Charging device, cartridge for image forming apparatus, and image forming apparatus

1. A charging device comprising:

a first electrode;

a second electrode;

an insulating body that is provided between the first electrode and the second electrode;

wherein either the first electrode or the second electrode includes an opening portion that is formed so as to open toward a first direction in which the first electrode, the insulating body, and the second electrode are laminated,

the insulating body includes a region limiting portion which is a space that is in contact with the opening portion, and opens toward a direction in which the region limiting portion communicates with the opening portion, and is limited in a second direction vertical to the first direction; and

wherein a glow discharge occurs in the region limiting portion when a voltage is applied between the first electrode and the second electrode.

2. The charging device according to claim 1 ,

wherein a space including the opening portion and the region limiting portion is adjacent to the first electrode and the second electrode.

3. The charging device according to claim 1 ,

wherein at least one of the first electrode and the second electrode has a volume resistivity equal to or more than about 1×10 6 Ωcm and equal to or less than about 1×10 10 Ωcm.

4. The charging device according to claim 1 ,

wherein the region limiting portion has a length equal to or more than about 4 μm and equal to or less than about 200 μm.

5. The charging device according to claim 1 ,

wherein the length of the region limiting portion in the second direction is equal to or more than about 4 μm and equal to or less than about 200 μm.

6. The charging device according to claim 1 ,

wherein a space including the opening portion and the region limiting portion has a cylindrical shape.

7. The charging device according to claim 1 ,

wherein a plurality of spaces each including the opening portion and the region limiting portion are provided in the insulating body.

8. A cartridge for an image forming apparatus, comprising:

an image carrier;

a charging device that is arranged so as not to contact the image carrier and charges the image carrier, the charging device including a first electrode, a second electrode, an insulating body that is provided between the first electrode and the second electrode; wherein either the first electrode or the second electrode includes an opening portion that is formed so as to open toward a first direction in which the first electrode, the insulating body, and the second electrode are laminated, and the insulating body includes a region limiting portion which is a space that is in contact with the opening portion, and opens toward a direction in which the region limiting portion communicates with the opening portion, and is limited in a second direction vertical to the first direction;

a developing device that develops a latent image, which is formed on the image carrier charged by the charging device by exposure, with a developer; and

wherein a glow discharge occurs in the region limiting portion when a voltage is applied between the first electrode and the second electrode.

9. An image forming apparatus comprising:

an image carrier;

a charging device that is arranged so as not to contact the image carrier and charges the image carrier, the charging device including a first electrode, a second electrode, an insulating body that is provided between the first electrode and the second electrode; wherein either the first electrode or the second electrode includes an opening portion that is formed so as to open toward a first direction in which the first electrode, the insulating body, and the second electrode are laminated, and the insulating body includes a region limiting portion which is a space that is in contact with the opening portion, and opens toward a direction in which the region limiting portion communicates with the opening portion, and is limited in a second direction vertical to the first direction;

a developing device that develops a latent image, which is formed on the image carrier charged by the charging device by exposure, with a developer;

a transfer unit that transfers an image developed by the developing device onto a recording medium;

a fixing unit that fixes the image transferred to the recording medium by the transfer unit to the recording medium; and

wherein a glow discharge occurs in the region limiting portion when a voltage is applied between the first electrode and the second electrode.

10. The charging device according to claim 1 , wherein the opening portion penetrates the first electrode or the second electrode towards the first direction.

11. The charging device according to claim 1 , wherein the region limiting portion limits a discharge region in the second direction vertical to the first direction.

12. The cartridge according to claim 8 , wherein the opening portion penetrates the first electrode or the second electrode towards the first direction.

13. The cartridge according to claim 8 , wherein the region limiting portion limits a discharge region in the second direction vertical to the first direction.

14. The image forming apparatus according to claim 9 , wherein the opening portion penetrates the first electrode or the second electrode towards the first direction.

15. The image forming apparatus according to claim 9 , wherein the region limiting portion limits a discharge region in the second direction vertical to the first direction.