Abstract:
An expansion box is used for an image forming apparatus including a main body part in which an image forming part is housed, and a sheet feeder cassette which is mounted to the main body part and in which sheets to be fed to the image forming part are contained. The expansion box is attached to the main body part, covers the sheet feeder cassette protruding from the main body part, and includes an opening through which a front part of the sheet feeder cassette is exposed. The image forming apparatus includes the main body part, the sheet feeder cassette and the expansion box. An assembly method of the image forming apparatus is also provided. The assembly method includes assemblage with attachment of the expansion box to the main body part and optionally a step of assemblage without attachment of the expansion box to the main body part.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an expansion box to be attached to a main body part of an image forming apparatus, the image forming apparatus to which the expansion box is attached, and a method of assembling the image forming apparatus.  
         [0003]     2. Description of the Related Art  
         [0004]     There is known an image forming apparatus in which a sheet contained in a sheet feeder cassette is fed by a sheet feeding mechanism, and an image is formed on the fed sheet by image forming techniques, for example, an electrophotographic process.  
         [0005]     Presently, various sizes of sheets are used (for example, A3, A4, A5, B4, B5, etc.). A certain image forming apparatus has such a structure that a sheet feeder cassette containing sheets is detachably attached to the image forming apparatus, the sheet feeder cassette is prepared for each of the sheet sizes, and the sheet feeder cassette is mounted to the image forming apparatus as the need arises. The size of the sheet feeder cassette typically corresponds to the size of the sheet to be contained.  
         [0006]     In the image forming apparatus with the structure stated above, an image forming apparatus has been proposed in which when a sheet feeder cassette with a frequently used sheet size (for example, A4 size) is mounted, the front surface of the sheet feeder cassette and the front surface of a cover of the image forming apparatus form a substantially same surface, so that an improved appearance is achieved. See, for example, JP-A-2001-114426, and JP-A-10-87099.  
         [0007]     However, as a result of continued image forming apparatus miniaturization, sheet feeder cassettes tend to protrude from the image forming apparatus, even when a sheet feeder for a common sheet size is used.  
         [0008]     As stated above, when the sheet feeder cassette protrudes, the overall appearance of the image forming apparatus may be adversely affected. On the other hand, when a main body frame of an image forming apparatus is made large to accommodate a sheet feeder cassette in a manner such that it does not protrude, e.g., when the front surface of the main body cover is made to lie in substantially the same surface as the front surface of the sheet feeder cassette, the image forming apparatus becomes large, and the benefits of having miniaturized the image forming apparatus are lost.  
         [0009]     While it is conceivable that two kinds of main body frames could be manufactured, e.g., large and small, to satisfy both customers who attach importance to a clean overall appearance, and customers who attach importance to minimizing the size of the overall image forming apparatus. However, in this approach, manufacturing costs are increased.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention has been made in view of the above circumstances and provides an expansion box and an image forming apparatus which can satisfy, without increasing manufacturing cost, customers who attach importance to clean overall appearance and customers who attach importance to minimizing the size of the overall image forming apparatus.  
         [0011]     According to an aspect of the present invention, an expansion box is used for an image forming apparatus that includes a main body part, in which an image forming part is housed, and a sheet feeder cassette mounted to the main body part that contains sheets to be fed to the image forming part. The expansion box, which is preferably attached to the main body part, covers the sheet feeder cassette protruding from the main body part and includes an opening through which a front part of the sheet feeder cassette is exposed.  
         [0012]     Accordingly, when the expansion box is attached to the main body part of the image forming apparatus, since the front part of the sheet feeder cassette is exposed through the expansion box, the front surface of the expansion box and the front surface of the sheet feeder cassette may lie in substantially the same surface. Accordingly, an image forming apparatus is obtained in which the sheet feeder cassette does not protrude in an unsightly manner. The sheet feeder cassette can be attached and detached through the opening in the expansion box.  
         [0013]     Thus, when the sheet feeder cassette protrudes from the small main body part, an improvement in appearance can be achieved by attaching the expansion box, if desired by the user. Moreover, when the expansion box is not attached, the size of the overall image forming apparatus is minimized. Thus, it is also possible to satisfy users who place primary importance on the size of the overall image forming apparatus, rather than on appearance.  
         [0014]     Accordingly, without increasing manufacturing cost, it is possible to satisfy both customers who attach importance to a having a clean and trim appearance and customers who attach importance to minimizing the size of the overall image forming apparatus.  
         [0015]     According to another aspect of the present invention, an expansion box is used for an image forming apparatus that preferably includes a main body part having a main body frame in which an image forming part is housed, a main body cover which covers the main body frame, and a sheet feeder cassette which is mounted to the main body part and in which sheets to be fed to the image forming part are contained. The expansion box preferably includes an expansion frame attached to the main body frame, and a front cover that covers the sheet feeder cassette protruding from the main body part. An opening through which a front part of the sheet feeder cassette is exposed is preferably provided in the front cover of the expansion box.  
         [0016]     The front cover of the expansion box preferably covers the sheet feeder cassette protruding from the main body part. Moreover, since the front part of the sheet feeder cassette is exposed through the front cover, the front surface of the front cover and the front surface of the sheet feeder cassette lie in substantially the same surface. Accordingly, an image forming apparatus is obtained in which the sheet feeder cassette does not protrude, and the sheet feeder cassette can be attached and detached through the opening, as described herein.  
         [0017]     Further, to increase the strength and rigidity of the expansion box, the expansion box may preferably include an expansion frame attached to the main body frame, and it may be constructed such that the front cover is attached to the expansion frame. Thus, for example, even if a person were to collide with the expansion box, it would not be easily damaged.  
         [0018]     According to another aspect of the present invention, an image forming apparatus includes a main body part in which an image forming part is housed, a sheet feeder cassette which is attached to the main body part containing sheets to be fed to the image forming part, and an expansion box which is attached to the main body part. The expansion box preferably substantially covers the sheet feeder cassette protruding from the main body part, and includes an opening through which a front part of the sheet feeder cassette is exposed.  
         [0019]     Since the expansion box is attached to the image forming apparatus, the image forming apparatus satisfies both customers who attach primary importance to having a clean and trim appearance and customers who attach primary importance to minimizing the overall size of the image forming apparatus.  
         [0020]     According to another aspect of the present invention, an assembly method for an image forming apparatus is provided in which plural types of image forming apparatuses are manufactured. The method includes assembling a main body part in which an image forming part is housed, a sheet feeder cassette which is mounted to the main body part and in which sheets to be fed to the image forming part may be contained, and an expansion box which covers the sheet feeder cassette protruding from the main body part and includes an opening through which a front part of the sheet feeder cassette is exposed. If an expansion box is desired, the assembly method includes attaching the expansion box to the main body part. Alternatively, if no expansion box is desired, then the step of attaching the expansion box to the main body part is omitted.  
         [0021]     As described above, according to the present invention, it is possible to satisfy, without substantially increasing manufacturing cost, both customers who attach primary importance to having a clean and trim appearance and customers who attach primary importance to minimizing the size of the overall image forming apparatus. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]     The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention.  
         [0023]      FIGS. 1A and 1B  depict laser printers according to an embodiment of the invention, wherein  FIG. 1A  is a view in which an expansion box is attached, and  FIG. 1B  is a view in which the expansion box is not attached;  
         [0024]      FIGS. 2A and 2B  depict a laser printer according to an embodiment of the invention, wherein  FIG. 2A  is a view illustrating attachment of an expansion frame and a rail member, and  FIG. 2B  is a view illustrating a state where the expansion frame and the rail member are attached;  
         [0025]      FIG. 3  depicts a laser printer according to an embodiment of the invention and illustrates attachment of a power switch;  
         [0026]      FIG. 4  depicts a laser printer according to an embodiment of the invention and illustrates attachment of a front cover;  
         [0027]      FIG. 5  depicts a laser printer according to an embodiment of the invention and illustrates mounting a process cartridge and a sheet feeder cassette; and  
         [0028]      FIG. 6  is a view schematically showing the inside of the laser printer according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.  
         [0030]      FIG. 1A  depicts a laser printer  10  in which an expansion box  100  of the invention is attached to a printer main body  12 .  FIG. 1B  illustrates a laser printer  11  in which expansion box  100  of the invention is not attached to the printer main body  12 .  
         [0031]     The printer main body  12  forms an image (e.g., a toner image) on the basis of image information input from an external device by well-known electrophotographic processes, and records the image on a sheet or the like. The electrophotographic process includes a series of steps in which a toner image is formed on a photosensitive body through the charging of the electrophotographic photosensitive body. An electrostatic latent image is formed by exposure, developed by toner, and transferred to a sheet, where it is heated and fixed so that the image is recorded on the sheet.  
         [0032]      FIG. 6  is a view schematically illustrating the inside of the laser printers  10  and  11 . Sheet feeder cassettes  60  are mounted to the printer main body  12  in upper and lower stages. In  FIG. 6 , the oblique lines indicate the optional presence of expansion box  100 . As illustrated, the printer main body  12  includes an image forming part  300  for forming an image on a sheet P. The image forming part  300  includes a process cartridge  20 , a transfer roller  28 , an optical scanner  30 , a fixing device  40 , conveyance rollers  34 , and a sheet exhaust roller  46 .  
         [0033]     The image forming process performed by the image forming part  300  will now be described. The process cartridge  20  includes therein a photosensitive body  22 , and a part thereof is exposed from the process cartridge  20 . Charging roller  24 , developing unit  25  including a developing roller  26 , and waste toner case  19  including a cleaning blade  18  are disposed around the photosensitive body  22 . Toner case  21  is connected to the developing unit  25 , and toner is supplied from the toner case  21  to the developing unit  25 .  
         [0034]     Transfer roller  28  is in contact with the photosensitive body  22  exposed from the process cartridge  20 . Laser light L emitted from the optical scanner  30  passes through a gap bored in the process cartridge  20 , scanning and thereby forming an image on the photosensitive body  22 .  
         [0035]     The photosensitive body  22  is rotated by a driving mechanism (not-shown), and the surface of the photosensitive body  22  is uniformly charged by the charging roller  24 . Next, by the optical scanner  30 , the laser light L forms the image on the surface of the photosensitive body  22 , scanning it in accordance with the input data so that an electrostatic latent image, corresponding to the desired printed image, is formed on the surface of the photosensitive body  22 . The electrostatic latent image is then developed by the toner on the developing roller  26 , and a toner image is formed on the surface of the photosensitive body  22 . Next, the toner image is moved to the transfer roller  28 .  
         [0036]     Sheets P, contained in the sheet feeder cassette  60  at either one of the upper stage or lower stage, are taken out one by one by a pickup roller  32 , and sent to the conveyance rollers  34 . The conveyance rollers  34  then convey each sheet P to the transfer roller  28 .  
         [0037]     With respect to each sheet P conveyed to the transfer roller  28 , the toner image on the surface of the photosensitive body  22  is transferred to the sheet P by the transfer roller  28 . The sheet P on which the toner image is transferred is then conveyed to the fixing device  40 , and held and conveyed by a heat roller  42  and a pressure roller  44 , so that the toner image is fixed to the sheet P by heat and pressure. After the fixation process is complete, the sheet P is removed by the sheet exhaust roller  46  and is stacked on a sheet exhaust tray  50 . Any toner not transferred to the sheet P by the transfer roller  28  and remaining on the surface of the photosensitive body  22  is scraped away by the cleaning blade  18  and stored in the waste toner case  19 .  
         [0038]     Also as shown in  FIG. 5 , the process cartridge  20  is detachably attached to the printer main body  12  by opening the sheet exhaust tray  50 . When the toner in the toner case  20  is exhausted, it can be exchanged with a new process cartridge  20 .  
         [0039]     The sheet feeder cassette  60  is also detachably attached to the printer main body  12 . Accordingly, when the sheets P run out, the sheet feeder cassette  60  is taken out and sheets P can be re-supplied to the sheet feeder cassette  60 . Thus, the sheet P supply operation is easy to perform.  
         [0040]     A sheet feeder cassette with a size corresponding to each sheet size is preferably prepared for every sheet size (for example, A3, A4, A5, B4, B5, etc.), and the sheet feeder cassette of each sheet can be mounted in the printer main body  12  as the need arises. The sheet feeder cassette  60  preferably contains sheets P having a normally used sheet size (for example, A4 size), and has a size proportional to the size of the sheet P.  
         [0041]     In the laser printer  10 , expansion box  100  is attached to the printer main body  12 , as shown in  FIG. 1A  and  FIG. 6 . Although the sheet feeder cassette  60  protrudes from the printer main body  12 , a front surface  110 A of the expansion box  100  and a front surface  60 A of the sheet feeder cassette  60  may lie in substantially the same surface. Thus, the front surface of the laser printer  10  becomes substantially flat, providing a pleasing clean and trim overall appearance.  
         [0042]     On the other hand, in the laser printer  11 , expansion box  100  is not attached to the printer main body  12 , as shown in  FIG. 1B  and  FIG. 6 . In this embodiment, since the expansion box  100  is not attached, the sheet feeder cassette  60  protrudes from the printer main body  12 , and the front surface of the laser printer  11  is not flat. However, since the expansion box  100  is not attached, the overall size of the laser printer  11  is minimized.  
         [0043]     Next, the details of the expansion box  100  and the laser printer  10  to which the expansion box  100  is preferably attached will be described. As shown in  FIG. 2A , a main body frame  14 , preferably made of a metal sheet or the like, is attached to a base  16 . The image forming part  300  and associated components are attached to the main body frame  14 . Expansion frames  102 , preferably box-shaped and made of metal sheets or the like, are attached to both sides of the front surface of the main body frame  14 . Rail members  104  along which the sheet feeder cassette  60  (see  FIG. 5 ) slides are preferably attached to the inside surfaces.  
         [0044]      FIG. 2B  illustrates an embodiment in which the expansion frames  102  and the rail members  104  are attached. The rail members  104  are preferably firmly fixed to both the main body frame  14  and to the expansion frames  102  by screws or other fasteners. When the sheet feeder cassette  60  (depicted in  FIG. 5 ) slides on the rails (e.g., to attach or detach the sheet feeder cassette  60 ) the rail members  104  do not rattle and the sheet feeder cassette  60  can be attached and detached in a stable manner.  
         [0045]     In an embodiment, each of the left and right rail members  104  is fixed to both the main body frame  14  and the expansion frame  102 . Separate short rail members (not shown) may optionally be individually attached to the main body frame  14  and to the expansion frame  102 .  
         [0046]     As shown in  FIG. 3 , in a preferred embodiment, a power switch  124  is attached to a switch fixing port  120  located in the front of the expansion frame  102 . Connector  126  may be attached to a tip of a wiring cord  128  and connected to power switch  124 . The wiring cord  128  is preferably made to pass through a harness  130  and is connected to a power supply (not shown) in the inside of the printer main body  12 .  
         [0047]     As illustrated in  FIG. 4 , a front cover  110  is preferably attached to the front surfaces of the expansion frames  102 . In an embodiment, pawls  106  and  107  are formed at the rear surface of the front cover  110 . The pawls  106  and  107  may be inserted in pawl fixing ports  105  and  109  of the expansion frames  102 , where the tip parts  106 A and  107 A of the pawls  106  and  107  are retained, so that the front cover  110  is easily mounted to the expansion frames  102 .  
         [0048]     A cassette port  108 , through which only the front part of the foregoing sheet feeder cassette  60  is exposed, is preferably formed in the front surface  110 A of the front cover  110 . In an embodiment, the sheet feeder cassette  60  can be attached and detached through this cassette port  108 . Since, in a preferred embodiment, only the front part of the sheet feeder cassette  60  is exposed through the cassette port  108 , the front surface  110 A of the front cover  110  and the front surface  60 A of the sheet feeder cassette  60  lie in substantially the same surface. In this embodiment, the front surface of the laser printer  10  appears to become substantially flat (see  FIG. 1A ).  
         [0049]     Switch port  140  is preferably bored in the front cover  110  at a position corresponding to the foregoing power switch  124 , and the power switch  124  is exposed through this switch port  140 . Vent port  202  may be formed at the side part of the front cover  110 . Thus, a space  204  (see  FIG. 4 ) surrounded by the front cover  110  and the expansion frame  102  may function as a duct for performing air intake and/or air exhaustion from holes  210  or the like formed in the main body frame  14  and connecting to the inside of the printer main body  12 .  
         [0050]     Expansion frames  102  and the front cover  110  are preferably not made as separate bodies. Expansion frames  102  and the front cover  110  may be integrally molded to promote the efficiency of the attachment operation.  
         [0051]     As shown in  FIG. 5 , a side cover  112  and an upper cover  114  are attached, and when the process cartridge  20  and the sheet feeder cassette  60  are mounted, the laser printer  10  to which the expansion box  100  is attached is completed.  
         [0052]     Upper cover  114  is preferably constructed to cover not only the printer main body  12  but also the expansion box  100 . Vent holes  200  are preferably also formed in the side cover  112 , and the air intake and/or air exhaustion can be performed via vent hole  200 .  
         [0053]     Next, the operation of a laser printer  10  according to aspects of the present invention will be described. As shown in  FIG. 1A , in the laser printer  10 , the sheet feeder cassette  60  does not appear to protrude from the laser printer  10  due to the presence of the expansion box  100  (the expansion frames  102  and the front cover  110 ), making the front surface of the laser printer  10  appear to be substantially flat. Thus, the laser printer  10  has an attractive clean and trim appearance.  
         [0054]     As described above, the expansion box  100  preferably includes expansion frames  102  attached to the main body frame  14 , and the front cover  110  is preferably attached to the expansion frames  102  (see  FIGS. 2 and 4 ). Since the expansion frames  102  are preferably made of metal sheets or any material having sufficiently high strength, the strength of the expansion box  100  is also sufficiently high. Thus, for example, even if a person were to accidentally collide with the expansion box  100 , it would not be easily damaged.  
         [0055]     Moreover, since the expansion frames  102  have sufficient strength, as described above, the rail members  104  (see  FIGS. 2A and 2B ) can be attached. Thus, the sheet feeder cassette  60  preferably slides in to the expansion box  100 . Accordingly, operability at the time of attachment and/or detachment of the sheet feeder cassette  60  is not impaired.  
         [0056]     The power switch  124  is preferably exposed through the front surface  110 A of the front cover  110  and may be disposed at the front surface of the laser printer  10 . Accordingly, operability is not impaired. In this embodiment, in addition to the power switch  124 , other operational devices, for example, a control panel  250  may be attached.  
         [0057]     Further, as described above, since the expansion box  100  may also function as a duct (the space  204  surrounded by the front cover  110  and the expansion frames  102  (see  FIG. 4 )), the air intake and/or air exhaustion of the printer main body  12  can be performed more efficiently.  
         [0058]     Next, the laser printer  11  without the optional expansion box  100  attached will be described. As shown in  FIG. 1B , a front cover  160 , side covers  112 , an upper cover  164 , and rail members (not shown) are attached to the main body frame  14  shown in  FIG. 2A . Process cartridge  20  and sheet feeder cassette  60  are mounted as illustrated, forming the laser printer  11  without expansion box  100  attached.  
         [0059]     In laser printer  11 , the upper cover  164  covers only the upper part of the main body frame  14 , different from the upper cover  114  of the laser printer  10 . Moreover, as shown in  FIG. 3 , the power switch  124  is preferably attached to the switch fixing port  122  formed in the front of the main body frame  14 .  
         [0060]     Although not shown, in the case of the laser printer  11  (without expansion box  100 ), the base  16  shown in  FIG. 12A  has a length preferably not exceeding dotted line D so that it is received within the main body frame  14 . Similarly, the rail member is also short so that it may be received within the main body frame  14 .  
         [0061]     Next, the operation of the laser printer  11  will be described. As shown in  FIG. 1B , in the laser printer  11 , the sheet feeder cassette  60  protrudes from the printer main body  12 , and the front surface of the laser printer  11  is not flat. However, since the expansion box  100  is not attached, the overall laser printer  11  is small in size.  
         [0062]     As described previously, the primary difference between laser printer  10  and the laser printer  11  is whether or not expansion box  100  is attached to the printer main body  12  (see  FIGS. 1A and 1B ). Thus, two configurations of laser printers  10  and  11  can be produced at low cost, i.e., the laser printer  10  in which the expansion box  100  is attached, and the laser printer  11  in which the expansion box  100  is not attached.  
         [0063]     Accordingly, in accordance with embodiments of the invention, advances in miniaturization of the printer main body  12  may satisfy the needs of customers whose primary interest is in minimizing the size of the printer. On the other hand, customers for whom aesthetics are paramount can also be satisfied without impairing operability of the printer, sheet feeder, power switch, or the like, by attaching the expansion box  100 , thereby providing a clean, trim appearance by concealing the sheet feeder cassette  60 , which protrudes from the printer main body  12 .  
         [0064]     As previously discussed, although it is conceivable that different size frames could be used, e.g., a large main body frame to conceal the front surface  60 A of the sheet feed box  60 , to satisfy customers who attach primary importance to aesthetics, manufacturing two sizes of frames causes manufacturing costs to become too high.  
         [0065]     However, in accordance with the presently disclosed embodiments, it is possible to satisfy, without increasing the cost, both types of customers with a single apparatus. Of course, although a laser printer  10  has been used as an example of an image forming apparatus to illustrate embodiments of the invention, the invention is not limited to a laser printer. For example, embodiments of the invention may be applied to any other image forming apparatus, such as copy machines, facsimile machines, compound copy and facsimile machines, and any other similar machine having a cartridge extending therefrom.  
         [0066]     Other preferred embodiments of the present invention are described below. In the expansion box of the present invention, the rail member along which the sheet feeder cassette slides may be attached to the expansion frame. In the above expansion box, the rail member along which the sheet feeder cassette slides may be attached to the expansion frame. Thus, since the sheet feeder cassette slides into the expansion box, it can be easily attached and/or detached. Accordingly, the operability of the sheet feeder cassette is not impaired.  
         [0067]     In the expansion box of the present invention, operational devices such as a power switch may be attached to the expansion frame. Moreover, a port through which the operational device is exposed may be formed in the front cover. Accordingly, even if the expansion box is attached, operability of the device is not impaired. Space savings of the main body part can also be attained by attaching operational devices, such as a power switch, to the expansion frame.  
         [0068]     In the expansion box according to embodiments of the present invention, one or more vent holes may be formed in the front cover, and the space surrounded by the front cover and the expansion frame may function as a duct.  
         [0069]     In embodiments of the above expansion box, a vent hole is formed in the front cover, and the space formed by the front cover and the expansion frame functions as the duct. Accordingly, when the expansion box is attached, air intake and/or exhaust to or from the inside of the main body can be efficiently performed. Since there are many cavity portions in the space surrounded by the front cover and the expansion frame, the flow of air is good, and the space is suitable as a duct.  
         [0070]     While the present invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but have the full scope defined by the language of the following claims, and equivalents thereof.  
         [0071]     The entire disclosure of Japanese Patent Application No. 2003-335189 filed on Sep. 26, 2003 including specification, claims, drawings and abstract is incorporated herein by reference in its entirety.