BRIEF DESCRIPTION OF THE DRAWINGS
These and/or other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic cross-sectional view illustrating a configuration of a conventional image forming apparatus.
FIG. 2 is a cross-sectional view illustrating a coupling configuration of a conventional laser scanning unit.
FIG. 3 is a schematic top-view illustrating a configuration of a conventional laser scanning unit.
FIG. 4A is a top perspective view schematically illustrating a coupling configuration of a laser scanning unit of an image forming apparatus according to an embodiment of the present general inventive concept.
FIG. 4B is a rear perspective view schematically illustrating a coupling configuration of a laser scanning unit of the first embodiment of the present general inventive concept.
FIG. 5A is a cross-sectional view illustrating a coupling configuration of a laser scanning unit of the first embodiment of the present general inventive concept.
FIG. 5B is a cross-sectional view illustrating a coupling configuration of a laser scanning unit of a second embodiment or other embodiments of the present general inventive concept.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures.
The same elements are given the same reference numerals in various embodiments, and they will be typically described in a first embodiment of the present general inventive concept, and may be omitted or unlabeled in other embodiments of the present general inventive concept.
An image forming apparatus 1 according to an embodiment of the present general inventive concept may have a structure similar to a conventional image forming apparatus including a paper feeding part 10 to hold and to feed printing paper therefrom, an image forming part 40 to form an image on a printing paper page fed from the paper feeding part 10, a fixing part 50 to fix a developer spread from the image forming part 40 on the printing paper page (e.g., by heat and/or pressure), a paper discharging part 60 to discharge the paper page on which an image has been formed, and a main body casing 70 to accommodate these components. The main body casing 70 includes a main body frame 170 (see FIG. 4A) supporting the respective components illustrated therein.
The image forming part 40 includes a developing cartridge 20 to spread the developer on the printing paper page to form an image thereon, and a laser scanning unit 30 to form an electrostatic latent image onto the photosensitive body 22 of the developing cartridge 20.
The laser scanning unit 30 includes a light source 31, a plurality of mirrors 33 which can change the path of the laser generated from light source 31 and enable it to be incident on a polygon mirror 35, which rotationally scans the laser beam onto the photosensitive body 22, and an operating part 36 to operate the polygon mirror 35. The laser scanning unit 30 also includes a casing 131 (see FIG. 5A) to accommodate these components, and coupling parts 133 which are provided on opposite sides of casing 131 to be coupled to main body frame 170.
As shown in the embodiment of FIG. 5A of the present general inventive concept, the coupling part 133 is provided to be extended from the casing 131 to form a free end in one side, or may be directly provided in the casing 131. The coupling part 133 may be respectively disposed on opposite sides of the casing 131, or may be provided as plural members on opposite sides. Here, the coupling part 133 may be provided in different shapes depending on the various methods that may be used to couple to the main body frame 170. That is, the coupling part 133 has a shape corresponding to a given respective coupling method such as glue coupling, screw coupling, pin coupling, or rivet coupling, etc.
Referring to FIG. 5A, a laser scanning unit 130 according to an embodiment of the present general inventive concept is coupled to the main body frame 170 by a screw. Accordingly, the coupling part 133 has an inserting hole 135 into which a screw 210 is inserted. A radius R4 Of the inserting hole 135 is desirably provided to be larger than a radius R3 of a male screw part 213 of the screw 210 so that contact between the male screw part 213 and a circumference of the inserting hole 135 is minimized sufficient to reduce thermal deformation and/or misalignment of the coupling part 133 with the main body frame coupling part 171.
Meanwhile, a radius R2 (e.g., defining the outer washer circumference) of a washer 220 disposed between the inserting hole 135 and a screw head part 211 is desirably provided one and a half times larger than a radius R1 of the screw head part 211 so as to reduce and/or minimize a screw coupling force. That is, the area in which the washer 220 is in contact with the coupling part 133 is enlarged to distribute the load (or weight) otherwise focused on the screw head part 211 into a wider distribution load (or weight), to disperse the screw coupling force. The radius R1 of the screw head part 211 may be the same radius as the radius R4. The present general inventive concept is not limited thereto. It is possible that the radius R1 of the screw head part 211 may be larger or smaller than the radius R4.
As shown in FIGS. 4A and 5A, the main body frame 170 according to an embodiment of the present general inventive concept includes a main body coupling part 171 coupled to a corresponding coupling part 133 of the laser scanning unit 130. Referring to FIG. 4A, the main body coupling part 171 includes a main body inserting hole 175 into which the male screw part 213 is inserted or received, correspondingly located in sufficient alignment with inserting hole 135 of the coupling part 133. The main body inserting hole 175 is provided to have the same diameter (or slightly larger) as the diameter of the male screw part 213. The inside of the main body inserting hole 175 provides a female screw part to receive the male screw part 213 therein.
Referring to FIG. 4A, the main body coupling part 171 includes (in a deformation limiting area) a deformation limiting cut-out 173 to limit deformation at “Z” in the main body supporting frame 170. Deformation otherwise generated by heat build-up inside the main body supporting frame 170 is transferred to the main body coupling part 171. The deformation limiting cut-out 173 (e.g., together with one or more of bolt 210, limiting hole 135, washer 220, and hole 175, etc.) reduces thermal deformation produced in the main body supporting frame 170 by fully or partially limiting the deformation to the main body coupling part 171. Additionally, the deformation limiting cut-out 173 also prevents (or reduces) the magnitude of thermal deformation generated in the main body coupling part 171 from being transferred to the main body frame 170. The deformation limiting cut-out 173 may have a shape of a groove or a hole.
Referring further to FIG. 4A, the main body coupling part 171 has a first free end part “X” facing in an opposing direction with respect to the facing direction of a second free end part “Y” of the main body frame 170 in which thermal deformation may be caused by heat generated in the fixing part 50. However, the deformation limiting cut-out 173 reduces, attenuates or sufficiently minimizes thermal deformation and/or misalignment of main body frame 170 in relation to the laser scanning unit 130. Accordingly, thermal deformation focused on the free end part “Y” of the otherwise conventional main body frame 170 is -now directed (fully or partially) towards the free end “X” (e.g., cross-sectional face parallel with line L2) of the main body coupling part 171 to reduce thermal deformation of the main body frame 170. The free end part “X” is defined by the deformation limiting cut-out 173, and the hole 175 is formed in the free end part “X”.
Thus, as depicted in FIGS. 4A and 5A, a direction of thermal deformation of the free end “X” generated at the deformation limiting cut-out 173 is desirably provided towards the same direction “A” as that of the free end “m” of the coupling part 133 of the laser scanning unit 130. This is so because in the case that the coupling part 133 of the laser scanning unit 130 and the main body frame 170 are thermally expanded (inside the main body), the thermal expansion of each is directed towards the direction of the free end part “m” of the coupling part 133 and which is also towards the direction of the free end “X” of the main body coupling part 171. Thus, thermal deformation of parts 133 and 171 is directed towards the same general direction. Accordingly, a shearing force is either not generated, is minimized and/or is reduced (in the inserting holes 135 and 175 to which screw 210 is coupled). Such reduction of shearing force adequately prevents undesirable deformation and/or misalignment.
As shown in FIG. 4A, the deformation limiting cut-out 173 in the shape of an open-ended “Π” may be provided to have a separate free end part “X”, or may be provided as a plurality of aligned parallel holes (or slots or an equivalent thereof) provided to have a predetermined overall length (e.g., when in parallel or other acceptable alignment with each other) sufficient to provide uni-directional thermal deformation. Also, the deformation limiting cut-out 173 may be provided to have any other shape or configuration suitable for reducing undesirable shearing force due to thermal deformation of the main body coupling part 171 coupled to with the laser scanning unit coupling part 133.
The width “L1” and the height “L2” of the deformation limiting cut-out 173 may be provided according to the type, kind and the size of the coupling units used to join or couple the coupling parts 133 to the main body frame 170 via main body coupling part 171. When using the screw coupling according to an embodiment of the present general inventive concept, the deformation limiting cut-out Z (e.g., 173 or its equivalent) is provided with dimensions (e.g., L1 together with L2) to accommodate the washer 220 so that any deformation generated in the coupling part 133 can be properly distributed around the vicinity of the deformation limiting cut-out 173. On the other hand, in the case that the width “L1” and the depth “L2” of the deformation limiting cut-out 173 are too large, too much undesirable deformation may be generated in the coupling part 133 by a deformation generated in an area in close proximity to the insertion holes 135 and/or 175.
According to an embodiment of the present general inventive concept, the coupling part 133 of the laser scanning unit 130 may be constructed of the same material as that of the main body coupling part 171. That is because a shearing force may be generated because of a difference in the thermal expansion coefficients of materials used for the coupling part 133, the main body coupling part 171, and the screw coupling part (i.e., when different materials are used). If different materials are used, then it is desirable to match or select as best as possible the thermal expansion coefficients for the particular electrophotographic printing apparatus being used or designed for the magnitude of internal thermal heat expected to be generated during normal repeated use of the apparatus.
As shown in FIG. 4B, in the bottom view of the main body coupling part 171, a reinforcement rib 177 is provided to reinforce the stiffness or strength of the main body coupling part 171. The reinforcement rib 177 is provided to reinforce the main body frame 170 otherwise reduced by the deformation limiting cut-out 173. The main body coupling part 171 may include additional holes 176 to define the reinforcement rib 177. Here, the reinforcement rib 177 is oriented in the lengthwise direction towards the free end “X” to limit or reduce the thermal deformation generated in the main body coupling part 171 and/or direct deformation towards the direction of the free end “X”.
The reinforcement rib 177 is provided to have a proper thickness in consideration of the thickness of the main body coupling part 171. Also, the reinforcement rib 177 may be provided as plural members disposed at predetermined intervals. See, for example, the embodiment of FIG. 4B of the present general inventive concept.
Referring to FIGS. 5A and 5B, the coupling part 133 is extended from the casing 131 in the above-described embodiments, but it may be directly provided in the casing 131. That is, a coupling hole may be provided in the surface of the casing 131 to which a screw is coupled, and the deformation limited cut-out 173 may be provided to circumscribe (e.g., FIGS. 4A and 4B) the coupling hole.
As shown in FIG. 4A, in the laser scanning unit 130 with the illustrated configuration (according to an embodiment of present general inventive concept), the free end “X” (of main body coupling part 171) is provided facing the same direction as the free end of “m” (of the coupling part 133 of the laser scanning unit 130) by incorporating or providing the deformation limiting cut-out 173. The heat generated inside the main body and thermal deformation thereof together with the thermal deformation generated by the laser scanning unit 130 are directed in the same direction as shown by the dotted arrows on each side of casing 131 of FIG. 5A. Accordingly, as a shearing force is avoided (or adequately reduced) around the screw coupling part 210. Thus, undesirable deformation such as bending or warping is avoided or is sufficiently reduced or minimized. Therefore, the laser scanning direction of the laser scanning unit 130 becomes more uniformly controlled to produce a consistently maintained and/or improved uniform image quality and/or reduced deterioration of same due to misalignment and/or undesirable shearing force created by thermal expansion and deformation in opposing directions at the screw coupling, for example.
As shown in FIG. 5B, the main body frame 170 includes a supporting frame 177 reinforcing the main body coupling part 176 in a part of the main body via a deformation limiting member 178. Such member 178 limits relative deformation between the main body 176 and the supporting frame 177.
The deformation limiting member 178 may be provided as a member having a thermal expansion coefficient “α3” smaller than a thermal expansion coefficient “α2” of the coupling part 133 and larger than a thermal expansion coefficient “α1” of the main body coupling part 176. Accordingly, in the case that a thermal deformation in the opposite direction with the coupling part 133 is generated by the thermal expansion of the main body 176, a larger thermal deformation (in an opposing direction) of deformation limiting member 178 than that of the main body coupling 176 is generated to counteract the thermal expansion of the main body coupling part 176. Accordingly, the thermal deformation direction of the main body coupling part 176 is more in directional alignment with that of coupling part 133.
According to the above-described second embodiment of the present general inventive concept, the deformation limiting cut-out 173 is provided to form the free end “X” facing in the same direction as the free end “m” of the coupling part 133, and the thermal deformation direction of the coupling part 133 is directionally aligned with that of the main body coupling part 171.
According to a third embodiment of the present general inventive concept, referring to FIG. 5B, in the case that it is difficult to provide a deformation limiting cut-out 173 in the main body coupling part 176, a supporting frame 177 may be provided in the lower part of the main body 176, and a deformation limited member 178 having a larger thermal expansion coefficient than that of the main body coupling part 176 may be provided between the supporting frame 177 and the main body coupling part 176, to thereby accord the thermal deformation direction of the main body coupling part 176 to be more in line with the direction of thermal deformation of the coupling part 133.
Accordingly, the deformation between the coupling part 133 and the main body coupling part 176 is reduced and the laser scanning direction of the laser scanning unit becomes more uniform, thereby maintaining a more uniform and/or improved image quality.
The above-described deformation limiting cut-out and the deformation limiting member are provided in the main body frame. However, they may be provided in the laser scanning unit casing or its coupling part.
Also, the above-described embodiment of the deformation limiting cut-out and the deformation limiting member may be used for not only the laser scanning unit and the main body frame but also may be used for the developing cartridge and the main body frame supporting the developing cartridge, and the heating roller and the pressing roller and the main body frame supporting these two components to reduce a thermal deformation generated by heat inside the main body.
According to the above-described non-limiting embodiments of the present general inventive concept, a deformation limiting cut-out limiting deformation is provided in the main body frame coupled to the laser scanning unit to minimize deformation of the laser scanning unit coupling part.
Also, according to other embodiments of the present general inventive concept, in the lower part of the main body frame may be provided a supporting frame and a deformation limiting member limiting deformation of the main body frame to minimize relative deformation with the laser scanning unit coupling part.
Accordingly, the deformation of the coupling part is reduced after prolonged use, and the laser scanning direction of the laser scanning unit is more uniformly maintained to provide uniform and/or improved image quality over an extended period of time.
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 and their equivalents.
Patent Application
20080013142
