Abstract:
A method of assembling a developing apparatus comprises, forming a recess in the outer circumference of a pair of holding members, fitting a first positioning pin of an adjustment jig into the recess without a clearance, after the fitting, fitting a concave support member on a second positioning pin without a clearance, and positioning and mounting them, after the fitting, separating the first and second positioning pins of the adjustment jig from the recess and the support member, after the separation, assembling a pair of holding members in one body with a predetermined interval, and after the assembly, mounting a plurality of developing rollers by fitting both ends of the center shaft into the recess of the pair of holding members and the concave support member, respectively.

Description:
[0001]     The present application is a continuation of U.S. application Ser. No. 10/383,662, filed Mar. 10, 2003, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to a method of assembling a color developing apparatus provided in an electrophotographic copier, for example.  
         [0003]     Some developing apparatuses of this type have a rotatable holding unit and a plurality of developing units arranged over the rotating direction of the holding unit.  
         [0004]     Each of the plurality of developing units contains a different color toner and has a developing roller. These developing units are sequentially moved to the developing position by the rotation of the holding unit. An electrostatic latent image formed on a photoconductor is moved to the developing position by the rotation of the photoconductive element. A first color toner is supplied to the latent image by the rotation of the developing roller, and a first color toner image is formed. The toner image is transferred to an intermediate transfer unit, for example.  
         [0005]     After the first color toner image is formed, the holding unit rotates, the developing unit is moved to the developing position, and a second color toner image is formed on the photoconductive element. The second color toner image is transferred over the first color toner image on the intermediate transfer unit. Toner images of the other colors are sequentially formed in the same manner, transferred over the toner image on the intermediate transfer unit, and a full-color image is formed and transferred to paper.  
         [0006]     It is necessary for preferable development to set the developing roller and photoconductor parallel to one another.  
         [0007]     Thus, in the prior art, a plurality of recesses is formed in the circumference of the side plates of the front and rear sides of a holding unit, over the circumferential direction, and a developing roller is mounted by fitting both ends of its center shaft into a recess.  
         [0008]     A holding unit has to be made by press work when the material of its side plate is sheet metal, and by injection molding when the material is plastic. In either case, a precision mold must be used.  
         [0009]     However, considering the precision of a producible mold, later press work and injection molding accuracy, it is difficult to make the recesses with the theoretically demanded positioning accuracy, and it becomes impossible to produce a good image.  
         [0010]     Thus, clamping an optional concave support member to the circumference of a pair of side plates of a holding unit over its rotating direction by means of a plurality of screws, and fitting through a bearing both ends of the center shaft of a developing roller to the support members of the pair of side plates has been considered.  
         [0011]     In this case, it is possible to position the concave support members by a jig, and it is also possible to ensure the positioning accuracy of the support members by increasing the positioning accuracy of the jig.  
         [0012]     However, in the prior art, since all optional support members are positioned by a jig, it is possible to ensure the relative positioning accuracy of the jig and support members, but the positioning accuracy is lowered between the side plate and support members.  
         [0013]     Thus, when the front and rear side plates are made in one body by connecting them through a shaft and a stay member and a developing roller is provided between these side plates, there arises a problem that a twist is generated before and after the holding unit and it becomes difficult to keep a developing roller and an image holding member parallel.  
       BRIEF SUMMARY OF THE INVENTION  
       [0014]     The present invention has been made in order to solve the above problems. It is an object of the present invention is to provide a method of assembling a developing apparatus which can keep a developing roller and an image holding member parallel without twisting a holding unit.  
         [0015]     According to an embodiment of the present invention, there is provided a method of assembling a developing apparatus comprising, forming a recess in the outer circumference of a pair of holding members; preparing an adjustment jig having a first positioning pin and a second positioning pin, and fitting the first positioning pin of the adjustment jig into the recess without a clearance; after the fitting, fitting a concave support member on the second positioning pin without a clearance, and positioning and mounting them on the outer circumference of the holding member; after the fitting, separating the first and second positioning pins of the adjustment jig from the recess and the support member; after the separation, assembling the pair of holding members in one body with a predetermined interval; and after the assembly, mounting a plurality of developing rollers by fitting both ends of the center shaft into the recess of the pair of holding members and the concave support member, respectively.  
         [0016]     According to another embodiment of the present invention, there is provided a method of assembling a developing apparatus comprising, forming a first recess and a second recess in the outer circumference of a pair of holding members over its rotating direction; preparing an adjustment jig having a first positioning pin and a second positioning pin, and fitting the first positioning pin of the adjustment jig into the first recess without a clearance, and fitting the second position pin into the second recess with a clearance; after the fitting, fitting a first concave support member on the first positioning pin, and fitting a second concave support member on the second positioning pin without a clearance, and positioning and mounting them on the outer circumference of the holding member; after the mounting, separating the first and second positioning pins of the adjustment jig from the first and second support members; after the separation, assembling the pair of holding members in one body with a predetermined interval; and after the assembly, mounting a plurality of developing rollers by fitting both ends of the center shaft into the first recess of the pair of holding members and the second concave support member, respectively.  
         [0017]     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.  
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0018]     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.  
         [0019]      FIG. 1  is schematic diagram showing an internal structure of a color electrophotographic copier according to one embodiment of the present invention;  
         [0020]      FIG. 2  is a perspective view showing a holding unit in  FIG. 1 ;  
         [0021]      FIG. 3  is a magnified perspective view of a support member of a rotor of the front side of the holding unit in  FIG. 2 ;  
         [0022]      FIG. 4  is a magnified perspective view of a support member of a rotor of the rear side of the holding unit in  FIG. 2 ;  
         [0023]      FIG. 5  is a front view showing a positioning pin of an adjustment jig, fitting into the recess of a rotor of the holding unit;  
         [0024]      FIG. 6  is a magnified front view of the recess of the rotor of  FIG. 5 , fitting on the positioning pin of the adjustment jig;  
         [0025]      FIG. 7  is a magnified front view of the recess of the rotor of  FIG. 5 , fitting on the positioning pin of the adjustment jig;  
         [0026]      FIG. 8  is a magnified front view of the recess of the rotor of  FIG. 5 , fitting on the positioning pin of the adjustment jig;  
         [0027]      FIG. 9  is a front view of the rotor of  FIG. 5  equipped with an adjusting sheet metal and a holder bracket;  
         [0028]      FIG. 10  is a perspective view of the rotor of  FIG. 5  with the adjustment jig removed;  
         [0029]      FIG. 11  is a perspective view showing the rotor of  FIG. 10  assembled, and a first developing unit to be equipped to the rotors; and  
         [0030]      FIG. 12  is a perspective view of the rotor of  FIG. 11  equipped with a first developing unit. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]     Hereinafter, the present invention will be explained in detail by referring to the embodiments shown in the attached drawings.  
         [0032]      FIG. 1  is schematic diagram showing an internal structure of a color electrophotographic copier according to one embodiment of the present invention.  
         [0033]     In the drawing, a reference numeral  1  denotes a rotary drum photoconductor as an image holding member. On the circumference of the photoconductor  1 , an electrifying charger  2 , an exposure unit  4  as an electrostatic latent image forming device, a monochrome developing unit  5 , a color developing unit  6 , an intermediate transfer member  8 , a cleaning unit  9  and a de-electrifying charger  10  are arranged along the drum rotating direction (indicated by an arrow). A transfer roller  11  is arranged opposite to the intermediate transfer member  8 .  
         [0034]     The electrifying charger  2  electrifies the surface of the photoconductor  1 , and the exposure unit  4  forms an electrostatic latent image on the surface of the photoconductor  1 . The developing units  5  and  6  develop an electrostatic latent image. The intermediate transfer member  8  temporarily transfers a toner image on the photoconductor  1 , and the transfer roller  11  transfers a toner image on the intermediate transfer member  8  to paper P. The cleaning unit  9  eliminates residual toner on the photoconductor  1 . The de-electrifier  10  de-electrifies the surface of the photoconductor  1 .  
         [0035]     The color developing unit  6  has a rotatable holding unit  15 , and the rotatable holding unit  15  holds first to third developing units  6 A,  6 B and  6 C over its rotating direction.  
         [0036]     The first developing unit  6 A contains yellow toner, and has a developing roller  6   a  which supplies the yellow toner. The second developing unit  6 B contains magenta toner, and has a developing roller  6   b  which supplies the magenta toner. The third developing unit  6 C contains cyan toner, and has a developing roller  6   c  which supplies the cyan toner.  
         [0037]     Next, the image forming process will be explained.  
         [0038]     First, the surface of the photoconductor  1  is electrified by the electrifying charger  2 , image information light is radiated from the exposure unit  4  onto the surface of the electrified photoconductor  1 , and an electrostatic latent image is formed. In color development, the electrostatic latent image is sent to the developing position opposite to the first developing unit  6 A by the rotation of the photoconductor. At this position, the yellow toner is supplied to the electrostatic latent image by the rotation of the developing roller  6   a , and the image is developed. The yellow toner image is transferred to the intermediate transfer member  8 .  
         [0039]     After the transfer operation, the toner remaining on the photoconductor  1  is eliminated by the cleaning unit  9 , and the surface of the photoconductor  1  is electrified again. Image information light is radiated from the exposure unit  4  onto the surface of the charged photoconductor  1 , and an electrostatic latent image is formed.  
         [0040]     The electrostatic latent image is sent to the developing position by the rotation of the photoconductor  1 , but before the latent image reaches the developing position, the second developing unit  6 B is moved to the developing position by the rotation of the holding unit  15 . When the electrostatic latent image reaches the developing position, toner (magenta) of a different color from the first color (yellow) is supplied, and a second color toner image is formed.  
         [0041]     The second color toner image is transferred over the first color toner image on the intermediate transfer member  8 . Thereafter, the third color toner image is formed on the photoconductor  1 , and transferred over the image on the intermediate transfer member  8 , and a color image is formed. The color image is collectively transferred to the paper P by the transfer roller  11 .  
         [0042]     The paper P with transferred color image is carried to a fixing unit not shown in the drawing, where it is heated and pressurized, and the color image is fixed to the paper P.  
         [0043]      FIG. 2  is a perspective view showing the holding unit  15  holding the first developing unit  6 A of  FIG. 1 .  
         [0044]     The holding unit  15  has rotors  16 A and  16 B as a holding member in its front and rear sides. The rotors  16 A and  16 B are connected and assembled in one body through a shaft  17  as a connecting member. On the circumference of the rotors  16 A and  16 B, first to third recesses  18   a ,  18   b  and  18   c  are formed at regular intervals over its rotating direction.  
         [0045]     The rotors  16 A and  16 B are equipped with first to third concave adjusting sheet metals  19   a - 19   c  adjoining the first to third recesses  18   a - 18   c , as shown in  FIG. 3  and  FIG. 4 .  
         [0046]     The first recess  18   a  functions as a support member for supporting both ends of a center shaft  20   a  of the developing roller  6   a . The second and third adjusting sheet metals  19   b  and  19   c  function as support members for supporting both ends of the center shafts  20   b  and  20   c  of the developing rollers  6   b  and  6   c.    
         [0047]     The first to third adjusting sheet metals  19   a - 19   c  are rotatively provided with holder brackets  21   a - 21   c  holding both ends of the center shafts  20   a - 20   c  of the first to third developing rollers  6   a - 6   c.    
         [0048]     Description will now be given on the method of assembling the above-mentioned holding unit  5  based on  FIG. 5 - FIG. 12 .  
         [0049]     First, prepare an adjustment jig  23  which is provided with a center pin  24  and first to third positioning pins  25   a ,  25   b  and  25   c  projecting on a base plate. The outer diameters of the first to third pins  25   a ,  25   b  and  25   c  are almost the same as the outer diameters of the bearings at both ends of the center shafts  20   a - 20   c  of the first to third developing rollers  6   a - 6   c.    
         [0050]     Insert the center pin  24  of the adjustment jig  23  into the center hole  26  of a rotor  16 A ( 16 B), and fit the first to third positioning pins  25   a - 25   c  into the thirst to third recesses  18   a  to  18   c . The first recess  18   a  fits on the first positioning pin  25   a  without a clearance, as shown in  FIG. 6 , and the second and third recesses  18   b  and  18   c  fit on the second and third positioning pins  25   b  and  25   c  with a clearance, as shown in  FIG. 7  and  FIG. 8 .  
         [0051]     Thereafter, as shown in  FIG. 9 , fix the first to third adjusting sheet metals  19   a - 19   c  and the holder brackets  21   a - 21   c  to the rotor  16 A ( 16 B), as shown in  FIG. 9 , and fit these first to third adjusting sheet metals  19   a - 19   c  on the first to third positioning pins  26   a - 25   c.    
         [0052]     At this time, the first positioning pin  25   a  is fitted in the first adjusting sheet metal  19   a  with a clearance, and the second and third positioning pins  25   b  and  25   c  are fitted in the adjusting sheet metals  19   b  and  19   c  without a clearance.  
         [0053]     After fixing the first to third adjusting sheet metals  19   a - 19   c  and holder brackets  21   a - 21   c , as described above, remove the adjustment jig  23  as shown in  FIG. 10 .  
         [0054]     Thereafter, as shown in  FIG. 11 , connect a pair of rotors  16 A ( 16 B) through the shaft  17  as a connecting member, and assemble them as a single unit. Then, fit both ends of the center shaft  20   a  of the developing roller  6   a  of the first developing unit  6 A with the first recess  18   a  of the rotors  16 A and  16 B of the front and rear sides without a clearance through the bearing  28   a . Then, fit both ends of the center shafts  20   b  and  20   c  of the second and third developing rollers  6   b  and  6   c , in the second and third adjusting sheet metals  19   b  and  19   c  through the bearing.  
         [0055]     After assembling as described above, rotate the holder brackets  21   a - 21   c  upward and close them, and hold the bearing at both ends of the center shafts  20   a - 20   c , and fix the first to third developing units  6 A- 6 C, as shown in  FIG. 12 .  
         [0056]     As explained above, according to this embodiment, the recess  18   a  is directly formed in the rotor  16 A ( 16 B), the first positioning pin  25   a  of the adjustment jig  23  fitted into this recess  18   a  of the rotor  16 A ( 16 B) without a clearance, and the second and third adjusting sheet metals  19   b  and  19   c  fitted to the second and third positioning pins  25   b  and  25   c  of the adjustment jig  23  without a clearance. Thus, it is possible to increase the positioning accuracy of the second and third adjusting sheet metals  19   b  and  19   c  with respect to the rotor  16 A ( 16 B), and the parallelism between the developing rollers  61 - 6   c  and the photoconductor  1 .  
         [0057]     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.