This application claims priority from Korean Patent Application No. 10-2008-0048065, filed on May 23, 2008, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to formation of color images, and more particularly, to forming a latent image on an image forming medium, developing the latent image, transferring the developed image to a recording medium, and fixing the transferred image on the recording medium.
2. Description of the Related Art
Generally, an electrophotographic image forming apparatus forms images using the following method. An image forming medium whose entire surface is charged with a predetermined polarity is exposed to light according to image data to be recorded so as to form a latent image on the surface of the image forming medium. Then, the latent image is developed with a developer, such as toner, to form a developed image. The developed image is transferred to a recording medium and the transferred image is fixed on the recording medium, thereby completing the formation of an image on the recording medium.
As described above, to form images, conventional electrophotographic image forming apparatuses necessarily require an apparatus and process for charging the entire surface of an image forming medium with a predetermined polarity, and a process for exposing the surface of the image forming medium. Due to such necessary requirements, there is a limit to reducing time required for data printing.
Conventional electrophotographic color image forming systems can be categorized into multi-pass type color image forming systems and single-pass type color image forming systems.
In multi-pass type color image forming systems, cyan toner, magenta toner, yellow toner, and black toner are sequentially applied to an image forming medium to develop a latent image. That is, only one image forming medium is treated with four toners.
In single-pass type color image forming systems, each of cyan toner, magenta toner, yellow toner, and black toner is applied to respective image forming media to develop a latent image. That is, four drums which are aligned with each other are used to form color images.
However, in a multi-pass type color image forming system, a developing rate is low due to the sequential treatment with four colors. In addition, in a single-pass type color image forming system, four sets of image forming media and developing devices are required for the four colors and thus, additional components are required and the apparatus structure is complex, and the manufacturing costs are high.
Exemplary embodiments of the present invention provide an image forming apparatus for forming a color image using an image forming medium including a plurality of cells, in which the cells are disposed in a matrix and each cell operates independently without a photoreceptor, and different color toners are sequentially attached in a multi-layer structure to the cells while the amount of the charge applied to the cells is gradually increased.
Exemplary embodiments of the present invention also provide a method of forming a color image using the image forming apparatus.
According to an aspect of the present invention, there is provided image forming apparatus including: an image forming medium which has a surface comprising a plurality of cells, wherein each cell operates independently, and the cells are charged according to a color image to be recorded so as to form latent images; a developing unit which comprises a plurality of toner cartridges containing different color toners, wherein the toner cartridges are aligned around the image forming medium and spaced apart from each other at predetermined intervals, and which develops the latent image into the color image; a transferring unit which transfers the color image to a recording medium; and a fixing unit which fixes the color image that has been transferred to the recording medium, wherein the latent images are developed with different color toners, according to the order in which the cells face the toner cartridges.
According to another aspect of the present invention, there is provided method of forming a color image, the method including: forming a latent image by charging a plurality of cells to have an opposite polarity to an original polarity of the cells according to an order in which the cells face a plurality of toner cartridges containing different color toners; developing the latent image with a corresponding color toner to develop a color image;
transferring the developed color image to a recording medium; and fixing the transferred color image on the recording medium.
The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.
Referring to
The image forming medium 100 may be a cylindrical photoreceptor. The image forming medium 100 includes a rotary body 101, and a peripheral portion 102 disposed on a circumferential surface of the rotary body 101, wherein the peripheral portion 102 includes the cells 200 (
Referring to
A device that can change polarity of the cell 200 is disposed in the space portion 210 of the cell 200. The device may be a condenser 230 illustrated in
The first plate 231 and the second plate 232 are also connected to an initializing switching device 237. The initializing switching device 237 connects the first plate 231 to the second plate 232 and neutralizes each of the first and second plates 231 and 232.
Accordingly, when the first and second charge switching devices 233 and 235 are turned on, the initializing switching device 237 is turned off. On the other hand, when the initializing switching device 237 is turned on, the first and second charge switching devices 233 and 235 are turned off.
The first and second charge switching devices 233 and 235 and the initializing switching device 237 can be various types of devices that can cause electrostatic phenomena and can be controlled according to a signal applied thereto.
As described above, an image forming medium used according to the exemplary embodiment of the present invention has a different structure from that of conventional photoreceptors and can change its polarity by itself. In this aspect, the image forming medium used according to the exemplary embodiment of the present invention can be referred to as a self image forming medium.
The developing unit 110 includes a plurality of toner cartridges which are spaced apart at predetermined intervals and are sequentially aligned round the image forming medium 100. The toner cartridges include a cyan toner cartridge 110C containing cyan toner, a magenta toner cartridge 110M containing magenta toner, a yellow toner cartridge 110Y having yellow toner, and a black toner cartridge 110K storing black toner. Toners contained in the cyan, magenta, yellow and black toner cartridges 110C, 110M, 110Y, and 110K may have a negative charge (−).
In
The transferring unit 120 transfers a color image formed by the developing unit 110 to the recording medium 104. Specifically, when the transferring unit 120 passes the nip N formed between the transferring unit 120 and the image forming medium 100, a portion of the image forming medium 100 passing the nip N is charged with such polarity that the toner forming the color image is detached. Thus, a repulsion force is generated between the image forming medium 100 and the toner forming the color image, and the transferring unit 120 is charged with a polarity so as to attract the toner forming the color image so that an attraction force is generated between the transferring unit 120 and the toner forming the color image. For example, the portion of the image forming medium 100 passing the nip N may be charged with a negative charge (−) and the transferring unit 120 may be charged with a positive charge (+). The transferring unit 120 may be a transfer roller.
The fixing unit 130 fixes the color image that has been transferred to the recording medium 104 by the transferring unit 120. The fixing unit 130 includes a heating roller 131 generating heat, and a pressing roller 132 facing the heating roller 131 and applying pressure. Accordingly, the color image passing through between the heating roller 131 and the pressing roller 132 is heated and pressed and thus fixed on the recording medium 104.
The cleaning unit 103 removes the residual toner on the surface of the image forming medium 100 after the transferring unit 120 completely transfers the color image. In fact, however, the transferring unit 120 cannot completely transfer the color image and a predetermined amount of toner necessarily remains on the surface of the image forming medium 100. Since the residual toner degrades the image quality in the subsequent printing process, the residual toner should be removed to obtain high image quality after the transferring process is completely performed. To this end, an electrical state of the surface of the image forming medium 100 is initialized to remove the residual toner on the surface of the image forming medium 100. For example, a portion of the image forming medium 100 on which toner remains is neutralized so that negatively charged toner is easily removed from the image forming medium 100.
The control unit 300 changes polarities of the cells 200 using a line control mode as illustrated in
In the line control mode as illustrated in
In the cell control mode as illustrated in
Hereinafter, a method of forming a color image using the image forming apparatus according to the present invention will now be described in detail.
Referring to
After Operation 510, the latent image is developed with the corresponding color toner and the color image is formed on the image forming medium 100 (Operation 520 of
Operation 510 and Operation 520 will now be described in detail.
Referring to
Referring to
Referring to
Referring to
Referring to
As described above, when the image forming medium 100 passes by the cyan, magenta, yellow and black toner cartridges 110C, 110M, 110Y, and 110K, the cyan toner 111, a latent image is developed and a color image to be recorded is formed on the image forming medium 100.
In this regard, once color toner is attached to a cell and the cell is developed, static electricity that allows other color toner to be attached to the color toner that has been attached to the cell is not generated even when the cell passes by a toner cartridge containing the other color toner. Therefore, even when a cell to which one type of color toner is attached continually has a positive (+) charge, other color toner may not be attached to the toner.
After Operation 520, when the color image formed on the surface of the image forming medium 100 passes through the nip N between the transferring unit 120 and the image forming medium 100, the color image is transferred to the recording medium 104 due to a static electricity (Operation 530 of
After Operation 530, when the color image transferred to the recording medium 104 passes the fixing unit 130, the color image is fixed on the recording medium 104 (Operation 540 of
After Operation 540, when the image forming medium 100 passes by the cleaning unit 103, the cleaning unit 103 neutralizes an electrical state of the cell 200 (Operation 550 of
As described above, an image forming apparatus and a method of preparing the same according to the exemplary embodiments of the present invention have the following effects.
First, latent images of a plurality of cells, each operating independently, can be developed in different color in the order in which the cells face the toner cartridges. Therefore, a color image forming rate can be increased.
Second, polarity of the cells of an image forming medium can be self-changed and a latent image can be formed independently. Therefore, the structure of apparatus can be simplified and miniaturized.
Third, the miniaturization of the apparatus and the number of necessary components is reduced. Therefore, the manufacturing costs can be lowered.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Number | Date | Country | Kind |
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10-2008-0048065 | May 2008 | KR | national |