Patent Grant
7283769
This application claims the benefit of Korean Patent Application No. 2004-6972, filed on Feb. 3, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a driving apparatus of a developing apparatus of a laser printer, copier, or the like, and a developing apparatus using the driving apparatus, and more particularly, to a driving apparatus of a detachable developing apparatus capable of enhancing quality of a printed image by inducing uniform rotation and dampening of vibration even when a photosensitive unit and a developing unit are separately driven, and the detachable developing apparatus using the driving apparatus.
2. Description of the Related Art
In a laser printer, copier, combined printer, or the like, a developing apparatus for printing a processed image on a recording sheet is provided in the shape of a cartridge. In a related art, a photosensitive unit, the surface of which is scanned by a laser so that an electrostatic latent image can be formed on the surface thereof, and a developing unit for supplying toner to the photosensitive unit so that a toner image corresponding to the electrostatic latent image can be formed, are installed together in one cartridge. However, when the photosensitive unit and the developing unit are combined in one cartridge as above-mentioned, there is a problem in which even though the usable life of the photosensitive unit is generally much longer than that of the developing unit, the photosensitive unit must be replaced together with the developing unit when the developing unit reaches the end of its usable life, even if the photosensitive unit operates normally.
In order to solve this problem, as shown in
A structure and operation of such a detachable developing apparatus shown in
First, a driving force to the photosensitive unit 110 is transferred from a photosensitive drum driving gear 113 to a photosensitive drum gear 112 which forms an image on a recording medium, such as a paper 200. Accordingly, when the photosensitive drum gear 112 rotates, the photosensitive drum 111 joined to the photosensitive drum gear 112 also rotates. On the other hand, a driving force to the developing unit 120 is transferred to the developing roller 121 first, and while a first idle gear 125 rotates according to the rotation of the developing roller 121, a portion of the driving force is transferred to a supply gear 126, and a toner supply roller 122 rotates. In addition, the other portion of the driving force is transferred to an agitator gear 128 via the first idle gear 125 and a second idle gear 127. When the agitator gear 128 rotates, an agitator 123 joined to the agitator gear 128 also rotates, and, accordingly, toner is moved by the agitator 123 toward the toner supply roller 122. Power transfer of the photosensitive unit 110 and the developing unit 120 are done separately, and therefore all the loads applied to respective gears are reduced.
However, when the photosensitive unit 110 and the developing unit 120 are driven separately from each other, there is possibility that a contacting nip depth or width between the photosensitive drum 111 and the developing roller 121 may be uneven. In order to prevent this problem, when the developing unit 120 is pressed by the force of the spring after the developing unit 120 is completely installed at the main body, the axis of the rotating shaft of the developing roller 121 and the axis of the driving shaft of a driving gear 140 supported by the main body must be precisely aligned with each other. However, at least some eccentricity will occur due to tolerance or the like occurring during manufacturing and assembling processes. Therefore, when the driving gear 140 (see
Therefore, as shown in
As previously described, the driving force to the developing unit 120 is transferred to the developing roller 121 first via the driving gear 140 and the coupling member 130, and, thereafter, is transferred to the toner supply roller 122 and the agitator 123 via the idle gears 125 and 127. However, as shown in
Therefore, in the conventional art, in order to minimize frictional loads at the four sliding slots 138 formed at right angles with one another at the outer circumferential surface of the coupling disc 132, two pairs of rotation shafts 136 are installed at respective surfaces of the coupling gear 131 and the coupling drive 134 which face the coupling disc 132 to project from the respective surfaces, and to make an angle of 180° with each other on the respective surfaces. Also, sliding rollers 133 are fitted around the respective rotation shafts 136 so as to rotate in the sliding slots 138. Consequently, the structure of the coupling member becomes very complex due to the installation of such sliding rollers 133, and the cost thereof increases due to the installation of the rotation shafts 136 and the sliding rollers 133.
Accordingly, it is an aspect of the present invention to minimize friction occurring at sliding slots of a coupling disc by reducing a load applied to a coupling member or a driving gear which transfers driving power to a developing unit.
It is also an aspect of the present invention to maintain a nip depth between a photosensitive drum and a developing roller and enhance quality of a printed image by minimizing friction occurring at the sliding slots of the coupling disc and thereby causing the principal function of an Oldham's coupling, i.e., the function of correcting eccentricity occurring at a connected shaft to function smoothly.
It is also an aspect of the present invention to reduce cost by simplifying the structure of a coupling member.
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.
Accordingly, to achieve the above and/or other aspects, there is provided a driving apparatus of a detachable developing apparatus to transfer driving power of a driving element of the developing apparatus to a developing element including a shaft and a toner supply element including: a coupling member including a coupling drive which is connected to the driving element and to which the driving power is transferred from the driving element, a coupling gear to which the driving power is transferred from the coupling drive, and a coupling disc positioned between the coupling drive and the coupling gear to flexibly connect the coupling drive and the coupling gear to each other, and correct an eccentricity of the shaft between the driving element and the coupling gear; and a power transferring portion including a plurality of gears so as to transfer the driving power from the coupling member to the developing element.
In addition, to achieve the above and/other aspects, there is provided a developing unit of a detachable developing apparatus in which a photosensitive unit for transferring an electrostatic latent image formed by being exposed to a laser beam and the developing unit for forming a toner image by supplying toner to the photosensitive unit are separated from each other including: a driving element for transferring driving power to the developing unit; a developing element for forming a toner image by supplying toner to the photosensitive unit; a toner supply element for supplying toner to the developing element; a coupling member including a coupling drive which is connected to the driving element and to which driving power is transferred from the driving element, a coupling gear to which driving power is transferred from the coupling drive, and a coupling disc positioned between the coupling drive and the coupling gear for flexibly connecting the coupling drive and the coupling gear to each other, and capable of correcting eccentricity of the shaft between the driving element and the coupling gear; and a power transferring portion including a plurality of gears so as to transfer driving power from the coupling member to the developing element.
Furthermore, the foregoing and/or other aspects are achieved by providing a driving apparatus of a developing apparatus to transfer a driving power of a driving element of the developing apparatus to a developing element of the developing apparatus including a shaft, including: a coupling member which is connected to the driving element and to which the driving power is transferred from the driving element, and correcting an eccentricity of the shaft between the driving element and the coupling member; and a power transferring portion including a plurality of gears so as to transfer the driving power from the coupling member to the developing element, wherein at least one of the plurality of gears is a reduction gear to reduce a load applied to the coupling member from the developing element.
These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiment, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to the embodiment of the present invention, an example of which is illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiment is described below to explain the present invention by referring to the figures.
A conventional developing unit is designed so that after driving power of a motor pinion gear is transferred via a reduction gear, a driving gear, and a coupling member to a developing roller, a toner supply roller is rotated by an idle gear while the idle gear rotates according to the rotation of the developing roller. That is, external driving power is transferred to the developing roller first via the coupling member without speed reduction. Therefore, in the conventional developing unit, while a load applied to the coupling member increases, smooth operation of the coupling member is hindered.
To the contrary, referring to
Here, in the reduction gear 25 joined to the coupling member 30, as shown in
Since the reduction gear 25 exists between the coupling member 30 and the developing roller 21 and the toner supply roller 22, the load applied from the developing roller 21 and the toner supply roller 22 to the coupling member 30 is markedly reduced. That is, in the conventional case, the load applied to the coupling member is the same as a value obtained by summing up the frictional loads of the developing roller and the toner supply roller. However, in the present invention, a resulting value of summing up the frictional loads of the developing roller 22 and the toner supply roller 21, and then dividing the summed value by the speed reduction ratio of the reduction gear 25 is the load applied to the coupling member 30. At this time, the speed reduction ratio of a series of gears joined to each other from the coupling member 30 to the developing roller 21 or the toner supply roller 22 must be greater than 1. In particular, for the purpose of achieving smooth operation of the coupling member 30, the speed reduction ratio may be greater than 1.5:1.
load applied to the coupling member=Tdeve+Tsr×(27/21)×(26/27)=2.24 kgf·cm
On the other hand,
load applied to the coupling member =Tdeve×(27/26)+Tsr×(27/21)×(26/27)×(30/64) =1.05 kgf·cm
As described in the above examples, it can be found that, with the embodiment of the present invention, the load applied to the coupling member 30 is reduced to less than half of that of the conventional case. Therefore, as compared with the conventional coupling member 130, the coupling member 30 according to the embodiment of the present invention can be configured to have a simpler structure. That is, as previously described, in the conventional coupling member 130, in order to minimize the frictional load occurring in the sliding slots 138 due to the load applied to the coupling member 130, two pairs of the rotation shafts 136 are installed at the facing surfaces of the coupling gear 131 and the coupling drive 134 to project from the respective surfaces and to make an angle of 180° with each other on the respective surfaces, and sliding rollers 133 are fitted around the respective rotation shafts 136 so as to rotate in the sliding slots 138. However, since a respective smaller load is applied to the coupling member 30 according to the embodiment of the present invention, the coupling member 30 can be smoothly operated without the sliding rollers 133.
The structure of the coupling member 30 according to the embodiment of the present invention will be described with reference to
In order to perform the above functions, for example, four sliding slots 38 are formed at right angles with one another, i.e., equiangularly at the outer circumferential surface of the coupling disc 32. Here, the number of the sliding slots 38 is exemplary, and a greater number of sliding slots 38 may be formed according to a specific embodiment. In addition, two cylindrical sliding projections 35 are formed at the surface of the coupling drive 34 facing the coupling disc 32 to make an angle of 180° with each other, and the coupling drive 34 and the coupling disc 32 are joined to each other by inserting the sliding projections 35 into the sliding slots 38. In addition, two cylindrical sliding projections 35 are also formed at the surface of the coupling gear 31 facing the coupling disc 32 to make an angle of 180° with each other, and the coupling gear 31 and the coupling disc 32 are joined to each other by inserting the sliding projections 35 into the remaining sliding slots 38. At this time, the sliding projections 35 formed at the coupling drive 34 and the sliding projections 35 formed at the coupling gear 31 are alternately inserted into the sliding slots 38 of the coupling disc 32. With such a connection, the coupling member 30 can smoothly transfer the driving power to the reduction gear 25 whether or not an eccentricity exists between the connected shafts.
Since the load applied to the coupling member 30 is markedly reduced as compared with that of the conventional design, friction between the sliding projections 35 and the sliding slots 38 can be sufficiently reduced even without the conventional sliding rollers, and, accordingly, as compared with the conventional design, the coupling member 30 can secure smooth operation even with a simple structure, and vibration is correspondingly dampened.
With the present invention, since the Oldham's coupling member is connected to the developing roller and the like by an element of the reduction gear, the load applied to the coupling member can be minimized. Therefore, since friction occurring at the sliding slots of the coupling member can be reduced, the coupling member can be simply structured without using relatively complex members such as rollers. Thus, since the manufacturing process thereof can be reduced, and material costs and the like can be cut down, there is an advantage in which the manufacturing cost of the developing apparatus can be reduced.
Further, since the load applied to the coupling member is relatively small, the function of correcting eccentricity occurring at the shaft is achieved, and the nip depth between the photosensitive drum and the developing roller of the developing apparatus can always be maintained uniformly. Therefore, enhancement of image quality of the developing apparatus can be achieved.
Although an embodiment of the present invention has 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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2004-0006972 | Feb 2004 | KR | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5583630 | Kimura et al. | Dec 1996 | A |
| 5937241 | Kumar et al. | Aug 1999 | A |
| 5993101 | Kohno et al. | Nov 1999 | A |
| 6463234 | Arimitsu et al. | Oct 2002 | B2 |
| 20010022902 | Nittani et al. | Sep 2001 | A1 |
| 20020172531 | Harada et al. | Nov 2002 | A1 |
| 20030081966 | Wakamatsu et al. | May 2003 | A1 |
| 20040013446 | Morioka et al. | Jan 2004 | A1 |
| Number | Date | Country |
|---|---|---|
| 63-237068 | Oct 1988 | JP |
| 05-265271 | Oct 1993 | JP |
| 08-234643 | Sep 1996 | JP |
| 2003-021942 | Jan 2003 | JP |
| 95011877 | Oct 1995 | KR |
| 100320232 | Dec 2001 | KR |
| 1020030020021 | Mar 2003 | KR |
| 1020030043141 | Jun 2003 | KR |
| Number | Date | Country | |
|---|---|---|---|
| 20050169670 A1 | Aug 2005 | US |
