Abstract:
A developing blade apparatus may include a supporting a protrusion and a developing blade connected to the supporting member and including an opening. The protrusion of the supporting member may be disposed within the opening. The developing blade may include a plurality of weld marks that includes a first weld mark and a second weld mark. The protrusion and the opening are disposed between the first weld mark and the second weld mark on an imaginary straight line connecting the first weld mark and the second weld mark.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Japanese Patent Application No. 2013-205678, filed on Sep. 30, 2013, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    Aspects disclosed herein relate to a blade assembly in which a blade is joined to a supporting member by welding, a developing device using the blade assembly, and a manufacturing method of the developing device. 
       BACKGROUND 
       [0003]    Conventionally, there has been an electrophotographic image forming apparatus that includes a developing device including a developing roller and a blade assembly for regulating a thickness of a developer layer held on the developing roller. Further, there has been known a blade assembly that includes a blade that contacts the developing roller and a supporting member that holds the blade in an overlapping manner. 
         [0004]    The blade has a pair of openings and the supporting member includes a pair of positioning protrusions. The openings are engaged with the positioning protrusions, respectively, thereby determining a position of the blade with respect to the supporting member in the blade assembly. The blade is welded to the supporting member at a portion of the blade between the positioning protrusions along the blade in an extended dimension of the blade. 
       SUMMARY 
       [0005]    In the known blade assembly, as described above, the blade may be welded to the supporting member at the portion of the blade between the positioning protrusions only. In some cases, therefore, one or more portions of the blade around one or both of the openings may come off from the supporting member. When such a case happens, a contact pressure between the blade and the developing roller may vary greatly, thereby causing degradation in print quality. 
         [0000]    Accordingly, for example, aspects of the disclosure provide for a developing device, a blade assembly, and a developing device manufacturing method in which a blade may be securely fixed to a supporting member to improve print quality. 
         [0006]    According to the aspects of the disclosure, a developing blade apparatus may include a supporting a protrusion and a developing blade connected to the supporting member and including an opening. The protrusion of the supporting member may be disposed within the opening. The developing blade may include a plurality of weld marks that includes a first weld mark and a second weld mark. The protrusion and the opening are disposed between the first weld mark and the second weld mark on an imaginary straight line connecting the first weld mark and the second weld mark. 
         [0007]    According to the aspects of the disclosure, the blade may be welded to the supporting member at the plurality of locations in the vicinity of the positioning protrusion, thereby preventing or reducing coming off of the blade from the supporting member in the vicinity of the positioning protrusion. This configuration may therefore prevent or reduce an occurrence of variations in contact pressure between the blade and the developing roller, thereby improving print quality. 
         [0008]    This summary is not intended to identify critical or essential features of the disclosure, but instead merely summarizes certain features and variations thereof. Other objects, features, and advantages will be apparent to persons of ordinary skill in the art from the following detailed description of the disclosure and the accompanying drawings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0009]    Aspects of the disclosure are illustrated by way of example and not by limitation in the accompanying figures in which like reference characters indicate similar elements. 
           [0010]      FIG. 1  is a disassembled perspective view depicting a developing device in an illustrative embodiment according to one or more aspects of the disclosure. 
           [0011]      FIG. 2  is a sectional view depicting the developing device in the illustrative embodiment according to one or more aspects of the disclosure. 
           [0012]      FIG. 3A  illustrates a blade unit according to one or more aspects of the disclosure. 
           [0013]      FIG. 3B  is an enlarged view of a first weld mark and a second weld mark formed in the vicinity of a circular opening according to one or more aspects of the disclosure. 
           [0014]      FIG. 3C  is an enlarged view of a first weld mark and a second weld mark formed in the vicinity of an elongated opening according to one or more aspects of the disclosure. 
           [0015]      FIG. 4A  is a diagram for explaining a positioning process in a developing device manufacturing method according to one or more aspects of the disclosure. 
           [0016]      FIG. 4B  is a diagram for explaining a welding process in the developing device manufacturing method according to one or more aspects of the disclosure. 
           [0017]      FIG. 5A  illustrates a blade unit in a first variation according to one or more aspects of the disclosure. 
           [0018]      FIG. 5B  is an enlarged view of a third weld mark and fourth weld marks formed in the vicinity of the circular opening in the first variation according to one or more aspects of the disclosure. 
           [0019]      FIG. 6  is an enlarged view of a first weld mark and a second weld mark formed in the vicinity of the elongated opening in a second variation according to one or more aspects of the disclosure. 
           [0020]      FIG. 7  is an enlarged view of a fifth weld mark formed at and in the vicinity of the circular opening according to one or more aspects of the disclosure. 
           [0021]      FIG. 8  illustrates a blade unit in a fourth variation according to one or more aspects of the disclosure. 
           [0022]      FIG. 9  illustrates a blade unit in a fifth variation according to one or more aspects of the disclosure. 
           [0023]      FIG. 10  is a perspective view depicting a blade unit in a sixth variation according to one or more aspects of the disclosure. 
           [0024]      FIG. 11  is a sectional view depicting a developing device in a seventh variation according to one or more aspects of the disclosure. 
           [0025]      FIG. 12  is a disassembled perspective view depicting a blade unit in an eighth variation according to one or more aspects of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    For a more complete understanding of the present disclosure, needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following descriptions taken in connection with the accompanying drawings. Hereinafter, illustrative embodiments of the disclosure will be described in detail with reference to the accompanying drawings. 
         [0027]    As depicted in  FIG. 1 , a developing device  1  may comprise a developing roller  2  (an example of a developer carrier), a supply roller  3 , a blade unit (or blade assembly)  4 , and a developing case  5  that may hold these components. 
         [0028]    The developing case  5  may be a container having therein a toner storage chamber  53  capable of storing toner therein. The developing case  5  may also be formed to define an opening  51  in one of its surfaces. The developing case  5  may define an edge of the opening  51  and comprise a blade support surface  52  to which the blade unit  4  may be fixed. 
         [0029]    As depicted in  FIG. 2 , a conveyor member  7  for conveying toner toward the supply roller  3  may be disposed in the toner storage chamber  53 . The conveyor member  7  may comprise a shaft portion  71  that may be rotatably supported by the developing case  5 , and a film  72  (or other agitator) that may rotate along with rotation of the shaft portion  71 . 
         [0030]    As depicted in  FIG. 1 , the developing roller  2  may comprise a cylindrical roller body  2 A and a shaft  2 B that may be inserted into the roller body  2 A and may rotatably interface with the roller body  2 A. The roller body  2 A may have elasticity and may be capable of holding toner on its cylindrical surface. The developing roller  2  may be disposed to close or partially close the opening  51  of the developing case  5 . The shaft  2 B may protrude from the roller body  2 A in an axial direction of the developing roller  2  and may be rotatably supported by the developing case  5 . 
         [0031]    The supply roller  3  may be disposed inside the developing case  5  in contact with the developing roller  2 , and may be rotatably supported by the developing case  5 . The supply roller  3  may be configured to supply toner stored in the developing case  5  to the developing roller  2  as the developing roller  2  rotates. 
         [0032]    The blade unit  4  may comprise a blade  41  and a supporting member  42 . The blade  41  may be disposed near the developing roller  2  such that a tip of the blade  41  may be placed on the developing roller  2 . The supporting member  42  may hold the blade  41 . 
         [0033]    The blade  41  may comprise sheet metal having an approximately rectangular shape (e.g., sheet metal having two longer sides and two shorter sides). The blade  41  may be positioned so that a longer side of the blade extends in a direction that an axis of the developing roller  2  may extend (hereinafter, this direction may be referred to as the longer direction LD (see  FIG. 3A )). That is, a longer side of the blade  41  may be approximately parallel to the axial direction of the developing roller  2 , and a shorter side of the blade  41  may be approximately perpendicular to the axial direction of the developing roller  2  (hereinafter, this approximately perpendicular direction may be referred to as the shorter direction SD (see  FIG. 3A )). The blade  41  may be made of metallic material, for example, stainless steel. In other embodiments, for example, the blade  41  may comprise a sheet metal whose surface may have a coating including press oil. 
         [0034]    For example, the blade  41  may have a thickness of 0.05 to 2.5 mm, a thickness of 0.05 to 0.12 mm, a thickness of 0.05 to 1.00 mm, a thickness of 0.07 to 0.15 mm, or a thickness of 0.08 to 0.12 mm. A longer dimension (e.g., a length) of the blade  41  (extending in the longer direction) may be greater than a dimension of the roller body  2 A of the developing roller  2  in the axial direction. For example, the blade  41  may have a length of 218 to 270 mm, a length of 220 to 260 mm, or a length of 222 to 250 mm. 
         [0035]    The blade  41  may comprise a contact portion  411 , which may protrude toward the developing roller  2  and directly contact the roller body  2 A of the developing roller  2 . The contact portion  411  may protrude from a distal end  41 E of a lower surface  41 F (e.g., a surface facing the developing roller  2 ) of the blade  41  (see  FIG. 2 ). The contact portion  411  may be made of, for example, rubber and may extend in the longer direction of the blade  41 . 
         [0036]    The supporting member  42  may be a member for fixing or otherwise holding a fixed end of the blade  41  to the developing case  5 . 
         [0037]    The supporting member  42  may be made of metallic material, for example, electrolytic zinc-coated carbon steel sheet. The supporting member  42  may have a thickness greater than the blade  41  and an approximately or substantially rectangular shape. A longer side of the supporting member  42  may be positioned so that it extends in a direction that is approximately parallel to the longer side of the blade  41 . The supporting member  42  may extend so as to exceed both ends  413  of the blade  41 . That is, the longer side of the supporting member  42  may be longer than the longer side of the blade  41 . 
         [0038]    The ends of the supporting member  42  may extend past the ends  413  of the blade  41 . The supporting member  42  may extend over the blade  41  on a side opposite to the blade support surface  52  so that the supporting member  42  may pinch the blade  41  in conjunction with the blade support surface  52  of the developing case  5 . In other words, the supporting member  42  and blade support surface  52  may be positioned such that the blade  41  is interposed therebetween. The blade  41  may be pinched between an edge  42 E of the supporting member  42  and an edge  52 E of the support surface  52 . A portion, which may contact the edge  42 E of the supporting member  42  and the edge  52 E of the blade support surface  52 , of the blade  41  may function as a fulcrum when the blade  41  bends. 
         [0039]    The blade unit  4  configured as described above may be fixed to the developing case  5  using screws  6  through holes H in the blade  41  and the supporting member  42 . In this state, the blade unit  4  may be configured to regulate a thickness of a toner layer attaching to the developing roller  2 . In particular, the contact portion  411  of the blade  41 , which may contact the rotating developing roller  2 , may regulate a thickness of the toner layer by blocking excess toner from passing as the developing roller  2  rotates. 
         [0040]    As depicted in  FIG. 3A , the supporting member  42  may comprise a positioning protrusion  421 , which may be engaged with the blade  41 , e.g., at opposite end portions of the longer side of the blade  41 . The positioning protrusion  421  may protrude from a surface of the supporting member  42  that faces the blade  41 . As shown in the example embodiment of  FIG. 3A , the blade  41  may have a pair of openings  412  that may be engaged with a pair of positioning protrusions  421 . One of the pair of openings  412  may be a circular opening  412 R and the other of the pair of openings  412  may be an elongated opening  412 L. The elongated opening  412 L of the pair of openings  412  may absorb a dimensional deviation between the two openings  412  and linear expansion of the blade  41  and/or the supporting member  42  in the longer direction that may occur during welding. In other words, for example, the elongated opening  412 L may be elongated in order for the blade  41  to stay engaged with one of the positioning protrusions  421  if the blade  41  expands as a result of welding. 
         [0041]    As depicted in  FIG. 3B , the circular opening  412 R may have substantially the same size as the corresponding positioning protrusion  421 . As depicted in  FIG. 3C , the elongated opening  412 L may comprise a pair of first edges  412 A and a pair of second edges  412 B. The first edges  412 A may be spaced apart from each other at an interval that may be substantially equal to the diameter of the corresponding positioning protrusion  421  and may be positioned on opposite sides of the corresponding positioning protrusion  421  in the shorter direction of the blade  41 . The second edges  412 B may be spaced apart from each other at an interval that may be greater than the diameter of the corresponding positioning protrusion  421  and may be positioned on opposite sides of the corresponding positioning protrusion  421  in the longer direction of the blade  41 . 
         [0042]    As depicted in  FIG. 3A , the blade  41  may be positioned with respect to the supporting member  42  by the engagement of the openings  412  and the corresponding positioning protrusions  421 , respectively. 
         [0043]    The blade  41  may be welded to the supporting member  42  at a plurality of locations along the blade  41  in the longer direction. More specifically, the blade  41  may be joined to the supporting member  42  by laser welding at multiple portions of the blade  41 , including portions of the blade  41  between the positioning protrusions  421  and the ends  413  of the blade  41  and portions of the blade  41  between the positioning protrusions  421  themselves. 
         [0044]    The blade  41  may have a first weld mark  43 , which may join the blade  41  and the supporting member  42  at a position between the positioning protrusions  421 , and second weld marks  44 , which may join the blade  41  and the supporting member  42  at respective positions located towards an outer edge of the supporting member  42  from the respective positioning protrusions  421  in the longer direction. 
         [0045]    The first weld mark  43  may extend from a vicinity of one of the openings  412  to a vicinity of the other of the openings  412  along the longer dimension of the blade  41 . Edges of the first weld mark  43  may be, for example, 0.1 to 5.0 mm apart from the edge of the circular opening  412 R and the edge of the elongated opening  412 L, respectively. In other embodiments, for example, the edges of the first weld mark  43  may be 0.1 to 4.0 mm, 0.5 to 3.0 mm, or 0.7 to 2.0 mm apart from the edge of the circular opening  412 R and the edge of the elongated opening  412 L, respectively. 
         [0046]    As depicted in  FIG. 3A , the second weld marks  44  may extend from respective vicinities of the openings  412  to respective vicinities of the ends  413  of the blade  41  along the longer direction of the blade  41 . Edges of each second weld mark  44  may be, for example, 0.1 to 5.0 mm apart from the edge of the circular opening  412 R and the edge of the elongated opening  412 L, respectively. In other embodiments, for example, the edges of each second weld mark  44  may be 0.1 to 4.0 mm, 0.5 to 3.0 mm, or 0.7 to 2.0 mm apart from the edge of the circular opening  412 R and the edge of the elongated opening  412 L, respectively. 
         [0047]    As depicted in  FIG. 3B , an edge, which may be located close to the circular opening  412 R, of the first weld mark  43  and an edge, which may be located close to the circular opening  412 R, of the second weld mark  44  may be located on opposite sides of the positioning protrusion  421 , which may be engaged with the circular opening  412 R, in the direction that the contact portion  111  may extend, that is, in the longer direction of the blade  41 . 
         [0048]    The first weld mark  43  may comprise a proximity point P 1  that may be closest to the positioning protrusion  421 , with which the circular opening  412 R may be engaged, in the vicinity of the positioning protrusion  421 . The second weld mark  44  may comprise a proximity point P 2  that may be closest to the positioning protrusion  421 , with which the circular opening  412 R may be engaged, in the vicinity of the positioning protrusion  421 . A line segment L 1  intersecting the proximity point P 1  and the proximity point P 2  may pass the positioning protrusion  421 . 
         [0049]    As depicted in  FIG. 3C , an edge, which may be located close to the elongated opening  412 L, of the first weld mark  43  and an edge, which may be located close to the elongated opening  412 L, of the second weld mark  44  may be located on opposite sides of the positioning protrusion  421 , which may be engaged with the elongated opening  412 L, in the longer direction of the blade  41 . 
         [0050]    The first weld mark  4  may comprise a proximity point P 3  that may be closest to the positioning protrusion  421 , with which the elongated opening  412 L may be engaged, in the vicinity of the positioning protrusion  421 . The second weld mark  44  may comprise a proximity point P 4  that may be closest to the positioning protrusion  421 , with which the elongated opening  412 L may be engaged, in the vicinity of the positioning protrusion  421 . A line segment L 2  intersecting the proximity point P 3  and the proximity point P 4  may pass the positioning protrusion  421 . 
         [0051]    Hereinafter, advantages of the blade unit  4 , configured in accordance with this disclosure, are described. 
         [0052]    The blade  41  may be welded to the supporting member  42  at a plurality of, for example, two, locations on opposite sides of each positioning protrusion  421  in the vicinity of each positioning protrusion  421 , thereby preventing or reducing coming off of the blade  41  from the supporting member  42 . Therefore, variations in contact pressure between the blade  41  and the developing roller  2  may be reduced, thereby improving print quality. 
         [0053]    Next, a manufacturing method of the developing device  1  is described. 
         [0054]    When the blade unit  4  is assembled, as depicted in  FIG. 4A , the blade  41  may first be placed on the supporting member  42 . At that time, the openings  412  in the blade  41  may be engaged with the corresponding positioning protrusions  421  of the supporting member  42  (e.g., a positioning process). 
         [0055]    Then, the blade  41  and the supporting member  42  may be fastened on a worktable. Thereafter, as depicted in  FIG. 4B , while a laser beam  81  irradiated from the welding machine  8  is moved with respect to the blade  41 , the laser beam  81  may be irradiated onto the blade  41  to weld the blade  41  and the supporting member  42  to each other (e.g., a welding process). 
         [0056]    In some embodiments, the welding machine  8  may be configured to irradiate a portion, which may face the welding machine  8 , of an object with a continuous wave laser or a pulsed laser. That is, the laser beam  81  may be a continuous wave laser or a pulsed laser. In other embodiments, for example, another welding machine that may be configured to irradiate the blade  41  with a laser beam by moving a reflector provided inside the welding machine, without moving the welding machine itself, may be used. For example, a fiber laser may be used as the continuous wave laser, and an yttrium aluminum garnet (“YAG”) laser or a fiber laser may be used as the pulsed laser. In particular, a fiber laser (which emits a laser beam with a relatively small diameter) may be used so that the welding process for creating overlapping weld marks does not cause overheating and/or deformation of the blade  41  and/or the supporting member  42 . 
         [0057]    In the welding process, the laser beam  81  may be moved with respect to the blade  41  along the longer direction of the blade  41  from one end portion, in which the circular opening  412 R may be defined, to the other end portion, in which the elongated opening  412 L may be defined. In particular, the laser beam  81  may be moved on a straight line passing through the positioning protrusions  42  along the longer direction of the blade  41 . That is, a portion of the blade  41  between the end portion, which may be located closer to the circular opening  412 R, of the blade  41  and the vicinity of the circular opening  412 R may be welded first to form a second weld mark  44 . Then, a portion of the blade  41  between the circular opening  412 R and the elongated opening  412 L may be welded to form a first weld mark  43 . Thereafter, a portion of the blade  41  between the vicinity of the elongated opening  412 L and the end portion, which may be located closer to the elongated opening  412 L, of the blade  41  may be welded to form another second weld mark  44 . 
         [0058]    Then, the laser beam  81  may be irradiated onto portions between the ends  413  of the blade  41  and the edges of the openings  412 , without contacting the ends  413  of the blade  41  and the edges of the openings  412 . 
         [0059]    Using the manufacturing method according to the disclosure, the blade  41  may be welded to the supporting member  42  at the plurality of, for example, two, locations on opposite sides of each positioning protrusion  421  in the vicinity of each positioning protrusion  421 . 
         [0060]    Starting the welding from the vicinity of the circular opening  412 R and ending at the vicinity of the elongated opening  412 L as described above may allow the elongated opening  412  to absorb a thermal expansion of the blade  41  that may occur during welding. 
         [0061]    While the disclosure has been described in detail with reference to example embodiments thereof, it is not limited to such examples. Various changes, arrangements and modifications may be applied to the detailed configuration without departing from the spirit and scope of the disclosure. In the description below, common parts have the same reference numerals as those of the above-described embodiments, and the detailed description of the common parts is omitted. 
         [0062]    As described above, the blade  41  may be welded to the supporting member  42  at the plurality of, for example, two, locations on opposite sides of each positioning protrusion  421  in the vicinity of each positioning protrusion  421 . However, the number of locations where the blade  41  and the supporting member  42  may be welded to each other might not be limited to that example. In other embodiments, for example, as depicted in  FIG. 5A , the blade  41  and the supporting member  42  may be welded to each other at, for example, three locations in the vicinity of each positioning protrusion  421 . 
         [0063]    More specifically, a third weld mark  45  and two fourth weld marks  46  may be formed in the vicinity of each positioning protrusion  421  on the blade  41 . 
         [0064]    Third weld marks  45  may be formed at a plurality of locations between the positioning protrusions  421  in the longer direction of the blade  41 . Of the third weld marks  45 , third weld marks  45  that may be formed at respective positions closest to the positioning protrusions  421 , respectively, may be positioned such that their edges, which may be located close to the respective positioning protrusions  421 , are located near the respective edges of the openings  412 . 
         [0065]    The fourth weld marks  46  may have a circular shape. The fourth weld marks  46  may be formed at two respective locations located towards the outer edges of the blade  41  from the respective positioning protrusions  421  in the longer direction of the blade  41 . The fourth weld marks  46  may be spaced apart from each other in the shorter direction of the blade  41  while the fourth weld marks  46  are located on opposite sides of each positioning protrusion  421 . 
         [0066]    As depicted in  FIG. 5B , the third weld mark  45  may comprise a proximity point P 5  that may be closest to the positioning protrusion  421  with which the circular opening  412 R may be engaged. Each fourth weld mark  46  may comprise a proximity point P 6  that may be closest to the positioning protrusion  421  with which the circular opening  412 R may be engaged. A line segment L 3  extending between the proximity point P 5  and one of the proximity points P 6 , another line segment L 3  extending between the proximity point P 5  and the other of the proximity points P 6 , and a line segment L 4  extending between the proximity points P 6  may enclose the positioning protrusion  421 . 
         [0067]    As described above, the first weld mark  43  and the second weld mark  44  may be formed without contacting the edges of the openings  412 . However, the locations where the weld marks may be formed might not be limited to that example. In other embodiments, for example, as depicted in  FIG. 6 , the first weld mark  43  and the second weld mark  44  formed around the elongated opening  412 L may contact the edges (e.g., the second edges  412 B) of the elongated opening  412 L or extend to the elongated opening  412 L beyond the edges (e.g., the second edges  412 B) of the elongated opening  412 L. 
         [0068]    In other embodiments, for example, as depicted in  FIG. 7 , one or more portions of the edge of the circular opening  412 R and the corresponding positioning protrusion  421  may be welded to each other. The blade  41  may thus have a weld mark  47  that may join the positioning protrusion  421  and the one or more portions of the edge of the circular opening  412 R in the blade  41  to each other. 
         [0069]    As described above, the openings  412  may comprise the circular opening  412 R and the elongated opening  412 L. However, the shapes of the pair of openings might not be limited to that example. In other embodiments, for example, as depicted in  FIG. 8 , a pair of openings  414  may comprise cutouts that may be defined in both the ends of the blade  41  in the longer direction of the blade  41  and may be recessed inward in the longer direction of the blade  41 . 
         [0070]    In this case, the blade  41  and the supporting member  42  may be welded to each other at two locations on opposite sides of each positioning protrusion  421  in the vicinity of each positioning protrusion  421  in a direction perpendicular to the longer direction of the blade  41 . Therefore, the blade  41  may have two weld marks  48  formed on opposite sides of each positioning protrusion  421  in the shorter direction of the blade  41 . 
         [0071]    In other embodiments, for example, as depicted in  FIG. 9 , the pair of openings  412  may comprise elongated openings only. 
         [0072]    In this case, when the blade  41  and the supporting member  42  are fastened on a worktable prior to the welding process, the position of the blade  41  may be determined with respect to the supporting member  42  using a jig. In the welding process, a first weld mark  43  may be formed between the openings  412  and second weld marks  49  may be formed at respective locations towards the outer edges of the blade  41  from the respective positioning protrusions  421  in the longer direction of the blade  41 . 
         [0073]    As described above, in the welding process, the laser beam  81  may be moved with respect to the blade  41 . However, the manner of moving the laser beam  81  with respect to the blade  41  might not be limited to that example. In other embodiments, for example, the blade  41  and the supporting member  42  may be moved with respect to the laser beam  81  and the laser beam  81  may be stationary. 
         [0074]    In still other embodiments, the laser beam  81  and the set of the blade  41  and the supporting member  42  may be moved at the same time. 
         [0075]    As described above, the contact portion  411  may be formed on the blade  41  to protrude from the blade  41 . However, the configuration of the blade  41  might not be limited to that example. In other embodiments, for example, as depicted in  FIG. 10 , the blade  41 A might not comprise a contact portion made of, for example, rubber, but may comprise a bent portion  411 A in which the distal end portion of the blade  41 A may be bent toward the supporting member  42  (e.g., toward a side opposite to the developing roller  2 ). The bent portion  411 A (e.g., the distal end of the blade  41 ) may directly contact the roller body  2 A of the developing roller  2 . 
         [0076]    As described above, the distal end portion of the blade  41  may be placed on the developing roller  2 , and the blade  41  may be pinched by the supporting member  42  and the developing case  5 . However, the configuration of the blade unit  4  might not be limited to that example. In other embodiments, for example, as depicted in  FIG. 12 , the supporting member  42  to which the blade  41  may be welded may be fixed to the developing case  5  directly while the supporting member  42  is pinched by the blade  41  and the developing case  5 . In the blade unit  4 , the distal end portion of the blade  41  (e.g., the contact portion  411 ) may contact the developing roller  2  from the conveyor member  7  side, and the surface, which may be opposite to the surface  41 F having the contact portion  411  thereon, of the blade  41  may be supported by the supporting member  42 . 
         [0077]    As described above, the developing roller  2  comprising the roller body  2 A and the shaft  2 B are illustrated as the developer carrier. However, in other embodiments, the developer carrier might not be limited to that example. In other embodiments, for example, a brush roller, a developing sleeve, or a belt-shaped developer carrier may be adopted as the developer carrier. 
         [0078]    As described above, the contact portion  411  (e.g., the distal end) of the blade  41  may be in direct contact with the roller body  2 A of the developing roller  2  (as an example of the developer carrier). However, the configuration of the blade might not be limited to that example. In other embodiments, for example, the blade may be disposed such that its distal end portion may be substantially 0.1 to 1.0 mm apart from the roller body  2 A. 
         [0079]    As described above, the supporting member  42  may comprise the positioning protrusions  421  and the blade  41  may have the openings  412  that may engage with the respective positioning protrusions  421 . However, the configuration of the blade unit  4  might not be limited to that example. In other embodiments, for example, as depicted in  FIG. 12 , the blade  41  may comprise positioning protrusions  415  that may protrude toward the supporting member  42  from respective end portions of the blade  41  in the longer direction of the blade  41 . The supporting member  42  may have therein openings  422  that may be defined at respective positions corresponding to the respective positioning protrusions  415 . 
         [0080]    As described above, stainless steel may be used as the metallic material for the blade  41 . However, the material of the blade  41  might not be limited to that example. For example, the blade  41  may be made of, for example, steel used for springs, phosphor bronze, beryllium copper, or carbon tool steel. In a case where the steel used for springs or the carbon tool steel is used, a nickel, chromium, or zinc coating may be applied to the blade  41  to prevent or reduce rust. 
         [0081]    As described above, the electrolytic zinc-coated carbon steel sheet may be used as the metallic material for the supporting member  42 . However, the configuration of the supporting member  42  might not be limited to that example. In other embodiments, for example, the supporting member  42  may be made of a cold rolled steel plate or a tin plate, or a plate made of one of the cold rolled steel plate and the tin plate whose surface may be applied with treatment such as Parkerizing, chromating, or nickel coating. The supporting member  42  may also have a coating including press oil thereon.