Abstract:
An image forming apparatus having a casing, a first cover and a second cover. The first cover is rotatable between a first opened position to expose a first opening and a first closed position. The second cover is rotatable between a second opened position to expose a second opening and a second closed position. The first cover is sized and positioned relative to a toner cartridge to rotate to the first opened position to permit removal of the toner cartridge that is detached from a developing unit while the second cover is maintained in the second closed position. The first cover and the second cover are sized and positioned relative to the developing unit and a photosensitive body to rotate respectively to the first opened position and the second opened position to permit removal of the developing unit and the photosensitive body integrally.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a continuation application of U.S. patent application Ser. No. 14/223,484 filed on Mar. 24, 2014 which is a continuation application of U.S. patent application Ser. No. 13/398,973 filed on Feb. 17, 2012 which is a continuation application of U.S. patent application Ser. No. 13/197,381 (now U.S. Pat. No. 8,135,306, granted Mar. 13, 2012) filed on Aug. 3, 2011, which is a continuation application of Ser. No. 12/508,938 (now U.S. Pat. No. 8,014,699, granted Sep. 6, 2011) filed on Jul. 24, 2009 and claims priority from Japanese Patent Application No. 2008-191615, filed on Jul. 25, 2008, the disclosures of each of which are incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image forming apparatus which includes a plurality of process units and a supporting frame which integrally supports the process units. 
     2. Description of the Related Art 
     An image forming apparatus, in which a plurality of process units each having a photosensitive body and a developer container are integrally supported by a supporting frame in a state of being arranged in parallel in one direction, and the supporting frame is detachable from a casing of the apparatus in one direction has hitherto been known (refer to Japanese Patent Application Laid-open No. 2006-292982). Moreover, in this technology, the supporting frame is mounted to be hidden under an exposure member which exposes the photosensitive body, and accordingly, all the process units supported by the supporting frame are facing the exposure member in a vertical direction. 
     However, in the abovementioned technology, since each of the process units is formed in a size to be hidden under the exposure member in order that each of the process units and the exposure member do not interfere with each other, it is not possible to secure a sufficient size of the developer container. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an image forming apparatus, in which it is possible to secure a sufficient size of the developer container without each of the process cartridges interfering with the exposure member. 
     According to a first aspect of the present invention, there is provided an image forming apparatus which forms an image, including a plurality of process units arranged in a predetermined direction to form a process-unit row, each of the process units having a photosensitive body and a developer container; a casing accommodating the process units, and having an opening which is formed in the casing at one side in the predetermined direction, and a cover which opens and closes the opening; and an exposure member exposing the photosensitive body, and having a laser source, a deflector which deflects laser beam emitted from the laser source, and an optical element which focuses the emitted laser beam, the exposure member being arranged to face the developer container of each of the process units in a direction orthogonal to the predetermined direction; and the process units are detachable, with respect to the casing, through the opening of the casing; and the developer container of one process unit, among the process units, arranged at one end of the process-unit row has a protruding portion which protrudes toward the exposure member to overlap with the exposure member in the direction orthogonal to the predetermined direction. 
     According to the first aspect of the present invention, since the developer container of the one process unit arranged at one end of the process-unit row has a protruding portion which protrudes toward the exposure member to overlap with the exposure member in the direction orthogonal to the predetermined direction, it is possible to secure a sufficient size of the developer container of the one process unit arranged at one end of the process-unit row. Moreover, even when the protruding portion of the developer container of the one process unit protrudes toward the exposure member, since the one process unit is detachable with respect to the casing through the opening of the casing (opposite side of the exposure member), it is possible to prevent interference of the one process unit and the exposure member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side cross-sectional view showing a color laser printer according to an embodiment of the present invention; 
         FIG. 2  is a side cross-sectional view showing a structure at a front side of a casing; 
         FIG. 3  is a side cross-sectional view showing a state in which a replacement job of a toner cartridge is performed; 
         FIG. 4  is a side cross-sectional view showing a state in which a replacement job of a developer unit at an extreme front side is performed; 
         FIG. 5  is a side cross-sectional view showing a state in which a replacement job of a process unit at the extreme front side is performed; and 
         FIG. 6  is a side cross-sectional view showing a state in which a replacement job of one of three process units at an inner side is performed. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present invention will be described below in detail while referring to the accompanying diagrams.  FIG. 1  is a side cross-sectional view showing a color laser printer according to the embodiment of the present invention. In the following description, firstly, an overall structure of the color laser printer as an example of an image forming apparatus according to the embodiment will be described referring to  FIG. 1 , and thereafter, a detail structure of a process unit will be described. 
     As shown in  FIG. 1 , a color laser printer  1  according to the embodiment includes mainly a paper feeding section  3  which supplies a paper P to inside a casing  2  of the color laser printer  1 , and an image forming section  4  which forms an image on the paper P supplied from the paper feeding section  3 . 
     In the following description, except where specifically noted, upward direction and downward direction shown in  FIG. 1  are referred to as an upper side and a lower side respectively, a left side in  FIG. 1  is referred to as a front side, a right side in  FIG. 1  is referred to as a rear side, an inner side of a paper surface is referred to as a left side, and a front side of the paper surface is referred to as a right side. Directions in the description are based on directions viewed from a person standing at a front side of the color laser printer  1 . 
     The paper feeding section  3  includes a paper feeding tray  31  which is detachably installed on the casing  2 , and a paper supplying mechanism  32  which transports the paper P from the paper feeding tray  31  to the image forming section  4 . Moreover, in the paper feeding section  3 , the papers P in the paper feeding tray  31  are transported one-by-one to the image forming section  4  arranged above by the paper supplying mechanism  32 . 
     The image forming section  4  includes a scanner section  5  as an example of an exposure member, four process units  6 , a transfer section  7 , and a fixing section  8 . 
     The scanner section  5  includes a laser source which is not shown in the diagram; a polygon mirror  51  as an example of a deflector which deflects laser beam irradiated from the laser source; and a plurality of lenses  52  and  53  and a reflecting mirror  54  as an example of optical elements which form an image of the laser beam irradiated. In the scanner section  5 , laser beam corresponding to each color namely cyan, magenta, yellow, and black is irradiated to each photosensitive drum  61 A of each process unit  6 . 
     Each process unit  6  is integrally supported by a supporting frame  9  in a state of being arranged in a frontward and rearward direction (a predetermined direction). Each process unit  6  is detachable from the supporting frame  9 . 
     Moreover, the supporting frame  9  is taken out and put in in the frontward and rearward direction to be detachable with respect to the casing  2 . In other words, each process unit  6  is detachable from the casing  2  via the supporting frame  9 . The supporting frame  9  has a shape of a frame surrounding each process unit  6 . Concretely, the supporting frame  9  has a pair of side frames  91  (only one side frame  91  is shown in the diagram) arranged at left and right of each process unit  6 , a rear frame  92  which connects rear ends of the pair of side frames  91 , and a front frame  93  which connects front ends of the pair of side frames  91 . 
     Here, the front frame  93  is provided at a lower portion of front ends of the side frames  91  such that it does not lie in the way at the time of removing a process unit  6 A at an extreme front side from the supporting frame  9  in the front side direction as it will be described later. Moreover, a handle  94  to be held by a user is provided at a front side of the pair of side frames  91 . 
     The process unit  6 A arranged at the extreme front side out of the four process units  6  (one end of a process-unit row) supported by the supporting frame  9  formed in such manner has a structure which is different from a structure of each of the other process units  6 B. In the following description, common points of the process units  6 A and  6 B will be described first, and structural difference will be described later. 
     The process unit  6  mainly includes a photosensitive-body unit  61  and a developing unit  62 . 
     The photosensitive-body unit  61  includes the photosensitive drum  61 A as an example of a photosensitive body, and a charger which is shown without a reference numeral in the diagram. 
     The developing unit  62  includes a developer container  62 A which accommodates a toner as an example of a developer, a developing roller  62 B, and components such as a supply roller and a layer-thickness regulating blade which are shown without a reference numeral. The developing unit  62  is detachable (separable) from the photosensitive-body unit  61 . 
     In the process unit  6 , a surface of the photosensitive drum  61 A charged by the charger is exposed by laser beam irradiated from the scanner section  5 , and an electric potential of an exposed portion thereof changes to form an electrostatic latent image on the photosensitive drum  62 A based on image data. Further, toner inside the developer container  62 A is carried to the developing roller  62 B via the supply roller, and the toner from the developing roller  62 B is supplied to the electrostatic latent image on the photosensitive drum  61 A, such that a toner image is supported on the photosensitive drum  61 A. 
     The transfer section  7  includes a transfer roller  71 , and components such as a drive roller, a driven roller, and a transporting belt which are shown without reference numerals in the diagram. 
     In the transfer section  7 , when the paper P transported by the transporting belt is fed between the photosensitive drum  61 A and the transfer roller  71 , the toner image on the photosensitive drum  61 A is drawn to the transfer roller  71 , and the toner image is transferred to the paper P. 
     The fixing section  8  includes a heating roller  81  and a press roller  82 . In the fixing section  8 , by forwarding the paper P while pinching the paper P between the heating roller  81  and the pressurizing roller  82 , the toner image on the paper P is fixed by heating. Moreover, the paper P on which the toner image is fixed is transported by the plurality of transporting rollers (reference numerals not assigned in the diagram) to a discharge tray  21  on the casing  2 . 
     The process unit  6 A at the extreme front side further includes a toner cartridge  63  as an example of a developer cartridge in addition to the developer container  62 A (first developer container). The toner cartridge  63  has a toner container  63 A (protruding portion, second developer container) in which toner is accumulated, and is detachable (separable) from an upper surface of the developer container  62 A. The developer container  63 A of the toner cartridge  63  and the developer container  62 A communicate with each other via openings  63 C and  62 C, which are opened and closed appropriately by shutters S 1  and S 2 . 
     Moreover, the toner cartridge  63  is installed at a frontward side on the upper surface of the developer container  62 A to be arranged on a front side of the scanner section  5 . Therefore, the developer container  63 A in the process unit  6 A at the extreme front side protrudes upward (toward the scanner section  5 ) than the other process units  6 B, to overlap with the scanner section  5  when viewed from the frontward and rearward direction. 
     More concretely, all the three process units  6 B at the inner side, and a part of the process unit  6 A at the extreme front side are constructed to be hidden under the scanner section  5 . Accordingly, a rear-side portion of the developer container  62 A of the developing unit  62  at the extreme front side and the developer containers  62 A of the three developing units  62  at the inner side are arranged to face the scanner section  5  in a vertical direction (direction orthogonal to the predetermined direction). Moreover, the toner cartridge  63  is connected to a front-side portion of the developer container  62 A of the developing unit  62  at the extreme front side, which is not facing the scanner section  5  in the vertical direction, to be arranged at a front side of the scanner section  5 . 
     Toner of black color which is used most frequently is accommodated in the developer containers  62 A and  63 A of the process unit  6 A at the extreme front side, which is formed to be larger in size than the other process units  6 B, and toners of cyan, magenta, and yellow colors are accommodated in the other three process units  6 B respectively. 
     Next, a structure of a front side of the casing  2  will be described below.  FIG. 2  is a side cross-sectional view showing the structure of the front side of the casing  2 . 
     An opening  2 A through which the process unit  6 A at the extreme front side is exposed to the front side and upper frontward side of the casing  2  is formed at a front side (one side in the arrangement direction of the process units  6 ) of the casing  2  as shown in  FIG. 2 . Moreover, the opening  2 A is opened and closed by an upper cover  22  and a front cover  23 . 
     The upper cover  22  is a cover having a shape of an English alphabet V in a cross-sectional view which forms an angular portion of the casing  2 . A rear portion of the upper cover  22  is pivotally supported by the casing  2 . Moreover, when a front portion of the upper cover  22  is lifted up, an upper side portion of the opening  2 A is opened, and the toner cartridge  63  faces an outside (upper frontward). Accordingly, the toner cartridge  63  is detachable from the upper side portion of the opening  2 A of the casing  2  in a state of being separated from the developing unit  62 . Moreover, the upper cover  22  is formed to be smaller than the front cover  23 . 
     The front cover  23  is a cover in the form of a flat plate also serving as a front panel of the casing  2 , and a lower portion thereof is pivotally supported by the casing  2 . Moreover, by lifting up the front portion of the upper cover  22  upward as described above and also bringing down by pulling frontward an upper portion of the font cover  23 , the opening  2 A is opened, and the process unit  6 A at the extreme front side is exposed to the outside (front side). Accordingly, the developing unit  62  at the extreme front side on which the toner cartridge  63  is mounted is detachable through the opening  2 A of the casing  2  in a state of being separated from the photosensitive-body unit  61 , and also the process unit  6 A at the extreme front side is detachable through the opening  2 A of the casing  2  separately from the other process units  6 B. 
     Next, a replacement job of components such as the toner cartridge  63  will be described below.  FIG. 3  is a side cross-sectional view showing a state in which a replacement job of the toner cartridge is performed, and  FIG. 4  is a side cross-sectional view showing a state in which a replacement job of the developing unit at the extreme front side is performed. Moreover,  FIG. 5  is a side cross-sectional view showing a state in which a replacement job of the process unit at the extreme front side is performed, and  FIG. 6  is a side cross-sectional view showing a state in which a replacement job of one of the three process units at the inner side is performed. 
     When the toner of black color in the process unit  6 A at the extreme front side is exhausted, as shown in  FIG. 3 , by opening only the upper cover  22 , a small opening (an upper side portion of the opening  2 A) is formed between a front end of the front cover  23  and a base end of the upper cover  22 . Thereafter, the toner cartridge  63  is detached from the developing unit  62 , and the developing unit  62  is taken out upward in a frontward direction from the small opening. Accordingly, only by opening the upper cover  22  and without opening the front cover  23 , it is possible to replenish the developing unit  62  at the extreme front side with the black color toner by replacing only the toner cartridge  63  accommodating the black color toner which is used most frequently. 
     Moreover, in a case of replacing the developing unit  62  at the extreme front side due to deterioration of a component (such as the developing roller  62 B) in the developing unit  62  at the extreme front side, firstly, the upper cover  22  and the front cover  23  are opened as shown in  FIG. 4 . Thereafter, the developing unit  62  at the extreme front side is detached from the photosensitive-body unit  61 , and the toner cartridge  63  and the developing unit  62  at the extreme front side are taken out together. Accordingly, it is possible to replace only the developing unit  62  at the extreme front side on which the toner cartridge  63  is mounted integrally. 
     Further, in a case of replacing the photosensitive-body unit  61  at the extreme front side due to deterioration of a component (such as the photosensitive drum  61 A) of the photosensitive-body unit  61  at the extreme front side, the upper cover  22  and the front cover  23  are opened as shown in  FIG. 5 . Thereafter, the process unit  6 A at the extreme front side is detached from the supporting frame  9 , and is taken out frontward. Accordingly, it is possible to replace the photosensitive-body unit  61  (the process unit  6 A) at the extreme front side, remaining the three process units  6 B at the inner side in the supporting frame  9 . 
     Moreover, in a case of replacing toner or a component in the three process units at the inner side, as shown in  FIG. 6 , the upper cover  22  and the front cover  23  are opened and the supporting frame  9  is pulled out frontward through the opening  2 A of the casing  2 . Thereafter, by detaching the process unit  6 B to be replaced similarly as described above, it is possible to replace toner and a component in the process unit  6 B. 
     According to the embodiment described above, an arrangement is made such that the process unit  6 A at the extreme front side protrudes upward than the other process units  6 B to overlap with the scanner section  5  when viewed from a frontward and rearward direction. Therefore, it is possible to secure a sufficient size of the developer containers  62 A and  63 A, without any of the process units  6 B interfering with the scanner section  5 . 
     Moreover, by accommodating the black color ink which is used more frequently in the developer containers  62 A and  63 A of the process unit  6 A at the extreme front side, it is possible to apply to the color laser printer  1  in which black-and-white printing is used substantially. 
     Since the process unit  6 A at the extreme front side is detachable from the other process units  6 B, and can be detachable with respect to the opening  2 A of the casing  2 , it is possible to replace only the process unit  6 A at the extreme front side accommodating the black ink which is used more frequently. 
     Since it is possible to detach the developing unit  62 A at the extreme front side through the opening  2 A of the casing  2 A by separating from the photosensitive-body unit  61 , it is possible to replace only the developing unit  62  at the extreme front side, while remaining leaving the photosensitive-body unit  61  which hasn&#39;t reached end of life in the casing  2 . 
     Further, since the toner cartridge  63  can be separated from the developing unit  62  and detached through the opening  2 A of the casing  2 , it is possible to replace only the toner cartridge  63  accommodating the black color toner which is used more frequently, while remaining the developing unit  62  which hasn&#39;t reached end of life in the casing  2 . 
     Moreover, since the supporting frame  9  which supports integrally the plurality of process units  6 , and which is detachable with respect to the casing  2  through the opening  2 A of the casing  2 , it is possible to replace any process unit  6  easily upon taking all process units  6  out of the casing  2  together. 
     Since the toner cartridge  63  is detachably provided to the front side portion (portion not facing the scanner section  5  in the vertical direction) on the upper surface of the developing unit  62  at the extreme front side, it is possible to attach and detach the toner cartridge  63  easily to and from the front side portion on the upper surface of the developing unit  62  exposing upward and frontward when the upper cover  22  is opened, thereby making the toner replacement job easy. If the developer container  62 A is made large in size by extending the upper portion of the developing unit  62  upward (when the developing unit  62  and the toner cartridge  63  are formed integrally), at the time of replacing the toner, it is necessary to remove the developing unit  62  integrated with the toner cartridge  63  by separating from the photosensitive-body unit  61 . Further, it is necessary to install upon positioning with the photosensitive-body unit  61  arranged under the scanner section  5  after replacing the toner. Therefore, the replacement job becomes complicated. However, by providing the toner ink cartridge  63  separately from the developing unit  62  in the embodiment, such complicated job becomes unnecessary. 
     Since it is possible to replace the toner cartridge  63  just by opening the upper cover  22  which is smaller than the front cover  23 , it is possible to carry out easily the job of replacing the black color toner which is required to be replaced frequently, without opening the front cover  23 . 
     The present invention is not restricted to the embodiment described above, and it is possible to use in various embodiments as exemplified below. In the embodiment, size of the developer container of the process unit  6 A is made large by connecting the developer container  63 A of the toner cartridge  63  which is a member different from the developer container  62 A of the developing unit  62 . However, the present invention is not restricted to such arrangement, and the developer container  62 A may be made large by extending the upper portion of the developing unit  62  upward. 
     In the embodiment, the direction of putting in and taking out the supporting frame  9  is made to be the frontward and rearward direction. However, the present invention is not restricted to such arrangement, and it may be a direction such as a vertical direction or a left-right direction. 
     Moreover, without providing the supporting frame  9 , each process unit  6  may be detachable from the casing  2 . 
     In the embodiment, the present invention is applied to the color laser printer  1 . However, the present invention is not restricted to be applied to a color laser printer, and may be applied to other image forming apparatuses such as a copying machine or a multi-function device. 
     In the embodiment, the photosensitive drum  61 A is used as a photosensitive body. However, the present invention is not restricted to such arrangement, and a photosensitive body in the form of a belt may also be used.