Abstract:
A developer cartridge is used with an image forming apparatus. The developer cartridge has a groove which formed in a longitudinal end surface of thereof and extends in an insertion direction of the cylinder. A strip-shaped projection formed in the image forming apparatus projects extends in the insertion direction. When the developer cartridge is fully inserted into the image forming apparatus, the groove receives the projection so that the projection is at a predetermined position relative to the developer cartridge. Two first walls define the groove which is progressively wide as the circumference is approached. A second wall rises from the longitudinal end surface of the developer cartridge and is continuous with one of the two first opposed walls. The second wall smoothly guides the projection into the groove.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is divisional of U.S. application Ser. No. 09/178,694 filed Oct. 26, 1998. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a developer cartridge which is cylindrical in shape and fits to a projection formed on a cartridge receiving section, thereby being received in an image forming apparatus. 
     DESCRIPTION OF THE RELATED ART 
     A developer cartridge is a consumable item which is loaded into an image forming apparatus and supplies toner to the image forming apparatus. FIG. 10A illustrates a conventional cylindrical developer cartridge when it is attached to the image forming apparatus. FIG. 10B is a fragmentary cross-sectional view of a cartridge receiving section. 
     A cylindrical developer cartridge  100  holds developer toner, not shown, therein, and supplies toner to an image forming apparatus when the developer cartridge  100  is loaded in a cartridge-receiving section of the image forming apparatus  200 . The cartridge  100  is formed with a groove  100   a  in a longitudinal end surface thereof. A cartridge receiving section  200   a  has a tapered projection  200   b.    
     When loading the cartridge  100  into the cartridge receiving section  200   a , the cartridge  100  is lowered in a direction shown by arrow A so that the projection  200   b  enters the groove  100   a . The tapered shape of the projection  200   b  serves to properly guide the projection  200   b  into the groove  100   a  so that the cartridge  100  is smoothly received into the cartridge receiving section  200   a.    
     The width of the groove  100   a  is only slightly greater than that of the projection  200   b . Therefore, if the cartridge  100  is inserted into the cartridge receiving section with the groove  100   a  laterally offset from the projection  200   b , the tapered shape of projection  200   b  is not effective enough in guiding the cartridge  100  into the cartridge receiving section  200   a.    
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a developer cartridge and an image forming apparatus where the developer cartridge can be loaded without difficulty. 
     A developer cartridge is used with an image forming apparatus. The cartridge is in the shape of a cylinder. The cylinder extends in a longitudinal direction and has a groove formed in a longitudinal end surface of the cylinder. The groove generally extends in an insertion direction of the cylinder in which the cartridge is inserted into the image forming apparatus, and receives a projection formed in the image forming apparatus when the cartridge is inserted into the image forming apparatus. The projection projects in the longitudinal direction and extends in the insertion direction. The groove guides the projection to a predetermined position relative to the cartridge when the cartridge is fully inserted into the image forming apparatus. Two first walls define the groove therebetween so that the groove tapers in width towards the center of the cylinder. The first walls oppose each other and are at an angle with the insertion direction of the cartridge so that the groove is progressively wide with increasing distance from a center of the cylinder. A second wall rises from the longitudinal end surface of the cartridge and is continuous with one of the two first opposed walls. 
     The cartridge has a circumferentially curved wall. The projection extends in the insertion direction and has a forward end and rearward end. The rearward end is substantially configured to the inner surface of the circumferentially curved wall. 
     The cartridge includes a third wall which rises from the longitudinal end surface and is continuous with said second wall. The third wall extends substantially parallel to the insertion direction and slidingly engaging the projection when the cartridge is fully inserted into the image forming apparatus. 
     The projection tapers at its forward half to correspond to the width of the groove at a distance away from the center of the cylinder since the groove tapers in width toward the center of the cylinder. In this way, the projection will not completely project into the groove unless it is a predetermined distance away from the center of the cylinder. 
     The groove has a bottom surface beveled so that the groove is deeper near the circumference of the cylinder at its forward half with decreasing distance from a center of the cylinder. The projection projects less with decreasing distance from a center of the cylinder. 
     The groove has a bottom surface beveled so that the groove is progressively deep with increasing distance from a center of the cylinder or as the circumference is approached. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
     FIG. 1 is an enlarged perspective view of a developer cartridge according to a first embodiment of the invention; 
     FIG. 2 is a general perspective view of an image forming apparatus according to the first embodiment; 
     FIG. 3A is an illustrative diagram showing a mounting construction of the developer cartridge of the first embodiment; 
     FIG. 3B is a cross-sectional view of the mounting construction taken along lines K—K of FIG. 3A; 
     FIGS. 4A-4B illustrate the loading operation of the developer cartridge of the first embodiment; 
     FIG. 5 is an enlarged view of a developer cartridge according to a second embodiment; 
     FIG. 6 is an illustrative diagram with a partial cutaway view, showing the loading of the cartridge into an image forming apparatus; 
     FIG. 7A is a partial perspective view of a mounting construction according to a second embodiment; 
     FIG. 7B is a partial cross-sectional view of the mounting construction and the image forming apparatus according to the second embodiment; 
     FIG. 7C is an illustrative diagram showing a mounting construction of a developer cartridge according to the second embodiment; 
     FIGS. 8A-8C are illustrative diagrams showing the procedure of loading the developer cartridge of the second embodiment; 
     FIG. 9 shows examples of drawbacks when an inappropriate developer cartridge is accidentally inserted into the image forming apparatus according to the second embodiment; 
     FIG. 10A illustrates a conventional developer cartridge when it is loaded into the image forming apparatus; and 
     FIG. 10B is a partial cross-sectional side view of the cartridge receiving section. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be described in detail with reference to the drawings. 
     First Embodiment 
     FIG. 1 is an enlarged perspective view of a developer cartridge according to a first embodiment of the invention. FIG. 2 is a general perspective view of an image forming apparatus according to the first embodiment. 
     A developer cartridge  1  is generally in the form of a cylinder and holds developer toner, not shown. The developer cartridge  1  has a mounting construction  2  by which the developer cartridge  1  is loaded into an image forming apparatus  20  shown in FIG.  2 . The mounting construction  2  is formed with a groove  3  in a longitudinal circular end surface  2 A thereof, the groove  3  radially extending and opening to a circumferential edge  3   a  of the cylindrical developer cartridge  1 . The image forming apparatus  20  has a cartridge receiving section  21  in which the developer cartridge  1  is received. The cartridge receiving section  21  has a strip-like projection  22  which has an upwardly tapered tip  22   a.    
     The shape of the groove  3  will be described with reference to FIGS. 3A-3B and  4 A- 4 B. The groove  3  is defined by two opposing wall surfaces  3   c  and  3   d  and a beveled bottom  3   a . Wall surface  3   c  and is continuous with a guide wall  4  which rises from the longitudinal end surface  2 A and has first and second surfaces  4   a  and, respectively. The surface  4   b  extends in a direction of insertion of the cartridge  1  while the surface  4   a  extends in such a direction as to widen the groove  3  with increasing distance away from the center of the end surface  2 A. In other words, the groove  3  tapers toward the center of the end surface  2 A so that the groove  3  progressively narrow toward the center of the circular longitudinal end surface  2 A. The surface  4   a  makes an angle of θ1 with the direction of insertion A of the projection  22 . The angle θ1 is preferably larger than a taper angle of the tip  22   a  of the projection  22   a  and less than the taper angle of the tip  22   a  plus 30 degrees. 
     After having been fully inserted into the cartridge receiving section, the cartridge  1  is rotated through a predetermined angle θ2 with the projection  22  engaging the longitudinal end surface  2 A, thereby being completely loaded into the cartridge receiving section  20 . The mounting construction  2  has a wall  5  which rises from the longitudinal end surface  2 A and extends radially. The wall  5  has a stopper surface  5   a  which abuts the projection  22  to limit the rotation of the developing cartridge  1  when the cartridge  1  is rotated by the predetermined angle. The mounting construction  2  also has a circumferential wall  6  which tapers toward its free end near the groove  3 . When the cartridge  1  has been completely received in the cartridge receiving section  20 , the tip portion  22   a  of the projection  22  extends into a space between the surface  4   b  and the stopper surface  5   a . A part of the groove  3  near the surface  4   a  is wider than the width W of the projection  22 , so that there is a sufficient clearance between the projection  22  and the surface  4   a  for smooth advancement of the projection  22  into the space between the surface  4   a  and the stopper surface  5   a.    
     The surface  4   b  extends over a distance longer than the width W of the projection  22 . The distance is an experimentally determined value such that when the projection  22  has passed through the groove  3  into contact engagement with the longitudinal end surface  2 A, the surface  4   b  engages the projection  22  to support the cartridge  1  in a stable position. The distance longer than the width W is necessary in order to support the projection  22  when the cartridge  1  is rotated with the projection  22  at the position shown in FIG.  3 A. 
     The operation for loading the developer cartridge  1  according to the first embodiment into the cartridge receiving section  20  will be described with reference to FIGS. 3A-3B and  4 A- 4 B. 
     The user holds the developer cartridge  1  with the mounting construction  2  directly above the projection  22 . Then, the cartridge  1  is lowered in the insertion direction shown by arrow A. If the cartridge  1  is slightly laterally offset from the projection  22 , then the surface  4   a  abuts the tip  22   a  of the projection  22 . The cartridge  1  is then guided by the tip  22   a  in such a way that the tip  22   a  advances toward the space between the surface  4   b  and the stopper surface  5   a . At this time, the bottom  3   a  of the groove  3  is also helpful in guiding the cartridge  1 . When the tip  22   a  enters the space between the surface  4   b  and the stopper surface  5   a , the insertion of the cartridge is completed. 
     Then, the user rotates the developer cartridge  1  in a direction shown by arrow C in FIG.  3 A. After having rotated through the predetermined angle θ2, the projection  22  abuts the stopper surface  5   a  to prevent the cartridge  1  from further rotation. This completes the loading operation of the cartridge  1 . 
     When removing the developer cartridge  1  from the image forming apparatus, the above mentioned procedure can be performed in the reverse order. 
     Second Embodiment 
     The developer cartridge according to a second embodiment has a surface that corrects the position of a developer cartridge when the developer cartridge is inserted with its position offset from the correct position. 
     The second embodiment will be described with reference to FIGS. 5,  6 , and  7 A- 7 B. 
     A developer cartridge  50  holds developer toner, not shown, just as in the first embodiment. The cartridge  50  has a mounting construction  51  via which the cartridge  50  is loaded into the image forming apparatus  60 . The mounting construction  51  has a groove  52  formed therein that extends radially outwardly and opens to the circumferential edge  52   b  of the mounting construction  51 . The groove  52  has a beveled bottom  52   a  such that the groove  52  is deepest nearer as the circumference edge  52   b.    
     The image forming apparatus  60  has a cartridge receiving section  61  similar to the cartridge receiving section  21  of the first embodiment. The cartridge receiving section  61  has a projection  62  (FIG. 8A) in place of the projection  22  of the first embodiment. The projection  62  differs from the projection  22  in that the projection  62  has a base  62   b  which has an arcuate end surface  62   f . The base  62   b  has a width W′ larger than the width W of the projection  62 . The projection  62  and base  62   b  project from the cartridge receiving section  61 . The projection  62  has a beveled surface  62   e  substantially complementary with the surface  53   a  of an arcuate wall  53  of cartridge  50 . 
     FIG. 7A is a fragmentary perspective view of the mounting construction  51 . 
     FIG. 7B is a cross-sectional side view of the cartridge receiving section  61  and cartridge  50 . 
     The groove  52  of the mounting construction  51  will be described with reference to FIG.  7 A. The mounting construction  51  has a guide wall  54  which rises from the longitudinal end surface  51 A and includes first, second and third surfaces  54   b ,  54   a  and  54   c , respectively, and a stopper wall  55  having a stopper surface  55   a  which rising from the longitudinal end surface  51 A. The surface  54   c  and the surface  54   a  extend in directions substantially parallel to a direction of insertion shown by arrow A, but are offset from each other. The surface  54   c  extends over a distance longer than the width W of the narrow projection  62  for the same reason as in the first embodiment. The surface  54   b  makes an angle α with the direction of insertion shown by arrow A of the cartridge in such a way that the surface  54   b  widens the groove  52  with increasing distance from the center of the circular longitudinal end surface  51 A of the cartridge  50 . In other words, the groove  52  tapers radially inwardly. The angle a is preferably the same as the angle θ2 in the first embodiment. The circumferential wall  53  also rises from the end surface  51 A and tapers toward its free end near the groove  52 . 
     The cartridge  50  is placed in the cartridge receiving section  61  with the projection  62  fitting into the groove  52 . Then, the cartridge is rotated in a direction shown by arrow C. This completes the loading of the cartridge  61 . The arcuate surface  62   f  smoothly slides on the inner surface of the circumferential wall  53 , allowing the cartridge  50  to rotate smoothly. When the cartridge  61  is rotated through a predetermined angle θ2, the stopper surface  55   a  of wall  55 , abuts the projection  62  to prevent further rotation of the cartridge  50 . The stopper surface  55   a  is configured to the contour or outline of the projection  62  and base  62   b  and therefore not flat so that the stopper surface  55   a  is complementary to the projection  62 . 
     A space between the surface  54   c  and the stopper surface  55   a  is such that only the narrow projection  62  having a width W can loosely fit. The width of the groove  52  near the circumference of the cylindrical cartridge  50  is slightly larger than the width of the base  62   b.    
     The rest of the construction is the same as that of the first embodiment and the description thereof is omitted. 
     FIGS. 8A-8C are illustrative diagrams showing the procedure of loading the developer cartridge of the second embodiment 
     The loading operation of the developer cartridge will be described with reference to FIGS. 8A-8B and  9 . 
     The user holds the cartridge  50  with the mounting construction  51  directly above the projection  62 . Then, the cartridge is lowered in the direction shown by arrow A so that the projection  62  enters the groove  52 . The beveled surface  62   e  cooperates with the beveled surface  52   a  of the cartridge  50  in such a way that one surface slides over the other for smooth insertion of the projection  62  into the groove  52 . If the tip  62   a  of the projection  62  abuts the surface  54   a  or  54   b , the surface corrects the insertion direction of the cartridge  50  projection  62  so that the cartridge  50  is properly guided by the projection  62 . Thus, the tip  62   a  smoothly enters the space between the surface  54   c  and stopper surface  55   a.    
     When the tip  62   a  enters the space between the surface  54   c  and the stopper surface  55   a  and the base  62   b  abuts the surface  54   b , the cartridge has been completely inserted as shown in FIG.  8 B. The projection  62  is configured to the shape of the wall  54 . 
     Then, the user rotates the cartridge  50  in a direction shown by arrow C just as in the first embodiment. After the cartridge has been rotated through a predetermined angle θ2, the stopper surface  55   a  abuts the projection  62 , thereby limiting the a further rotation of the cartridge. This completes the loading of the cartridge. 
     When removing the developer cartridge  50  from the image forming apparatus, the above mentioned procedure can be performed in the reverse order. 
     FIG. 9 shows a drawback, by way of example, when an inappropriate developer cartridge is accidentally inserted into the image forming apparatus according to the second embodiment. 
     The second embodiment is advantageous in that if a user attempts to load a cartridge having a groove narrower than the groove  52 , the cartridge abuts the base  62   b , preventing the cartridge from being inserted any further. This construction effectively prevents the user from loading an inappropriate cartridge, protecting the user from poor print quality due to inadvertent use of inappropriate cartridge. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.