner is capable of being deposited onto the photosensitive member from the developing member and a spaced position in which at least a part of the developing member is spaced from the photosensitive member; a holding portion movably supported by the first unit or the second unit and movable between a first position for stably holding the second unit in the spaced position by the first unit and a second position for stably holding a second unit in the developing position by the first unit; and a contact force receiving portion capable of receiving a contact force for moving the holding portion from the first position toward the second position to move the second unit to the developing position, when the second unit is in the spaced position, wherei