1. Field of the Invention
The present general inventive concept relates to an image drum to selectively adsorb toner to form an image, and more particularly, to an image drum which provides a simpler fabrication process, a reduced unit price and an increased productivity, and a fabricating method thereof.
2. Description of the Related Art
FIG. 1 is a side view of an image forming apparatus employing a conventional image drum therein, FIG. 2 is a perspective view of a conventional image drum, and FIG. 3 is a cross-section view of a part of the image drum of FIG. 2.
Referring to FIG. 1, an image forming apparatus includes a toner feed part 40, an image drum 10 to adsorb toner 1 off of the toner feed part 40 by using an electrostatic force, a magnetic cutter 50 to disengage some of the toner 1 from the image drum 10, and a toner recovery part 60 to recover the toner 1, which has been disengaged from the image drum 10, back into the toner feed part 40.
Specifically, part of the toner 1, which is fed from the toner feed part 40 to the image drum 10, is disengaged from the image drum 10 by the magnetic cutter 50, and the remaining toner 1 on the image drum 10 is transferred via an image transfer part 70 and fixed onto a printing paper. As a result, an image is printed onto the printing paper.
Referring to FIGS. 2 and 3, an image drum 10 generally includes a cylindrical drum body 12. The cylindrical drum body 12 is made out of a metal such as aluminum or an aluminum alloy. A plurality of ring electrodes 14 are formed circumferentially on an outer surface of the cylindrical drum body 12. Each of the ring electrodes 14 is covered with a thin insulating layer in order to be kept electrically nonconductive from the cylindrical drum body 12 and other electrodes. The ring electrodes 14 are provided in various arrangements according to a desired resolution. For example, the ring electrodes 14 are formed on the cylindrical drum body 12 rather densely, that is, at pitches of approximately 40 μm in order to realize a resolution of 600 dpi.
A printed circuit board (PCB) 16 including a control chip is mounted in the cylindrical drum body 12, in which a terminal 18 is formed on a side to contact the cylindrical drum body 12. The PCB 16 may apply a high voltage to the ring electrodes 14 through the terminal 18. Referring to FIG. 3, a conductive material 32 is charged in holes 24 and 26 of the ring electrodes 14. The conductive material 32 is electrically connected to a zebra-strip 36. A silicon dioxide film 34 is formed on the inner wall of the holes 24 and 26 in order to insulate the cylindrical drum body 12 and the ring electrodes 14 from each other.
In order to fabricate a conventional image drum 10, a plurality of holes with a width of 20 μm are first formed at the intervals of approximately 40 μm in a surface of the cylindrical drum body 12 by using a diamond cutting device. A laser beam or an electric beam may be used to form the holes with a width of 20 μm along a circumference of the cylindrical drum body 12.
Next, holes are pierced through the cylindrical drum body 12 using a laser beam, each having a larger-diameter hole 26 formed from within the cylindrical drum body 12 and a smaller-diameter hole 24 formed from an internal surface or an external surface of the cylindrical drum body 12. Next, an insulating layer such as a silicon dioxide film 34 is formed over the cylindrical drum body 12 and the holes 24 and 26 in order to form the ring electrodes 14, and the piercing holes 24 and 26 are filled with a conductive material 32. The outer surface of the cylindrical drum body 12 is removed to a predetermined depth by polishing in order to form the ring electrodes 14 and electric connecting parts within the piercing holes 24 and 26. An insulating layer is then formed on the surface of the cylindrical drum body 12, and the PCB 16 is mounted.
As explained above, it takes a considerably complicated process to form the ring electrodes 14 on the surface of the cylindrical drum body 12, which includes forming densely spaced holes with a precision cutting device, forming piercing holes in the cylindrical drum body 12, forming a silicon dioxide film 34, and charging the piercing holes with a conductive material 32. In particular, the process of drilling holes and charging the holes with the conductive material 32 in order to connect the ring electrodes 14 with the terminal 18 of the PCB 16 takes a considerable amount of time and is also costly.