BRIEF DESCRIPTION OF THE DRAWINGS
These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIGS. 1A and 1B are a perspective view and a partially magnified cross-sectional view of a section of a conventional developer;
FIGS. 2A and 2B are a perspective view and a partially magnified cross-sectional view of a section of a developer agitator according to an embodiment of the present invention;
FIGS. 2C and 2D are partially magnified cross-sectional views of a developer agitator according to another embodiment of the present invention;
FIG. 3 is a perspective view exemplifying a section of a developer agitator according to another embodiment of the present invention;
FIG. 4 is a perspective view showing a developing apparatus to which the developer agitator according to an embodiment of the present invention has been applied;
FIG. 5 is a graph showing developer electrification by a developer agitator in an embodiment of the present invention and by the conventional developer agitator shown in FIGS. 1A and 1B; and
FIG. 6 is a cross-sectional view showing an example image forming device to which the developing apparatus of FIG. 4 is applied.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.
An embodiment of the present invention is illustrated in FIGS. 2A and 2B: a developer agitator 40 includes a rotatable shaft 41, an agitating wing 42 disposed in the form of a helix on the circumferential surface of the shaft 41, and an uneven part 43 formed on a surface of the agitating wing 42.
The agitator 40 constructed as described above can be used for electrifying a developer by friction in, for example, a developing apparatus 100 as illustrated in FIG. 4. In this case, the uneven part 43 formed on the surface of the agitating wing 42 increases the contact area for the developer, and thus improves the electrification rate of the developer.
That is, the conventional agitating wing 3 (see FIGS. 1A and 1B) has a smooth surface, but the agitating wing 42 of the developer agitator 40 according to the embodiment of the present invention has the uneven part 43 formed on the surface thereof, thereby allowing a surface area of the agitating wing 42 to be enlarged compared with the conventional agitating wing 3. Accordingly, the contact area of the agitating wing 42 and the developer is increased, and thus without the requirement to quickly rotate the agitating wing 42 or increase the diameter thereof, the contact time between toner particles and, in a two component system developer, carrier particles of the developer, is lengthened and the number of particles contacted thereby is increased, increasing the electrification rate of the developer.
The uneven part 43 as described above can have a waved structure or a stepped structure, as illustrated by 53 and 63 in FIGS. 2C and 2D, respectively. Besides the waved structure or the stepped structure, the uneven part 43 can be configured in any combination of both waved and stepped structures that is capable of increasing the surface area thereof, an embodiment being the uneven part 43 shown in FIG. 2B. In one aspect of the present invention, the uneven part 43 has the same structure and cross-section along the entire length of the agitator 40. In another aspect of the present invention, the uneven part 43 can vary along the length of the agitator 40.
FIG. 3 is a perspective view exemplifying a section of a developer agitator 40′ according to another embodiment of the present invention. As illustrated in the drawing, the developer agitator 40′ has the same basic structure as that of the developer agitator 40 of the embodiment as described above and shown in FIG. 2A, which includes a rotatable shaft 41, an agitating wing 42 disposed in the formed of a helix on a circumferential surface of the shaft 41, and an uneven part 43 formed on a surface of the agitating wing 42. However, in the embodiment of the present invention shown in FIG. 3, the orientation of the uneven part 43′ is different from that of the uneven part 43 shown in FIG. 2A. That is, in the embodiment shown in FIG. 3, the uneven part 43′ is oriented in the longitudinal direction of the agitating wing 42′, whereas in the previous embodiment shown in FIG. 2A, the uneven part 43 is oriented in the transverse direction of the agitating wing 42.
Thus, in the embodiment of the present invention shown in FIG. 3, the surface area of the agitating wing 42′ is also enlarged, so that the developer agitator 40′ can obtain the same results as that of the agitator 40 in the previous embodiment shown in FIG. 2A. The formed orientation of the uneven part 43 is not limited to the examples illustrated in the drawings. For instance, the uneven part 43 can be formed in any other structure, for example, a slightly slanted structure that is capable increasing the surface area of the agitating wing 42.
FIG. 4 is a perspective view schematically exemplifying a developing apparatus 100 to which the developer agitator 40, according to the embodiment of the present invention as described above and shown in FIG. 2A, is applied. As shown in FIG. 4, the developing apparatus 100 includes a developing casing 110 having a developer-containing space formed in a predetermined shape. The developing casing 110 is provided with a developer inlet and a developer outlet. A developer cartridge 120 is connected to the developer inlet, and a developing roller 130 and a developer supplying roller 140 are rotatably disposed at the developer outlet.
The developer agitator 40 includes a first developer agitator 410 and a second developer agitator 420, which are rotatably disposed in the developer-containing space of the developing casing 110. A developer contained in the developer-containing space is agitated by the first and second developer agitators 410 and 420, so that the developer is electrified by friction. Because the agitating wings 42 of the developer agitators 410 and 420 have the contact areas for the developer enlarged by the uneven parts 43 formed on the surfaces thereof, the electrification rate of the developer is higher than if an agitator 1 with a smooth agitating wing 2 as shown in FIG. 1A was used,
FIG. 5 is a graph exemplifying the toner-electrification amount is compared to agitating time using the developer agitator according to an embodiment of the present invention. Referring to FIG. 5, by using the developer agitator according to an embodiment of the present invention, the toner-electrification amount was saturated in a shorter time compared to using a conventional developer agitator. In an image forming device, to form an acceptable developer image the toner-electrification amount should be at least 70% of a saturated state. In FIG. 5, a reference E indicates a suitable development image point. In the developer agitator of the embodiment of the present invention, the toner-electrification amount has reached the required value before the suitable development image point E, so that the developer agitator of the embodiment of the present invention can be used in high speed printing with a shorter development image point E.
FIG. 6 is a cross sectional view showing a section of an example image forming device to which the developing apparatus 100 of FIG. 4 as described above is applied. Referring to the drawing, a photoconductor 200 is disposed to face the developing roller 130 of the developing apparatus 100. A charging roller 210 is rotatably disposed in contact with the photoconductor 200 to charge the photoconductor 200. A scanning unit 220, using a light source such as a laser or light emitting diode (LED), scans a beam onto a surface of the photoconductor 200 electrified by the charging roller 210, and thus forms a predetermined electrostatic latent image on the surface of the photoconductor 200.
The electrostatic latent image of the photoconductor 200 is developed into a developer image by the developing apparatus 100, and the developer image is transferred onto a printing medium P, such as paper, transparency, etc., which is conveyed between a transferring roller 230 and the photoconductor 200. The developer image transferred onto the printing medium P is fixed on the printing medium P when it passes through a fusing apparatus 240.
The image forming process as described above is the same as that of the conventional image forming device, except that by using the agitator 40 contained in the developer 100, the electrification rate of the developer is increased by the developer agitator 40 as described above, thereby allowing the image forming device to be adapted to use in high speed printing.
As is apparent from the forgoing description, according to the embodiments of the present invention, the developer agitator, and the developing apparatus and the image forming device having the same can not only smoothly agitate the developer, but also increase the electrification rate of the developer. Accordingly, the developer agitator 40, and the developing apparatus 100 and the image forming device having the same according to the embodiments of the present invention can obtain an electrification rate of the developer required for high speed printing, thereby allowing the image forming device to be operated at a high speed.
Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
Patent Application
20080050152
