KR100398872B1 - Lazer printer having duplication printing device - Google Patents

Abstract

In the laser printer capable of double-sided printing according to the present invention, after printing one sheet of paper loaded in a paper feed cassette and passing it through a developing unit and a fixing unit while transferring it to a first paper feed path, A laser printer capable of printing on both sides of the back of the paper by discharging the paper through the developing unit and the fixing unit while entering and transferring the paper to the first paper conveying path again via the paper reversing path and the second paper conveying path. And a control unit for automatically printing the black image periodically after a certain number of prints so that contaminants present in the backup roller of the fixing unit adhere to and remove the black image. According to this, contaminants of the backup roller can be removed very effectively without using a separate cleaning felt or a release roller coated with a conventional mold. Therefore, it is possible to solve the problems caused by using a backup roller coated with a conventional release agent to increase the lifespan and print quality of the backup roller. In addition, according to the present invention, not only do not use expensive cleaning felt, but also the release agent does not use a coating back-up roller, so that cost reduction can be achieved.

Description

Laser printer capable of two-sided printing {LAZER PRINTER HAVING DUPLICATION PRINTING DEVICE}

The present invention relates to a laser printer, and more specifically, to a laser printer capable of double-sided printing, a laser printer capable of double-sided printing capable of preventing contamination of the backup roller of the fixing unit by controlling the printing process without using a separate cleaning felt. It is about.

In general laser printers capable of double-sided printing, as shown in Fig. 1, the developing unit 20 and the fixing unit from the paper feeding cassette 10 in which a plurality of sheets P installed on the lower side of the main frame 1 are loaded. A first paper feed path 2 formed to pass through 30, a paper reversing path 2 'extending at a rear end of the first paper feed path 2, and the first paper feed path 2; And a second paper feed path (3) formed to branch at the rear end side of the first paper feed path (10) and join at the front end side of the first paper feed path (2).

A plurality of pairs of first feed rollers 4, 5, 6 are provided at a predetermined interval in the first paper feed path 2, and a plurality of pairs of inverted rollers are provided in the paper inverting path 2 '. 7) (8) is provided, and the 2nd feed roller 9 is provided in the 2nd paper feed path 3. As shown in FIG. The paper P loaded in the paper feed cassette 10 is picked up by the pickup device 11 and enters the first paper feed path 2, and the feed roller 4 installed in the first paper feed path 2. By 5) and (6), the developing unit 20 and the fixing unit 30 are sequentially passed.

The developing unit 20 includes a photosensitive drum 21 having an electrically chargeable layer, and having a photosensitive drum 21 in which a potential difference is generated at the place where it is charged by exposure of a light source, and in contact with the photosensitive drum 21. And a developing roller 22 for developing the latent electric image of the photosensitive drum 21 with toner.

The fixing unit 30 is provided with a pressure roller 31 and a backup roller 32 by pressing the image of the toner transferred to the paper while applying the heat and pressure to the paper while passing through the developing unit 20. do.

On the other hand, although not shown, a general laser printer converts an electrical signal of image data into an optical signal by scanning a charging unit for charging the photosensitive drum 21, and converts an electrical signal of image data into an optical signal to the electrical potential difference. And an exposure unit for forming a latent image.

Hereinafter, the printing process of the laser printer capable of general duplex printing configured as described above will be briefly described.

When a printing command is input, the photosensitive drum 21 is charged by the charging unit, and then an electrical latent image is formed on the photosensitive drum 21 by the exposure unit, and the electrical latent image of the photosensitive drum 21 is a developing unit. The image is developed by 20.

One sheet of paper picked up from the paper cassette 10 by the pickup device 11 enters the first paper feed path 2, and the first paper feed path by the feed rollers 4, 5, 6. As it is transported along (2), the developing unit 20 and the fixing unit 30 are sequentially passed, and the printing of the entire surface of the paper is performed in this process.

After the printing of the entire surface is completed, the paper is reversed from the paper inversion path 2 'at the end of the first paper transport path 2, and then enters and is transferred to the second paper transport path 3, and the first paper transport path 2 At the front end of the feed roller 4, the feeder 4 enters the first paper feed path 2 again and sequentially passes through the developing unit 20 and the fixing unit 30. In this process, the back side of the paper is printed. When the back of the paper is printed, the paper is sequentially passed through the developing unit 20 and the fixing unit 30 in the state that the image has already been printed on the front, so that the backup roller 32 of the fixing unit 30 The image formed on the front surface of the paper sticks to act as a pollution source of the backup roller 31. If the backup roller is contaminated for the above reasons, not only does it cause a deterioration of the image quality but also shortens its life, therefore, it is necessary to suppress and prevent contamination of the backup roller.

To this end, in the general laser printer, as shown in FIG. 1, the cleaning roller 33 containing oil is installed in the pressure roller 31 of the fixing unit 30, so that the pressure roller 31 and the backup roller 32 are installed. By supplying oil to the back roller 32, the releasability of the backup roller 32 is improved to prevent contamination of the backup roller 32.

However, the cleaning felt 33 as described above is very expensive and is widely used for high speed models, but the use of a large cost burden is difficult for low speed models. For this reason, in the low speed model, the backing roller 32 is coated with a material having good releasability to prevent contaminants from getting on the backing roller. However, the coating is easily worn and the life of the backing roller is increased due to deformation of the backing roller. There is a problem that the maintenance cost of the printer is increased due to the frequent replacement of parts.

The present invention has been made in view of the above, and repairs by effectively removing the contamination of the fixing unit backup roller through the control of the printing process without using a coated backup roller having problems such as expensive cleaning felt or wear. It is an object of the present invention to provide a laser printer capable of double-sided printing capable of reducing maintenance costs and improving image quality.

1 is a view schematically showing a laser printer capable of general duplex printing,

2 is a view showing a laser printer capable of printing on both sides according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

1; body frame 2; first paper feed path

2 '; Paper Inverter 3; Second Paper Feed Path

10; paper cassette 20; development unit

30; fixing unit 32; backup roller

An object of the present invention as described above, after picking one sheet of paper loaded in the paper feed cassette and transporting it to the first paper feed path, passing through the developing unit and the fixing unit, printing the entire surface of the paper, and then printing the paper. In the laser printer capable of printing on both sides of the back side of the paper by passing through the developing unit and the fixing unit while entering and transporting again to the first paper conveying path via the reverse path and the second paper conveying path It is achieved by providing a laser printer, characterized in that it comprises a control unit for automatically printing a black image periodically after the number of copies to contaminants present in the backup roller of the fixing unit to adhere to the black image to be removed.

According to a preferred embodiment of the present invention, the laser printer prints a black image on the front side of the paper and a general image on the back side of the paper during automatic printing of the black image, so that the double-sided printing is performed so that the black image of the paper is on the backup roller side of the fixing unit. Is set.

In addition, when the paper printed with the black image enters the fixing unit, the paper feed speed may be controlled slowly, thereby increasing the decontamination effect of the backup roller.

In addition, in order to obtain the same effect, it is also possible to control the sheet to stop and convey the paper for a time during which the black image printed sheet enters the fixing unit and is bitten by the fixing unit nip.

Such a laser printer according to the present invention can remove the contaminants of the backup roller very effectively without using a separate cleaning felt or a release roller coated backup roller. Therefore, it is possible to solve the problems caused by using a backup roller coated with a conventional release agent to increase the lifespan and print quality of the backup roller. In addition, according to the present invention, not only do not use expensive cleaning felt, but also the release agent does not use a coating back-up roller, so that cost reduction can be achieved.

Best Mode for Carrying Out the Invention Preferred embodiments of the present invention will now be described based on the accompanying drawings.

2 is a view schematically showing a laser printer capable of double-sided printing according to an embodiment of the present invention. For reference, in describing the embodiments of the present invention, the same reference numerals refer to the same parts as those in the related art.

As shown in Figure 2, the laser printer capable of double-sided printing according to an embodiment of the present invention has the same structure as the general laser printer shown in Figure 1 except that the cleaning felt is removed. Therefore, the detailed description of the configuration is replaced by the prior art and omitted here. In the laser printer of the present invention, a function performed by a backup roller coated with a conventional cleaning felt or a release agent, that is, a function of removing contaminants of the backup roller is performed by controlling a printing process.

The basic printing process of the laser printer capable of double-sided printing according to the present invention as shown in Figure 2 is not much different from the conventional case. That is, when a print command is input, the photosensitive drum 21 is charged by the charging unit, and then an electrical latent image is formed on the photosensitive drum 21 by the exposure unit, and the electrical latent image of the photosensitive drum 21 is The developing unit 20 develops a visible image. One sheet of paper picked up from the paper cassette 10 by the pickup device 11 enters the first paper feed path 2, and the first paper feed path by the feed rollers 4, 5, 6. As it is transported along (2), the developing unit 20 and the fixing unit 30 are sequentially passed, and the printing of the entire surface of the paper is performed in this process. The paper on which the front printing is completed is inverted from the paper reversing path 2 'at the end of the first paper transport path 2, and then enters and is transferred to the second paper transport path 3, and At the front end, the feed roller 4 enters the first paper feed path 2 again and sequentially passes through the developing unit 20 and the fixing unit 30. In this process, the basic printing process of printing on the back side of the paper is discharged.

Here, the laser printer according to the present invention, after the predetermined number of prints in the printing process as described above, by periodically printing the black image automatically to remove the contaminants present in the backup roller 32 of the fixing unit 30. To be removed.

When the black image is printed after the predetermined number of prints as described above, the contaminants on the backup roller 32 of the fixing unit 30 stick to the black image and are removed. It is not necessary to coat the release agent on the backup roller.

According to a preferred embodiment of the present invention, when printing a black image for removing contaminants of the backup roller to print a black image on the front side of the paper and to print a general image on the back side the black image on the backup roller side of the fixing unit It's good to be here.

In addition, if the paper on which the black image is printed enters the fixing unit and the paper feed speed is slowed down, the heat is applied to the paper, which increases the time that the viscosity of the printed black image surface is melted by heat. As the amount of contaminants on the backup roller sticks to the molten black image surface, the contaminants on the backup roller can be more effectively removed.

In addition, in order to achieve the same effect, the black image may be repeatedly transported and stopped several times during the time that the black image is stuck in the fixing unit nip.

After printing the black image for removing the contaminants of the backup roller as described above, a normal duplex printing process is performed, and after printing a certain number of sheets, the black image for the decontamination of the backup roller is automatically printed as described above. do.

As described above, the laser printer capable of double-sided printing according to the present invention automatically removes contaminants on the backup roller by automatically printing black images periodically after a certain number of prints, thereby removing contaminants on the backup roller. There is no need to use a separate cleaning felt or a release roller coated with a release agent as in the prior art.

That is, according to the present invention, it is possible to solve the problem of cost increase caused by using the cleaning felt and the problem of shortening the life of the backup roller caused by using the backup roller coated with the release agent.

According to the present invention as described above, it is possible to very effectively remove the contaminants of the backup roller without using a separate cleaning felt or a release roller coated with a release agent. Therefore, it is possible to solve the problems caused by using the backup roller coated with a conventional release agent to increase the lifespan and print quality of the backup roller, and also because the expensive cleaning felt and / or release agent does not use the coated backup roller. In addition, cost reduction can be achieved.

While the invention has been shown and described with respect to preferred embodiments for illustrating the principles of the invention, the invention is not limited to the construction and operation as shown and described. Rather, those skilled in the art will appreciate that many modifications and variations of the present invention are possible without departing from the spirit and scope of the appended claims. Accordingly, all such suitable changes, modifications, and equivalents should be considered to be within the scope of the present invention.

Claims (4)

After printing one sheet of paper loaded in the paper feed cassette and passing it through the developing unit and the fixing unit while transferring it to the first paper feed path, the paper is transferred to the paper reversing path and the second paper transport path. In the laser printer capable of double-sided printing to pass through the development unit and the fixing unit while passing through the development unit and the fixing unit again while passing through the first paper feed path via And a controller for automatically printing black images periodically after a predetermined number of prints so that contaminants present in the backup roller of the fixing unit adhere to and remove the black images. The method of claim 1, A double-sided printing is set such that a black image is printed on the front side of the paper and a general image on the back side of the paper during automatic printing of the black image so that the black image of the paper is placed on the backup roller side of the fixing unit. The method according to claim 1 or 2, A laser printer, characterized in that the paper feed speed is controlled slowly when a sheet printed with black images enters the fixing unit. The method according to claim 1 or 2, A laser printer characterized by controlling the paper to be stopped and conveyed for a time during which a black image-printed paper enters the fixing unit and is bitten by the fixing unit nip.