Abstract:
The developing device of the present invention has developer containers detachably to house developers to be supplied by hollow holding members, supports plural developing units to supply different color developers to an image carrier and plural developing units in the replaceable state, and a revolver to move a desired developing unit to a point opposite to the image carrier by rotating plural developing units en block, and openings of the holding members for inserting the developer containers in the holding members when removed.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present application is a continuation of U.S. application Ser. No. 10/370,495, filed Feb. 24, 2003, the entire contents of which are incorporated herein by reference.  
         [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a developing device for forming a color developing image using a revolver type developing device in such image forming apparatus as electro-photographic apparatus, printers, etc.  
         [0004]     2. Description of the Related Art  
         [0005]     In multi-color image forming apparatus equipped with plural developing units around a photosensitive drum, a multi-color image forming apparatus with a handle provided to each of developing units for removing them in the normal direction of developing sleeves is disclosed in Japanese Patent Publication No. 9-152757. However, this conventional multi-color image forming apparatus lacks a space for individually arranging plural developing units around a photosensitive drum and the downsizing is impeded.  
         [0006]     On the other hand, in order to achieve the downsizing, an image forming apparatus having plural developing units, for example, 3 developing units for supplying yellow (Y), magenta (M) and cyan (C) toners installed to a single revolving holder and further, a revolver type developing device to develop images formed on a photosensitive drum by rotating a revolving holder with a developing unit to supply black (BK) toner added by arranging developing units in prescribed color sequentially at an opposite position to a photosensitive drum are developed in recent years. This revolving type developing device is devised to achieve the further downsizing of the main body of an image forming apparatus by providing toner cartridges in the developing units.  
         [0007]     In this revolving type developing device, there is no space for installing handles, etc. for removing the developing units from the revolving holder. Therefore, when replacing the developing units during the maintenance, a serviceman removes developing units from a revolving holder by grasping the handle directly, etc. in a method easy to take out the developing unit carefully so as not to contaminate his hand.  
         [0008]     However, it is difficult to grasp a developing unit less handle and when removing developing units from a revolving holder, a worker may touch developing rollers and contaminate his hand or a developing unit may be dropped accidentally and damaged and further, the periphery may be contaminated by a developing unit when dropped and the operability may be deteriorated.  
         [0009]     Accordingly, it is so far desired to obtain a revolving type developing device that has the superior operability and high reliability by removing developing units from the revolving holder easily and safely without contaminating a hand and impeding the downsizing of the main body of the developing device.  
       SUMMARY OF THE INVENTION  
       [0010]     An object of the present invention is to remove developing units of a revolving type developing device easily and certainly from a revolving holder when replacing them by grasping them without contaminating a hand or dropping them and to improve the operability and reliability during the maintenance work.  
         [0011]     According to an embodiment of the present invention, a developing device comprising: plural developing units that have developer containers to house developers to be supplied detachably in a hollow holding member and supply different color developers to an image carrier and a revolver that supports the plural developing units in the replaceable state is provided and this developing device is capable of rotating the plural developing units en block to place a desired developing unit opposite to the image carrier; and is characterized in that the openings are formed on the holding member to insert the developer containers into the holding member when the developer containers are removed.  
         [0012]     Further, according to the embodiment of the present invention, an image forming apparatus comprising: an image carrier; a latent image forming unit to form a latent image on the image carrier; plural developing units having developer containers housing supply developers detachably by a hollow shaped holding member and supply developers in different colors to the image carrier; and a revolver provided rotatably in the main body of an apparatus, supports the plural developing units in the replaceable state and rotates the plural developing units en block to bring a desired developing unit to a point opposite to the image carrier, is characterized in that openings are formed on the holding members to insert the developing containers in the holding members when the developer containers are removed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a schematic diagram showing an image forming unit of an embodiment of the present invention;  
         [0014]      FIG. 2  is a perspective view for explaining the state of a revolver with a toner cartridge removed;  
         [0015]      FIG. 3  is an explanatory diagram showing a developing unit supported by a revolver in the embodiment of the present invention;  
         [0016]      FIG. 4  is a partial perspective view showing the slide movement of a toner cartridge from the main body of a developing unit in the embodiment of the present invention;  
         [0017]      FIG. 5  is a perspective view showing the state of the developing unit with a toner cartridge removed in the embodiment of the present invention;  
         [0018]      FIG. 6  is a partial perspective view showing the revolver in the state with the developing unit removed in the embodiment of the present invention;  
         [0019]      FIG. 7  is an explanatory diagram showing the state of the developing unit gripped by inserting the hand into the opening in the embodiment of the present invention; and  
         [0020]      FIG. 8  is a partial perspective view showing the state of the developing unit removed from the revolver in the embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     A preferred embodiment of the present invention will be described below in detail referring to the attached drawings.  FIG. 1  is a schematic construction diagram showing an image forming unit  10  of an image forming apparatus  8  such as color printers, etc. Around a photosensitive drum  11  that is an image carrier, of the image forming unit  10 , there are arranged a charger  12  for uniformly charging the photosensitive drum  11  following the rotation of the photosensitive drum  11  in the arrow direction s, a laser beam applying position  14  to apply a laser beam  13   a  from a laser wiring unit  13  that is a latent image forming unit  13  to form a latent image on the charged photosensitive drum  11 , a revolver  19  to support developing units  16 ,  17 ,  18  for developing images with yellow (Y), magenta (M) and cyan (C) developers so that they can rotate in the arrow direction t by a rotary holder  19   a , an intermediate transferring unit  21  that has an intermediate transferring belt  21   a  that is rotated in the arrow direction u, a cleaner  22  and a charge elimination lamp  23 .  
         [0022]     The laser writing unit  13  forms an electrostatic latent image on the photosensitive drum  11  by applying a laser beam  13   a  corresponding to each color writing signal according to image data that are input from external computer terminals, etc. The revolver  19  supports the developing units  16 - 18  so that they can be replaced by a rotary holder  19   a  that is rotated in the arrow direction t as shown in  FIG. 2 . The revolver  19  rotates the yellow (Y), magenta (M) and cyan (C) developing units  16 - 18  en bloc by rotating the rotary holder  19   a  in the arrow direction and then, moves desired developing units  16 - 18  to positions opposite to the photosensitive drum  11 . The developing units  16 - 18  are provided with developing devices  20 ,  21 ,  22  that have developing rollers  20   b - 22   b  and conveying augers  20   c - 22   c  to supply toners to electrostatic latent images on the photosensitive drum  11  in the developing containers  20   a - 22   a  as shown in  FIG. 3 .  
         [0023]     The developing units  16 - 18  are further provided with hollow shaped holders  16   a - 18   a . These holders  16   a - 18   a  retain toner cartridges  30 ,  31 ,  32  that are developer containers to house yellow (Y), magenta (M), cyan (C) toners to be supplied to the developing devices  20 - 22 . The toner cartridges  30 - 32  are fixed to the developing units  16 - 18  by locking claws  30   a - 32   a  attached to hooks  16   c - 18   c  as shown in  FIG. 4  and  FIG. 5 . The toner cartridges  30 - 32  are detachable from the holder  16   a - 18   a  by sliding to the front side of the main body  8   a  of the image forming apparatus  8 . At about the center of the outer surfaces of the holders  16   a - 18   a , openings  16   b - 18   b  are formed to communicate with the hollow inside of the holders  16   a - 18   a.    
         [0024]     In the revolver  19 , both ends of shafts  20   d - 22   d  of developing rollers  20   b - 22   b  are provided at a positioning portion  26  formed on the rotary holder  19   a  via bearings and hold the developing units  16 - 18  as shown in  FIG. 6 . At the positioning portion  26 , a developing unit fixing member  27  is rotatably mounted. To remove the developing units  16 - 18  from the revolver  19 , open the positioning portion  26  by removing a screw  27   a  and rotating the developing unit fixing member  27  in the arrow direction w. Move the developing units  16 - 18  from the revolver  19  in the direction right angle to the front side of the main body  8   a  of the apparatus.  
         [0025]     Next, the color image forming process by the image forming unit  10  will be described. In the image forming unit  10 , a color image is formed by superposing yellow (Y), magenta (M) and cyan (C) images in this order. When starting the image forming operation, the developing roller  20   b  of the yellow (Y) developing unit  16  is arranged at the developing position opposite to the photosensitive drum  11 .  
         [0026]     When the image forming process starts, the photosensitive drum  11  rotates in the arrow direction s and with this rotation, the photosensitive drum  11  is uniformly charged by the charger  12  and a laser beam corresponding to a yellow image signal is applied by the laser writing unit  13 . As a result, an electrostatic latent image of a yellow image is formed on the photosensitive drum  11  and when the drum reaches the developing unit  16 , a yellow (Y) toner image is formed.  
         [0027]     Then, the toner image formed on the photosensitive drum  11  reaches the contacting position with the intermediate transferring belt  21   a  that is rotated in the arrow direction u and primarily transferred electrostatically on the intermediate transferring belt  21   a . After the primarily transfer, the photosensitive drum  11  is cleaned and residual toner is removed by the cleaner  22  and the surface charger is eliminated by the charge elimination lamp  23 . Then, the magenta and cyan toner image forming processes are executed in the same manner as the yellow toner image forming process and magenta and cyan images for formed on the photosensitive drum  11 . Further, the yellow (Y), magenta (M) and cyan (C) toner images are transferred intermediately on the intermediate transferring belt  21   a  from the photosensitive drum  11  and a color toner superposed with 3 color images is formed on the intermediate transferring belt  21   a    
         [0028]     While the revolver  19  turns in the arrow direction t, it arranges the developing units  16 - 18  opposite to the photosensitive drum  11  corresponding to colors of toner images to be formed on thereon. The yellow (Y), magenta (M), cyan (C) color toner images superposed on the intermediate transferring belt  21   a  are secondarily transferred en bloc on a recording paper, etc. and a color image is completed thereon.  
         [0029]     While the image forming process is thus repeated, carriers are deteriorated when a prescribed number of sheets, for example, 50,000 A4 size sheets are printed and it becomes necessary to exchange developers in the developing units  20 - 22  or replace the developing units  16 - 18  with new products. To remove the developing units  16 - 18  from the revolver  19  for executing the replacing maintenance of developers or the developing units  16 - 18 , it is first necessary to remove toner cartridges  30 - 32  from the revolver  19  in order to remove the toner cartridges  30 - 32  from the developing units  16 - 18 , rotate the revolver in the arrow direction t to the toner cartridges  30 - 32  replacing position.  
         [0030]     Fix the revolver  19  at the replacing position of the toner cartridges  30 - 32 , remove the locking claws  30   a - 32   a  from the hooks  16   c - 18   c . Remove the toner cartridges  30 - 32  from the holders  16   a - 18   a  by sliding them in the arrow direction x shown in  FIG. 4 , that is, in the front side direction of the main body  8   a  of the image forming apparatus. When the toner cartridges  30 - 32  are removed from the holders  16   a - 18   a , the insides of the holders  16   a - 18   a  become empty and it becomes possible to insert a hand  28  from the openings  16   b - 18   b.    
         [0031]     Then, rotate the revolver  19  in the arrow direction t to the replacing position of the developing units  16 - 18 . At the replacing position of the developing units  16 - 18 , fix the revolver  19 , remove the screw  17   a  of the developing unit fixing member  27  of the revolving holder  19   a  and open the positioning portion  26  by rotating the developing unit fixing member  27  in the arrow direction w. A serviceman should insert his hand  28  in the empty insides of the holders through the openings  16   b - 18   b  of the holders  16   a - 18   a , grip each of the developing units  20 - 22  and pull out the developing units  16 - 18  in the arrow direction y that is the right angle to the front side of the main body  8   a  of the image forming apparatus shown in  FIG. 7  and  FIG. 8 , and take out the developing units  16 - 18  from the revolver  19 .  
         [0032]     Thereafter, exchange developers in the developing units  20 - 22  or exchange the developing units  16 - 18  with new units as required and install the developing units  16 - 18  to the revolver  19 . When installing the developing units  16 - 18 , grip the developing units  20 - 22  by inserting the hand in the openings  16   b - 18   b  and install both ends of shafts  20   d - 22   d  of the developing rollers  20   b - 22   b  to the positioning portion  26 .  
         [0033]     Further, fix the developing unit fixing member  27  with the screw  27   a . Then, rotate the revolver  19  in the arrow direction t to the replacing position of the toner cartridges  30 - 32 , install the toner cartridges  30 - 32  to the holders  16   a - 18   a , put the locking claws  30   a - 32   a  to the hooks  16   c - 18   c . The exchange maintenance of the developing units  16 - 18  is now completed and the image forming process is ready to start.  
         [0034]     According to this embodiment, when the toner cartridges  30 - 32  are removed from the developing units  16 - 18  in the exchanging maintenance of the developing units  16 - 18 , the insides of the holders  16   a - 18   a  become empty and it becomes possible to insert the hand  28  in the empty insides through the openings  16   b - 18   b  formed on the holders  16   a - 18   a . Accordingly, when exchanging the developing units  16 - 18  with new units, it is possible to remove the developing units  16 - 18  from the revolver  19  by gripping the developing units  20 - 22  firmly and moving in the right angle direction to the front side of the main body  8   a  of the image forming apparatus  8 . In other words, the developing units  16 - 18  can be exchanged certainly and rapidly without contaminating a hand by touching the developing rollers  20   b - 22   b , and damaging the developing units  16 - 18  and contaminating the periphery by dropping them accidentally and improving the maintainability and reliability.  
         [0035]     Further, the present invention is not limited to the embodiment described above but can be modified variously within the spirit and scope of the present invention and for example, colors of developers of the developing units supported by the revolver are not limited and the number of developing units supported by the revolver can be increased to 4 units by adding a developing unit containing black toner. In addition, the structure of the image forming apparatus is optional and it is possible to obtain a full-color image by providing a developing unit containing, for example, black toner separately from the revolver around the image carrier.  
         [0036]     As described above, according to the present invention, the openings are formed in the holding members and by removing the developer containers first from the holding members when exchanging the developing units, it becomes possible to remove a developing unit by firmly gripping the opening from the revolver. Accordingly, the operability during the exchanging maintenance of the developing units can be improved, contamination of the hand and periphery by developers and damage of the developing units by accidentally dropping them and the maintainability and reliability can be improved.