Patent Grant
7715772
This application claims the benefit of Korean Patent Application No. 2005-55362, filed Jun. 25, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
Aspects of the present invention relate to an image forming apparatus and a fuser therefor, and more particularly, to an image forming apparatus having a print media-releasing member for releasing a print medium from a heating roller, and a fuser for such an image forming apparatus.
2. Description of the Related Art
Here, the image forming unit 120 includes a developer 121 having a photosensitive drum 122 for forming a toner image on a print medium 1, a transfer roller 123 rotating correspondingly to the photosensitive drum 122 with the print medium 1 placed in-between, and a fuser 124 for fusing toner onto the print medium 1 having the toner image formed thereon.
The fuser 124 is composed of a heating roller 125 heating the print medium 1 being conveyed from the developer 121 and a press roller 126 pressing the print medium 1 towards the heating roller 125. The toner formed on the print medium 1 is melted by the heating roller 125 and pressed by the press roller 126 therebelow to thereby be fused on the surface of the print medium 1. The print medium 2 fused with the toner is conveyed to the print media-ejector 130 and discharged to the outside.
In the above conventional technique, however, the toner on the print medium 1 is in contact with and pressed on the heating roller 125, so that the toner is likely to attach to the surface of the heating roller 125 during the fusing process. In this case, the print medium 1 sticks to the surface of the heating roller 125 by means of the toner and then rotates together with the heating roller 125. Thus, the print medium 1 itself may be creased and consequently jammed inside the image forming apparatus 100.
Moreover, in a case where the surface layer of the heating roller 125 is formed of a resilient material such as rubber, the print medium 1 attached to the heating roller 125 must be separated therefrom, without damaging the heating roller 125.
Aspects of the present invention provide an image forming apparatus and a fuser therefor comprising a print roller having a resilient surface layer, in which a print medium attached to the print roller can be easily released therefrom without damaging the print roller.
According to an aspect of the present invention, there is provided an image forming apparatus having a print roller, in which a circumferential elastic contact part of the print roller contacts and presses a print medium to convey the print medium, the apparatus comprising: one or more push rollers pressing the print roller to elastically deform the circumferential elastic contact part; and one or more print media-releasing members comprising a claw member to be protruded into a space formed by the elastic deformation of the circumferential contact portion, the print medium being released from the print roller by use of the claw member.
The push roller may, although not necessarily, be provided on both sides of the print media-releasing member.
A rotating axis of the push roller may, although not necessarily, pass through the print media-releasing member.
The print media-releasing member may, although not necessarily, be provided with a rotation shaft where the push roller rotates.
The push roller may, although not necessarily, be provided with a rotation shaft which is formed to pass through the print media-releasing member.
The print roller may, although not necessarily, further comprise a central part having a predetermined radius, and the circumferential elastic contact part comprises a surface layer formed of an elastic material, the surface layer being formed in the circumferential face of the central part and having a predetermined thickness.
The print roller may, although not necessarily, comprise an elastic body.
The print roller may, although not necessarily, be a heating roller.
According to another aspect of the present invention, there is provided a fuser for an image forming apparatus comprising a heating roller having a circumferential elastic contact part and a heater generating heat by an electric power externally supplied, and a press roller conveying a print medium interposed in-between with the heating roller while contact-pressing the print medium towards the heating roller, the fuser comprising: one or more push rollers pressing the heating roller to elastically deform the circumferential elastic contact portion; and one or more print media-releasing members comprising a claw member to be protruded into a space formed by the elastic deformation of the circumferential contact portion, the print medium being released from the heating roller by means of the claw member.
Two push rollers may, although not necessarily, be provided on both sides of the print media-releasing member.
A rotating axis of the push roller may, although not necessarily, pass through the print media-releasing member.
The print media-releasing member may, although not necessarily, be provided with a rotation shaft where the push roller rotates.
The push roller may, although not necessarily, be provided with a rotation shaft which is formed to pass through the print media-releasing member.
The heating roller may, although not necessarily, further comprise a central part having a predetermined radius, and the circumferential elastic contact part comprises a surface layer formed of an elastic material, the surface layer being formed in the circumferential face of the central part and having a predetermined thickness.
The heating roller may, although not necessarily, comprise an elastic body.
Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
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 accompany drawings of which:
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 like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.
As shown in
Other types of print media 13 aside from paper, such as transparencies, overheads, etc., may be used.
The image forming unit 220 includes a developer 221 having a photosensitive drum 222 for forming a toner image on a print medium 13, a scanning unit 226 forming a latent image on the photosensitive drum 222 of the developer 221, a transfer roller 227 rotating correspondingly to the photosensitive drum 222 with the print medium 13 placed in-between, and a fuser 228 for fusing the toner on the print medium 13 where the toner image is formed.
The print medium 11 loaded on a knock-up plate 211 of the print media feeder 210 is picked up by a pick-up roller 212 and supplied into a register roller 214 through a conveyor roller 213.
The register roller 214 conveys the print medium 12 to between the photosensitive drum 222 and the transfer roller 227, according to a print medium-advancing signal of a controller (not shown).
When the print medium 12 is conveyed, the scanning unit 226 generates a laser light corresponding to an image data, which is then radiated on the photosensitive drum 222. Thus, an electrostatic latent image is formed on the surface of the photosensitive drum 222.
In the developer 221, toner stored in a toner storage 223 is transferred to the electrostatic latent image via a supply roller 224 and a developing roller 225 to thereby form a toner image. The toner image formed on the surface of the photosensitive drum 222 is transferred onto the surface of the print medium 13 by means of electric force of a transfer roller 227. The print medium 13, on which a toner image is transferred, passes through the fuser 228 and at the same time the toner is fused on the surface of the print medium. Thereafter, the print media is stacked, through the print media ejector 240, on a print media stacker 250 provided on top of the image forming apparatus.
The fuser 228 comprises a heating roller 229 placed at the upper side thereof and a press roller 230 placed at the lower side thereof.
The heating roller 229 houses a heater (not shown), which generates heat through an electric power supplied from the main body of the image forming apparatus 200. The print medium 13 being conveyed from the developer 221 is heated up by the heater and thus the toner transferred on the surface of the print medium 13 is melted.
The press roller 230 presses the print medium 13 being heated by the heating roller 229 towards the heating roller 229. Thus, the toner on the print medium 13, heated by the heating roller 229, is fused on the surface of the print medium 13 by means of the press roller 230.
As shown in
In addition, a push roller 231 and a print media-releasing member 232 are provided in the print media-ejecting side of the heating roller 229. The push roller 231 contacts and presses against the heating roller 229, and has a rotation shaft, which passes through the print media-releasing member 232. Thus, as shown in
The print media-releasing member 232 is wedge-shaped and has a claw member 232a, which is protruded inwards of the space A formed by the push roller 231.
Here, the rotation shaft may be protruded from both sides of the print media-releasing member 232 and the push roller 231 may be provided with a shaft hole, so that the rotation shaft may be inserted into the shaft hole.
As shown in
On the other hand, body portions 232b of the respective print media-releasing members 232 may be inter-connected to form an integral body. In addition, the push roller 231 may have a smaller or larger diameter so as to form the space A having a desired size.
By the use of the above-structured push roller 231 and the print media-releasing member 232, the print medium 13 passing through the fuser 228 can be prevented from sticking to the heating roller 229.
As shown in
In the above-described embodiment, the surface layer 229b of the heating roller 229 is formed of an elastic material, though part of or the entire heating roller 229, in addition to the surface layer 229b, may be formed of an elastic material.
In addition, the space A, which is formed by elastic deformation of the surface layer 229b in the heating roller 229, may have various shapes, depending upon the size of the push roller 231, the thickness of the surface layer 229b, the material forming the surface layer 229b, and the like. Therefore, these conditions must be considered when designing the claw member 232a of the print media-releasing member 232. In particular, the claw member 232a, in most instances, should not to protrude outside of the space A, so that the surface layer 229b can be prevented from being damaged due to the claw member 232a.
On the other hand, the push roller 231 and the print media-releasing member 232 of this embodiment may be applied to any roller used in the image forming apparatus 200 as long as its surface layer is formed of a resilient material. For example, the push roller 231 and the print media-releasing member 232 can be applied to the conveyor roller 235 (in
In addition, the fuser 228 including the above push roller 231 and the print media-releasing member 232 may be designed so as to be detachably mounted on the image forming apparatus 200.
As described above, aspects of the present invention provide an image forming apparatus and a fuser therefor, in which a print roller having a resilient surface layer is pressed by a push roller to form a space in-between, and a print medium attached to the print roller can be easily released therefrom by using the space, without damaging the print roller.
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.
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