Housing assembly of OPC unit

A housing assembly of an OPC unit to protect an OPC drum in an image forming apparatus includes a main housing enclosing at least a half of a large-diameter OPC drum and provided with a main-opening selectively contacting a plurality of developing units and a plurality of sub-openings, a first housing and a second housing each mounted on a side of the main housing, a handle hingedly connected to the main housing, and a plurality of brackets mounted on opposite sides of the main housing. As a result, the housing assembly of the OPC unit allows easy development, electrification, exposure, image transfer and treatment of a waste toner, and reliability of the image developing process increases due to the fixation of the developing units. Also, since the exposure of the OPC drum is minimized, an area of the OPC drum to be contaminated can be reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 2003-72423, filed on Oct. 17, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present general inventive concept relates to a housing assembly of an organic photoconductive (OPC) unit, and in particular, to a housing assembly to protect an OPC drum on which an image to be printed is formed in an image forming apparatus.

2. Description of the Related Art

In general, an image forming apparatus, such as a copying machine, a printer, or a combined machine, is used for forming an image on an OPC medium and then printing the image on a recording medium. For example, a laser printer prints an image on a sheet of paper through a series of steps, e.g., forming a desired image on an OPC medium with a laser scanning unit (LSU) and then transferring a developed image onto a paper through an image transfer unit.

Such an image forming apparatus requires an OPC unit including an OPC medium for forming an image. For a mono-printer, a housing assembly of the OPC unit is typically formed in an integral structure to enclose not only an OPC drum but also a developing roller or the like.

A conventional housing assembly10of an OPC unit is described with reference toFIG. 1by way of an example. The housing assembly10includes a main opening14through which an OPC drum22projects, and a sub-opening12that serves as an exposure window.

As shown inFIG. 1, the housing assembly10entirely protects toner, a toner stirrer16for supplying the toner, a toner feeding roller18, a developing roller20, an electrification roller24, and an OPC drum22.

The toner feeding roller18serves to transfer the toner to the developing roller20and is located adjacent to the developing roller20, and the developing roller20is in contact with the OPC drum22with a developing nip or gap being formed between the developing roller20and the OPC drum22, so that the developing roller20develops an image formed by a laser scan unit26with the toner received from the toner feeding roller18to form a developed image on the OPC drum22.

As shown inFIG. 1, in general, the conventional housing assembly10is provided with a toner storage case13positioned higher than any of the developing roller20and the toner feeding roller18, so that the toner can be moved by weight toward the developing roller20through the toner feeding roller18.

However, such a housing assembly10for a mono image forming apparatus has a disadvantage in that it can not be employed in a color image forming apparatus provided with four respective color developers each for yellow, magenta, cyan and black.

In particular, in a color image forming apparatus of a multi-path type including one OPC medium and one image transfer medium, the OPC medium is developed while individually coming into contact with each developing unit in a state that a developing nip or gap is formed between the OPC medium and the developing unit. Therefore, it is not possible to employ such a construction of the conventional housing assembly that has been used in the conventional mono image forming apparatus provided with an developing roller, etc., in the color image forming apparatus, and it is required to develop a new housing assembly according to a novel concept.

Although a currently developed color image forming apparatus uses a hard type OPC drum, which is not a belt, it has to have a plurality of small-diameter OPC drums for colors and also a plurality of color developing units corresponding to the OPC drums. In the currently developed color image forming apparatus, an image is developed by the respective color developing units and transferred to a big-sized transfer belt from the respective OPC drums. Such a color image forming apparatus with the above construction is bulky and is manufactured at high costs.

In order to the solve the above problem, a method has been suggested, in which a plurality of movable developing units selectively contact one single small-diameter OPC drum one by one to develop a color image. However, this method has a problem of an unstable developing process because of the movable developing units, thereby losing reliability of a developing quality.

Alternatively, another method also has been suggested, which uses an OPC belt instead of the OPC drum. According to this method, a developing process is performed in a manner that respective color developing units are brought into contact with the OPC belt. However, it is difficult to maintain a constant tension of the OPC belt, and the OPC belt becomes loosened when being used for a predetermined time or a tension of the OPC belt attenuates, thereby causing a poor contact with the developing units.

SUMMARY OF THE INVENTION

Accordingly, in order to solve the above-mentioned and/or other problems, it is an aspect of the present general inventive concept to provide a housing assembly of an OPC unit to protect a large-diameter OPC drum of a color image forming apparatus and to allow a plurality of color developing units to selectively contact the OPC drum.

Another aspect of the present general inventive concept is to provide a housing assembly which has a large portion to cover an OPC drum so that the OPC drum is less subjected to contamination.

In order to achieve the above and/or other aspects of the present general inventive concept, there is provided a housing assembly of an OPC unit to protect an OPC drum, on which an image to be printed on a recording paper is formed in an image forming apparatus, the housing assembly including a main housing enclosing at least a half of the OPC drum, and at least one sub-housing mounted on a side of the main housing. Since at lease a half of the OPC drum can be protected, the OPC unit is blocked from environment and thus is less subjected to the contamination.

According to an aspect of the present general inventive concept, the main housing may be formed with a plurality of sub-openings and a main opening to receive one or more developing units. The plurality of sub-openings may include a first sub-opening through which the OPC drum comes into contact with an image transfer medium, a second sub-opening through which a waste toner is discharged, and a third sub-opening through which the OPC drum is exposed to light to modify a potential of an image forming surface of the OPC drum corresponding to an image. Also, the plurality of sub-openings may further include a fourth sub-opening through which an electrostatic elimination light guide and an electrification roller assembly are mounted on the main housing.

According to another aspect of the present general inventive concept, the sub-housing may include a first sub-housing mounted with an auger and a second sub-housing mounted with an electrostatic elimination light guide, and the main housing may include a handle hingedly connected to opposite sides of the main housing. Accordingly, the sub-openings facilitate exposure, electrification, image transfer, and removal of a waste toner, and the handle allows a user to easily mount and dismount the OPC unit.

In order to achieve the above and/or other aspects of the present general inventive concept, there is also provided a housing assembly of an OPC unit to protect an OPC drum on which an image to be printed on a recording paper is formed in an image forming apparatus, the housing assembly including a main housing enclosing at least a half of a large-diameter OPC drum having a diameter of 100 mm to 150 mm, a main opening through which a plurality of color developers selectively come into contact with the large-diameter OPC drum, and at least one sub-housing mounted on a side of the main housing.

According to an aspect of the present general inventive concept, the main housing may include a plurality of sub-openings through which the OPC drum is exposed, and through which a waste toner is removed, and the at least one sub-housing may include a first sub-housing provided with an auger and a second sub-housing provided with electrostatic elimination light guide.

According to another aspect of the present general inventive concept, the first sub-housing may be provided with an auger, the second sub-housing is provided with electrostatic elimination light guide, and the plurality of sub-openings may include a first sub-opening through which the OPC drum comes into contact with an image transfer medium, a second sub-opening through which the first sub-housing is mounted on the main housing, and through which the waste toner cleaned from the OPC drum is discharged, a third sub-opening through which the OPC drum is exposed to receive light to form an image, and a fourth sub-opening through which the second sub-housing is mounted on the main housing.

According to another aspect of the present general inventive concept, the first sub-housing may include a carriage space to temporarily carry the waste toner, an auger roller to unidirectionally transfer the waste toner, and a waste toner drop hole from which the waste toner escapes, and the second sub-housing may include a plurality of ribs. As a result, it is easy to treat the waste toner, and it is possible to efficiently prevent the removed waste toner from being scattered onto an OPC drum or an electrification roller.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2is an exploded perspective view illustrating an OPC unit100and a housing assembly according to an embodiment of the present general inventive concept,FIG. 3is a perspective view illustrating the OPC unit shown inFIG. 2, in which the housing assembly and an OPC drum are shown in an assembled state, andFIG. 4is a front elevational view illustrating the housing assembly viewed from an main opening side.

As can be seen fromFIG. 2, the inventive housing assembly may include a main housing102, a first sub-housing120, a second sub-housing130, a gear assembly500, brackets400and a handle300.

The main housing102can be formed with a main opening103and first to fourth sub-openings104,106,108and110. The main opening103can be an open space largely occupying the main housing102, substantially, as much as about ½ of the main housing102. A large-diameter OPC drum200having a diameter of 100 mm to 150 mm can be mounted in the main housing102within the main opening103. Four respective color developing units (not shown) can be selectively brought into contact with the OPC drum200through the main opening103. As can be seen fromFIG. 2, a supporter119can be formed below both sides of the main housing102to support the housing assembly. As can be seen fromFIG. 2, a drum axle210can be inserted into a pair of slits112through the main opening103, and then brackets400can be secured to the main housing102, thereby completing the assembling of the OPC unit100. Since at least half the large-diameter OPC drum200is covered as shown inFIG. 3, an area to be contaminated by an external environment can be reduced. Also, since the color developing units (not shown) come in contact with the large diameter OPC drum200in a fixed state, the reliability of a developing quality can increase.

Referring back toFIG. 2, the first sub-opening104can be formed on an upper end of the main housing102, where an image transfer unit (not shown) is mounted, and the first sub-opening104serves as a passage to transfer an image developed on the OPC drum200to the image transfer unit (not shown). That is, the OPC drum200and the image transfer unit (not shown) can cooperate (communicate) with each other through the first sub-opening104.

The second sub-opening106can be formed below a lower end of the first sub-opening104as can be seen fromFIGS. 2 and 4. A cleaning blade150and a scattering prevention member152, which prevents a waste toner from being scattered, can be provided on the main housing102at upper and lower sides of the second sub-opening106, respectively. A sealing member154, which also prevents the waste toner from being scattered, is provided on the main housing102at each end portion of the second sub-opening106. The first sub-housing120to be described later can be assembled to the main housing102through the second opening (seeFIG. 2) to transfer the waste toner, which is removed from the OPC drum200by the cleaning blade150, into a waste toner container (not shown).

The third sub-opening108can be formed on a bottom of the main housing102in a rectangular shape. A laser scanning unit (LSU) (not shown), which forms an image on the OPC drum using laser beam, is positioned to communicate with the OPC drum200through the third opening108to form an image on the OPC drum200through the third sub-opening108.

The fourth sub-opening110can be formed between the second sub-opening106and the third sub-opening108, and the second sub-housing130and an electrification roller assembly503, as shown inFIG. 2, are mounted on the main housing102through the fourth sub-opening110. That is, the electrification roller assembly503having an electrification roller505and an electrification roller cleaning roller504can be mounted to be in contact with the OPC drum through the fourth sub-opening110, and the second sub-housing130can be connected to the main housing102, thereby enclosing (covering) the fourth sub-opening110.

An auger roller122can be mounted inside of the first sub-housing120to transfer the waste toner toward a waste toner drop hole126, and an auger roller gear502is provided on a side of the auger roller122. A carriage space128can be formed inside of the first sub-housing120to temporarily carry the waste toner removed from the OPC drum200, and a plurality of snap projections to be inserted into the main housing102can be formed at a lower end of the first sub-housing120. The first sub-housing120can be connected to the main housing102via the screw holes124formed in the first sub-housing120, thereby enclosing (covering) the second sub-opening106.

The second sub-housing130can be provided with an electrostatic elimination light guide132on a side thereof, and a plurality of ribs508can be formed on an inner side of the second sub-housing130. In addition, a plurality of screw holes507can be formed on the second sub-housing for screw connection. The electrostatic elimination light guide132serves to guide electrostatic elimination light to the OPC drum200to eliminate static electricity from the OPC drum200. According to an aspect of this embodiment, the electrostatic elimination light guide132may be transparent or semitransparent. The plurality of ribs508prevent the toner removed by the electrification roller cleaning roller504from being scattered due to a rotation of the OPC drum200, the electrification roller505and the electrification roller cleaning roller504.

The gear assembly500may include first to fourth idle gears506,508,510and512, an electrification roller cleaning roller gear504, and an auger roller gear502, as shown inFIGS. 2 and 3. The first to third idle gears506,508and510can transmit a power received from a flange gear222disposed on a side flange220of the OPC drum200to the electrification roller cleaning roller gear504to clean the electrification roller505, and the fourth idle gear512can transmit the power from the electrification roller cleaning gear504to the auger roller gear502.

As shown inFIG. 2, the brackets400can be mounted on the opposite sides of the main housing102by coupling the brackets400to shafts114of the main housing102through bracket holes402using a plurality of screws, and each bracket450may include a shock absorbing bar404, a coil spring406, and a support member408. The shock absorbing bar404comes in contact with the image transfer unit (not shown) when the image transfer unit is seated on a top end of a housing assembly101ofFIG. 4, the coil spring406can elastically support a bottom of the shock absorbing bar404, and the support member408can receive the coil spring406and the shock absorbing bar404and can be secured to the main housing102. As a result, when the image transfer unit (not shown) is seated on the top end of the housing assembly101, the bracket400can absorb an impact.

The handle300can be provided with openings306to correspond to a shaft118of the main housing104, so that it can be hingedly connected to the opposite sides of the main housing102by coupling ends of the lateral leg part304to shafts118formed on the respective opposite sides of the main housing102through openings306, and may include an anti-slip part302and lateral leg parts304. Each of the lateral leg parts304can be formed with a hook part308to be latched to a flange seating part115of the main housing102. Additionally, a housing assembly of the OPC unit100having the OPC drum200and used with an image forming apparatus having one or more developing units and the image transfer unit may include the main housing102having opposite sides to correspond to the side flanges220of the OPC drum200, a plate601formed between the opposite sides to correspond to an image forming surface of the OPC drum200in a circumferential direction of a rotation axis of the OPC drum200and having an angle larger than 18020with respect to the rotation axis of the OPC drum200to define with the opposite sides the main opening103through which a portion less than 50% of the image forming surface of the OPC drum200is exposed a sub-opening (e.g.,108,110,106, and/or104) formed on the plate601in a direction along the rotation axis of the OPC drum200, and a sub-housing (e.g.120and/or130) attached to the main housing102to communicate with the image forming surface of the OPC drum200through the sub opening (e.g.,108,110,106, and/or104).

Hereinbelow, an operating relationship of the inventive housing assembly101constructed as described above in a state that the housing assembly101is assembled with the OPC drum will be described in detail.

When the OPC unit100shown inFIG. 3is mounted in a main body of an image forming apparatus (not shown), a power source (not shown) can be inserted into the main housing102through a power source insertion part116(seeFIG. 3) to be engaged with the flange gear222. Upon being engaged in this manner, the flange gear222can be rotated by the power source to rotate the OPC drum200, and also can render the first idle gear506engaged with the flange gear, the second idle gear508, and third idle gear510to be rotated in sequence. The third idle gear510can rotate the electrification roller cleaning roller504, so that the electrification roller cleaning roller504can perform cleaning of the electrification roller505while being rotated and being in contact with the electrification roller505. The electrification roller cleaning roller504can rotate the fourth idle roller512, and the fourth idle roller512can rotate the auger roller gear502, so that the auger roller122and auger123transfer the waste toner. Yellow, magenta, cyan and black developers (not shown) are individually positioned in the main opening103of the main housing102, and an image transfer medium (not shown) is disposed to face the OPC drum200through the first sub-opening104with a nip or gap being formed therebetween.

Firstly, if the OPC drum200is exposed through the third sub-opening108, an image to be printed can be formed on the OPC drum200. According to the image formed in this manner, respective color developing units (not shown) come into contact with the OPC drum200with a developing gap or nip to develop the image with respective colors. The developed toner image can be transferred to the image transfer medium (not shown) through the first sub-opening104. The waste toner, remaining on the OPC drum200after image transfer, can be removed by the cleaning blade150and then can drop into the carriage space128provided inside of the first sub-housing120through the second sub-opening106. Thereafter, the waste toner can be moved to the waste toner drop hole126by the auger roller122and the auger123and then freely drops into a waste toner sump (not shown). When the cleaning is completed, electrostatic elimination is performed using the electrostatic elimination light guide132and the fourth sub-housing110.

The housing assembly of an OPC unit as constructed above according to this embodiment of the present general inventive concept can reduce an area to be contaminated by external environment by covering at least half the large-diameter OPC drum in the color image forming apparatus.

In addition, due to the presence of the main opening103, contact between the fixed color developing units and the OPC drum can be improved, which consequently contributes improvement of an image developing quality.

Also, the inventive housing assembly is excellent in assemblability, and, by providing the handle300and the waste toner carriage space in the housing assembly, it is easy to mount and dismount the OPC unit and to remove the waste toner.

Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims. Therefore, it shall be considered that such modifications, changes and equivalents thereof are all included within the scope of the present invention.