CHARGING DEVICE, PHOTOCONDUCTIVE DRUM UNIT, AND IMAGE FORMING DEVICE

Abstract

A photoconductive drum unit includes a frame, a photoconductive drum, and a scorotron charging unit. The charging unit includes a pair of mounting members, a discharging electrode filament, a shield casing, a grid, and a connecting member. The mounting members are mounted and fixed at both end portions of the frame. The discharging electrode filament extends between the mounting members in a tensioned state. The shield casing is supported by being connected between the mounting members and covers the discharging electrode filament. The grid extends between the mounting members in a tensioned state and is arranged in an opening of the shield casing. The connecting member connects the mounting members and the shield casing in a state in which a slight displacement is permitted between the mounting members and the shield casing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of an example of an image forming device including a photoconductive drum unit according to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view of the photoconductive drum unit.

FIG. 3 is a partial exploded perspective view illustrating a relationship of mounting members and a shield casing in a charging unit arranged in the photoconductive drum unit.

Claims

1. A charging device mounted on a frame, the charging device comprising: a pair of mounting members mounted and fixed on both end portions of the frame;a discharging electrode filament extending between the mounting members in a tensioned state;a shield casing arranged to cover the discharging electrode filament by being supported between the mounting members and connected with the mounting members;a grid extending between the mounting members in a tensioned state and arranged in an opening of the shield casing; andat least one connecting member arranged to connect the pair of the mounting members and the shield casing in a state in which a slight displacement between the mounting members and the shield casing is permitted.

2. The charging device according to claim 1, wherein the at least one connecting member includes a catching pin and a catching hole arranged on the mounting members and the shield casing to loosely connect with one another.

3. The charging device according to claim 2, further comprising a spring tensioning the grid in its longitudinal direction with respect to the mounting members.

4. The charging device according to claim 2, wherein the discharging electrode filament is a thin band-shaped metal plate including a plurality of electrodes.

5. The charging device according to claim 2, wherein the pair of the mounting members, the discharging electrode filament, the shield casing, and the grid are unitized so as to define a single unitary structural element.

6. The charging device according to claim 2, wherein a diameter of the catching hole is slightly larger than a diameter of the catching pin.

7. The charging device according to claim 2, wherein the catching hole is oval.

8. A photoconductive drum unit comprising: a frame;a photoconductive drum rotatably supported on the frame; anda charging unit arranged to face a surface of the photoconductive drum, and mounted and fixed at both end portions of the frame to be arranged along a longitudinal direction of the photoconductive drum; whereinthe charging unit includes: a pair of mounting members mounted and fixed on the end portions of the frame;a discharging electrode filament extending between the mounting members in a tensioned state;a shield casing arranged to cover the discharging electrode filament by being supported between the mounting members and connected with the mounting members;a grid extending between the mounting members in a tensioned state and arranged in an opening of the shield casing; andat least one connecting member arranged to connect the pair of the mounting members and the shield casing in a state in which a slight displacement between the mounting members and the shield casing is permitted.

9. The photoconductive drum unit according to claim 8, wherein the at least one connecting member includes a catching pin and a catching hole arranged on the mounting members and the shield casing to loosely connect with one another.

10. The photoconductive drum unit according to claim 9, further comprising a spring which tensions the grid in its longitudinal direction with respect to the mounting members.

11. The photoconductive drum unit according to claim 9, wherein the discharging electrode filament is a thin band-shaped metal plate including a plurality of needle-like electrodes.

12. The photoconductive drum unit according to claim 9, wherein the pair of the mounting members, the discharging electrode filament, the shield casing, and the grid are unitized so as to define a single unitary structural element.

13. The photoconductive drum unit according to claim 9, wherein a diameter of the catching hole is slightly larger than a diameter of the catching pin.

14. The photoconductive drum unit according to claim 9, wherein the catching hole is oval.

15. An image forming device comprising: a photoconductive drum unit including a photoconductive drum and a charging unit; anda developing device unit which includes a toner container and a developing roller; whereinthe photoconductive drum unit includes: a frame;the photoconductive drum rotatably supported on the frame; anda charging unit arranged to face a surface of the photoconductive drum, and mounted and fixed at both end portions of the frame to be arranged along a longitudinal direction of the photoconductive drum; whereinthe charging unit includes: a pair of mounting members mounted and fixed on the end portions of the frame;a discharging electrode filament extending between the mounting members in a tensioned state;a shield casing arranged to cover the discharging electrode filament by being supported between the mounting members and connected with the mounting members;a grid extending between the mounting members in a tensioned state and arranged in an opening of the shield casing; andat least one connecting member arranged to connect the pair of the mounting members and the shield casing in a state in which a slight displacement between the mounting members and the shield casing is permitted.

16. The image forming device according to claim 15, wherein the connecting member includes a catching pin and a catching hole arranged on the mounting members and the shield casing to loosely connect with one another.

17. The image forming device according to claim 16, further comprising a spring which tensions the grid in its longitudinal direction with respect to the mounting members.

18. The image forming device according to claim 16, wherein the discharging electrode filament is a thin band-shaped metal plate including a plurality of needle-like electrodes.

19. The image forming device according to claim 16, wherein the pair of the mounting members, the discharging electrode filament, the shield casing, and the grid are unitized so as to define a single unitary structural element.

20. The image forming device according to claim 16, wherein a diameter of the catching hole is slightly larger than a diameter of the catching pin.

21. The image forming device according to claim 16, wherein the catching hole is oval.