Patent Application
20070258741
The above and other objects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:
Throughout the drawings, the same reference numerals will be understood to refer to the same elements, features, and structures.
The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of exemplary embodiments of the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the exemplary embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness
Referring initially to
The heating roller 110 is a rigid pipe, such as an aluminum or steel pipe, with a heat source inside, and layers applied on the core pipe such as a rubber layer, or a paper release layer. The heating roller 110 is controlled to maintain the temperature around 180° C., and rotated by power received from a driving source.
The fusing belt assembly 120 includes a pressure roller 121, a separating roller 122 and a fusing belt 123, which are passively driven by the rotation of the heating roller 110. Although not illustrated, the fusing belt assembly 120 may be constructed so that one or both of the pressure roller 121 and/or the separating roller 122 are actively driven.
The pressure roller 121 includes a rigid pipe, which is made of a metal such as steel or the like, and an elastic rubber coating around the rigid pipe. A pressure roller supporting elastic element 141 is disposed at the axis of rotation of the pressure roller 121, and presses the pressure roller 121 into contact with the heating roller 110.
The separating roller 122 is made of a metal (such as steel) pipe and has a slip prevention element 200. The diameter of the slip prevention element 200 is approximately the same as that of the separating roller 122.
The separating roller 122 can be formed by a steel pipe. It can also use an elastic layer which is relatively more flexible than the pressure roller 121. A separating roller supporting elastic element 142 may be disposed on both ends of the axis of rotation of the separating roller 122 to press the separating roller 122 into contact with the heating roller 110.
The fusing belt 123 is an endless loop that rotates about an endless track around the pressure roller 121 and the separating roller 122. The fusing belt forms a wide nip with respect to the heating roller 110. The fusing belt 123 may include a base made of a high polymeric material such as polyimide (PI) and polyetheretherketone (PEEK); a layer made of metal such as nickel (Ni) and its alloy or stainless steel, aluminum and its alloy, copper and its alloy; and an elastic layer and a paper release layer additionally formed on the layer.
As will be discussed below, the slip prevention element 200 may have various configurations and may be provided at various locations.
According to a first exemplary embodiment of the present invention illustrated in
According to a second exemplary embodiment of the present invention illustrated in
According to a third exemplary embodiment of the present invention illustrated in
According to a fourth exemplary embodiment of the present invention illustrated in
According to a fifth exemplary embodiment of the present invention illustrated in
According to a sixth exemplary embodiment of the present invention illustrated in
The friction materials 210, 220, 230, 240, 250, 260 used in the various exemplary embodiments of the slip prevention element 200 may be one of a silicone rubber, a urethane, or an expandable polystyrene (EPS).
The width (LP′) of the pressure roller 121 or the width (LP) of the separating roller 122, or the width of the fusing belt 123 is preferably greater than that of the paper transferring path to prevent the slip prevention elements from overlapping the paper transferring path (i.e. wider than paper passing through the fusing unit). Alternatively, each of the pressure roller 121, separating roller 122 and the fusing belt 123 may have a wider width (LR′, LR) than that of the paper transferring path.
The elastic layer, such as silicone rubber, may be applied over the entire surface of the separating roller 122, instead of forming the slip prevention elements 200 on both ends of the separating roller 122 as described in the first and the second exemplary embodiments of the present invention. If the elastic layer is formed over the entire separating roller 122, the diameter of the inner part (e.g. the pipe) of the separating roller is smaller. Therefore the separating roller 122 may be bent easily. Accordingly, the separating roller 122 may be easily deformed when the pressure between the separating roller 122 and the heating roller 110 increases, and this may lead to a decrease in fusing efficiency at the center of a paper (P) passing through the fusing unit 100. Moreover, when the driving torque of the passive-driving fusing belt assembly 120 increases, as the fusing belt assembly can be interrupted by an increase in driving torque of the fusing belt assembly 120, which rotates vertically, in the same time, friction between the fusing belt 123 and the separating roller 122 can be excessive, so it can easily be worn away.
In the above described exemplary embodiments of the present invention, the slip prevention element 200 was formed on the pressure roller 121 or the separating roller 122 since these rollers are passively rotated (i.e. they are rotated due to the rotation of the heating roller 110). The slip prevention element 200 may be formed on the heating roller 110, if the fusing belt assembly 120 is actively driven. If the slip prevention element 200 is formed on the heating roller 110, it may also be formed on both sides of the separating roller 122 in the same configuration as in the previous exemplary embodiments.
The feeding unit 310 holds a stack of paper (P). Sheets of paper (P) from the stack of paper (P) are provided to the developing unit 330 and the image transfer unit 340 by the conveyer 320 and receive a toner image. The paper (P) bearing the toner image therein is fused by the heat and pressure from the fusing unit 100, and then discharged outside the image forming apparatus by the discharging unit 350.
As mentioned before, the fusing unit 100 includes the fusing belt assembly 120 including the heating roller 100, the pressure roller 121, the separating roller 122 having the slip prevention element 200, and the fusing belt 123.
The operation of the image forming apparatus according to exemplary embodiments of the present invention will now be described in detail. Since the techniques for forming a toner image are well known to those skilled in the relevant art, a detailed explanation of those operations will be omitted.
As shown in
To fuse the toner image (T), the temperature of the nip (N), that is, the temperature of the contact area between the heating roller 110 and the fusing belt assembly 120 of the fusing unit 100, has to be approximately 180° C. before the fusing process begins. The heating roller 110 rotates to move the paper to a paper distribution tray (not shown), and the fusing belt assembly 120 is passively driven by the rotation of the heating roller 110. To maintain the temperature of the heating roller 110, a sensor may be provided to measure the temperature of the heating roller 110.
Each of the pressure roller 121, separating roller 122, and the fusing belt 123 of the fusing belt assembly 120 is pressed against the heating roller 110, and in this way, a first nip and a second nip are formed between the pressure roller 121 and the heating roller 110, and between the fusing belt 123 and the heating roller 110, respectively.
Therefore, when the paper (P) bearing a toner image (T) is transferred to the fusing unit 100, the heating roller 110 and the fusing assembly 120 move the paper (P), and in this process, the toner image (T) is first fused by pressure between the heating roller 110 and the pressure roller 121 as the paper (P) is passed through the first nip, and completely fused as the paper (P) is passed through the second nip between the heating roller 110 and the fusing roller 123.
Meanwhile, at the connection between the separating roller 122 and the fusing belt 123, slip may occur because the separating roller 122 is made of metal such as a steel pipe. The slip may lead to an irregular rotating speed for the fusing belt 123. If the rotating speed of the fusing belt 123 becomes irregular, the fusing process may be degraded. To prevent this, the slip prevention element 200 is formed at the connection between the separating roller 122 and the fusing belt 123.
It should be noted that the connection between the fusing belt 123 and the slip prevention element 200 may be damaged by friction, and the lifespan of the fusing belt 123 can be shortened if the slip prevention element 200 protrudes from the separating roller 122, as the diameter of the slip prevention element 200 is larger than that of the separating roller 122. Furthermore, the image can be contaminated if the protrusions overlap the path of the paper bearing a toner image (T).
To prevent such image contamination, the slip prevention element 200 according to the exemplary embodiments of the present invention is formed on both sides of the separating roller 122 so as not to overlap the path of the paper bearing a toner image (T), as shown in
While the exemplary embodiments of the present invention have been described with respect to a slip prevention element 200 formed on the separating roller 122, the description is also applicable to the other exemplary embodiments. That is, the slip prevention element 200 can be formed at the pressure roller 121, or it can be formed at both the pressure roller 121 and the separating roller 122, or it can be formed on the inner surface 123a of the fusing belt 123.
With the fusing unit 100 as described above in the exemplary embodiments of the present invention, a wider nip (N) is formed than the nip in a conventional 2-roller type fusing unit. Therefore, the quality of printing is improved by the increased size of the nip and the concomitant increase in length of time a paper stays in the nip. Moreover, with an increased nip, the fusing temperature can be kept at a low temperature, thereby reducing the warm-up time.
Since the fusing belt assembly 120 may be passively driven by the movement of the heating roller 110, it does not require an extra driving source. That is, it can be implemented at a relatively low cost and in a simple structure.
According to exemplary embodiments of the present invention, the length of time a paper remains in the nip while passing through the nip is increased, and the temperature of the fusing unit can be decreased, which leads to a decrease in required time for warm-up as well as an improvement in the quality of printing. In addition, the fusing belt is passively driven by the rotation of the heating belt, and it can be implemented at a low cost because it does not need any extra driving force.
Moreover, by using a slip prevention element to prevent slip between the separating roller and the fusing belt, fusing errors caused by slip of the fusing belt is minimized.
Also, since the slip prevention element is disposed at the ends of the separating roller outside of the paper path, image contamination caused by the slip prevention element is minimized.
While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-40050 | May 2006 | KR | national |
