Magnet including a non-rotatable shaft engaged with a through hole at a lateral end

1 . A developing device, the developing device comprising:

a developing roller configured to bear a developer, the developing roller including a magnet including a plurality of magnetic poles arranged in a circumferential direction of the magnet;

a developer supplying rotator disposed opposite the developing roller, the developer supplying rotator configured to rotate in a predetermined direction to supply the developer onto the developing roller;

a compartment accommodating the developer supplying rotator;

a first developing side plate including a through hole configured to position the magnet in the circumferential direction of the magnet;

a seal mounted on the first developing side plate;

a second developing side plate supporting the developer supplying rotator rotatably; and

a sheet member configured to separate the developing roller from the developer supplying rotator, the sheet member configured to form an enclosed space that contains the developer in the compartment, the sheet member configured to be removed from the developing device,

wherein the first developing side plate includes a sheet opening disposed opposite the second developing side plate, the sheet opening through which a part of the sheet member protrudes toward an outside of the developing device,

wherein the magnet includes a non-rotatable shaft,

wherein the non-rotatable shaft is disposed at a lateral end of the magnet and the non-rotatable shaft is engaged with the through hole, and

wherein the seal is mounted on the sheet opening of the first developing side plate and the seal presses against the second developing side plate.

2 . The developing device according to claim 1 , wherein the seal is configured to seal the sheet opening before and after the sheet member is removed from the developing device.

3 . The developing device according to claim 1 ,

wherein the sheet opening includes a recess disposed opposite the second developing side plate.

4 . The developing device according to claim 1 , further comprising a cushioning member interposed between the first developing side plate and the second developing side plate.

5 . The developing device according to claim 4 ,

wherein the cushioning member includes a urethan sheet.

6 . The developing device according to claim 1 ,

wherein the developer supplying rotator includes a first conveying screw including:

a rotation shaft; and

a screw portion wound around the rotation shaft, and

wherein the first conveying screw conveys the developer in an axial direction of the first conveying screw.

7 . The developing device according to claim 6 , further comprising:

a second conveying screw disposed below the first conveying screw;

a wall via which the second conveying screw is disposed opposite the first conveying screw; and

a circulation path formed by the first conveying screw and the second conveying screw, the circulation path through which the developer circulates.

8 . The developing device according to claim 7 , further comprising:

a lower developing case supporting the first conveying screw and the second conveying screw rotatably, the lower developing case combined with the second developing side plate; and

an upper developing case covering the developing roller, the upper developing case combined with the lower developing case.

9 . The developing device according to claim 8 ,

wherein the lower developing case includes a mount attached with the sheet member.

10 . The developing device according to claim 8 , further comprising a mount attached with the sheet member, the mount configured to be separated from the lower developing case.

11 . The developing device according to claim 1 , further comprising:

a first gear;

an idler gear meshing with the first gear; and

a second gear meshing with the idler gear,

wherein the developing roller includes a rotation shaft mounting the first gear, and

wherein the developer supplying rotator includes a rotation shaft mounting the second gear.

12 . The developing device according to claim 11 ,

wherein on a cross section perpendicular to an axial direction of the rotation shaft of one of the developing roller and the developer supplying rotator, the sheet member is disposed in a space enclosed by the first gear, the second gear, and the idler gear.

13 . The developing device according to claim 11 ,

wherein an outer diameter of the idler gear is smaller than an outer diameter of each of the first gear and the second gear.

14 . The developing device according to claim 1 ,

wherein the sheet member includes a sheet made of a transparent resin material.

15 . A process cartridge comprising:

an image bearer configured to bear a latent image; and

a developing device combined with the image bearer into a unit, the developing device configured to contain a developer,

the developing device comprising:

a developing roller configured to bear the developer and the developing roller including a magnet including a plurality of magnetic poles arranged in a circumferential direction of the magnet;

a developer supplying rotator disposed opposite the developing roller, the developer supplying rotator configured to rotate in a predetermined direction to supply the developer onto the developing roller;

a compartment accommodating the developer supplying rotator;

a first developing side plate including a through hole configured to position the magnet in the circumferential direction of the magnet;

a seal mounted on the first developing side plate;

a second developing side plate supporting the developer supplying rotator rotatably; and

a sheet member configured to separate the developing roller from the developer supplying rotator, the sheet member configured to form an enclosed space that contains the developer in the compartment, the sheet member configured to be removed from the developing device,

wherein the first developing side plate includes a sheet opening disposed opposite the second developing side plate, the sheet opening through which a part of the sheet member protrudes toward an outside of the developing device,

wherein the magnet includes a non-rotatable shaft,

wherein the non-rotatable shaft is disposed at a lateral end of the magnet and the non-rotatable shaft engaged the through hole, and

wherein the seal is mounted on the sheet opening of the first developing side plate and the seal presses against the second developing side plate.

16 . An image forming apparatus comprising:

an image bearer configured to bear a latent image; and

a developing device configured to be removed from the image forming apparatus, the developing device configured to contain a developer,

the developing device including:

a developing roller configured to develop the latent image formed on the image bearer with the developer and the developing roller including a magnet including a plurality of magnetic poles arranged in a circumferential direction of the magnet;

a developer supplying rotator disposed opposite the developing roller, the developer supplying rotator configured to rotate in a predetermined direction configured to supply the developer onto the developing roller;

a compartment accommodating the developer supplying rotator;

a first developing side plate including a through hole configured to position the magnet in the circumferential direction of the magnet;

a seal mounted on the first developing side plate;

a second developing side plate supporting the developer supplying rotator rotatably; and

a sheet member configured to separate the developing roller from the developer supplying rotator, the sheet member configured to form an enclosed space that contains the developer in the compartment, the sheet member configured to be removed from the developing device,

a seal mounted on the first developing side plate,

wherein the first developing side plate includes a sheet opening disposed opposite the second developing side plate, the sheet opening through which a part of the sheet member protrudes toward an outside of the developing device,

wherein the magnet includes a non-rotatable shaft,

wherein the non-rotatable shaft is disposed at a lateral end of the magnet and is engaged the through hole, and

wherein the seal is mounted on the sheet opening of the first developing side plate and the seal presses against the second developing side plate.

17 . The developing device according to claim 1 ,

wherein the first developing side plate has a bottom face and a side face,

wherein the sheet opening is recessed from the bottom face, and

wherein the side face includes the through hole.