BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross section of an image forming apparatus according to an embodiment of the present invention is applied;
FIG. 2 is a schematic cross section of a photosensitive drum and a configuration to support the photosensitive drum according to a first comparative example;
FIG. 3 is a schematic perspective view of a frame of an image forming apparatus, process cartridges, and a positioning holding member according to the first comparative example;
FIG. 4 is a front view of the positioning holding member that is in a closed position and a sliding member placed in a first position according to the first comparative example;
FIG. 5 is a front view of the positioning holding member that is in the closed position and the sliding member placed in a second position according to the first comparative example;
FIG. 6 is an exploded perspective view of the sliding member, the positioning holding member, and the process cartridges according to the first comparative example;
FIG. 7 is a perspective view of the positioning holding member and the sliding member viewed from the inside of the image forming apparatus according to the first comparative example;
FIG. 8 is a schematic perspective view of a frame of an image forming apparatus, process cartridges, and a positioning holding member according to a second comparative example;
FIG. 9 is a front view of the surroundings of an attachment hole in the positioning holding member of a positioning unit according to the second comparative example;
FIG. 10 is a front view of the positioning holding member that is in a closed position and a sliding member placed in a first position according to the second comparative example;
FIG. 11 is a front view of the positioning holding member that is in the closed position and the sliding member placed in a second position according to the second comparative example;
FIG. 12 is an exploded perspective view for explaining how a pressing member is attached to the positioning holding member according to the second comparative example;
FIG. 13 is an exploded perspective view for explaining how a spring is attached to the positioning holding member with the pressing member according to the second comparative example;
FIG. 14 is a plan cross section of a relevant part for explaining the relationship between a bending angle of cut-and-bent members on the sliding member and the attachment of the spring;
FIG. 15 is a schematic for explaining the shape of the spring in detail;
FIG. 16 is a perspective view of a relevant part after the spring is attached to the positioning holding member with the pressing member according to the second comparative example;
FIG. 17 is an exploded perspective view of the surroundings of the positioning holding member, the sliding member, and a cover of the positioning unit according to the second comparative example;
FIG. 18 is a schematic for explaining a movement of an operation lever;
FIG. 19 is a perspective view of a relevant part of an image forming apparatus with a front cover open to expose the positioning unit and pressing position indicators according to a first embodiment of the present invention;
FIG. 20 is an exploded perspective view of a relevant part for explaining the positional relationship between the operation lever and positioning holes and positioning pins on the positioning holding member, and also explaining a pressing position indicating portion according to a modification of the first embodiment;
FIG. 21 is an exploded perspective view of a relevant part for explaining the positional relationship between an operation lever and the positioning holes and the positioning pins on the positioning holding member, and also explaining the pressing position indicating portion, according to another modification than the one shown in FIG. 20;
FIG. 22 is a front view for explaining an open state obtained by using operation levers and the positional relationship of the positioning holes in the positioning holding member, according to yet another modification than the ones shown in FIGS. 20 and 21;
FIG. 23 is a front view for explaining a fixed state obtained by using the operation levers shown in FIG. 22;
FIG. 24 is a perspective view for explaining how the operation lever and regulating members are arranged on the cover according to a second embodiment of the present invention;
FIG. 25 is a perspective view for explaining how the operation lever and regulating members are arranged on the cover according to a modification of the second embodiment;
FIG. 26 is a perspective view for explaining how the operation lever and regulating members are arranged on the cover according to another modification than the one shown in FIG. 25;
FIG. 27 is a perspective view in which the operation lever in the modification shown in FIG. 26 is not shown;
FIG. 28 is a perspective view for explaining how the operation lever and a regulating member are arranged on the cover according to yet another modification than the ones shown in FIGS. 25 and 26 in which the operation lever is not shown;
FIG. 29A is a perspective view for explaining how the operation lever and regulating members are arranged on the cover according to yet another modification than the ones shown in FIGS. 25 to 28 in which the operation lever is not shown;
FIG. 29B is a perspective view for explaining the width of the operation lever;
FIG. 30 is a schematic for explaining a movement of the operation lever that is more similar to the one according to the embodiment than the one shown in FIG. 18;
FIG. 31 is a perspective view for explaining how the operation lever that is more similar to the one according to the embodiment than that shown in FIGS. 17 and 18 is arranged on the cover;
FIG. 32 is a perspective view for explaining how the operation lever that is more similar to the one according to the embodiment than that shown in FIG. 25 is arranged on the cover;
FIG. 33 is a perspective view of a relevant part of a fixing unit for an operation lever according to a third embodiment of the present invention;
FIG. 34 is a perspective view of a relevant part of an independent fixing unit for the operation lever according to a modification of the third embodiment;
FIG. 35 is a perspective view of a relevant part of an independent fixing unit for the operation lever according to another modification than the one shown in FIG. 34;
FIG. 36 is a perspective view of a relevant part including the operation lever, the fixing unit, and a detecting unit according to yet another modification than the ones shown in FIGS. 34 and 35; and
FIG. 37 is an exploded perspective view for explaining a modification in which the entire positioning unit is restrained.