Abstract:
A method for welding a developing blade to a supporting member may include increasing a relative movement speed of a welding laser and a developing blade, along a moving direction. The method may include maintaining, upon the welding laser reaching the developing blade, the relative movement speed and initiating irradiation of the welding laser toward the developing blade and the supporting member.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Japanese Patent Application No. 2013-205679, 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]    In the blade assembly, the blade and the supporting member are welded to each other at a plurality of locations along the blade in an extended dimension of the blade. Therefore, the blade is formed with a plurality of weld marks that are aligned in the extended dimension of the blade. 
       SUMMARY 
       [0005]    In some cases, to weld the blade and the supporting member to each other as described above, for example, a laser beam is irradiated onto the blade while the laser beam is moved with respect to the blade in the extended dimension of the blade. While the laser beam is moved, a moving speed of the laser beam at the start of and at the end of the movement may become slower than the moving speed of the laser beam during the period other than the start of and the end of the movement. Thus, weld marks formed on the blade at the start of and at the end of the movement may be larger in size than the other weld marks formed during the period other than the start of and the end of the movement. 
         [0006]    Variations in size of the weld marks occurring depending on the locations may cause large variations in pressure contact between the blade and the developing roller. 
         [0007]    Accordingly, for example, aspects of the disclosure provide for a developing device, a blade assembly, and a developing device manufacturing method in which quality of the blade assembly may be improved. According to the aspects of the disclosure, a method for welding a developing blade to a supporting member may include increasing a relative movement speed of a welding laser and a developing blade, along a moving direction. The method may include maintaining, upon the welding laser reaching the developing blade, the relative movement speed and initiating irradiation of the welding laser toward the developing blade and the supporting member. 
         [0008]    According to the other aspects of the disclosure, a method for welding a developing blade to a supporting member, may include forming, by a welding laser of a welding apparatus, a first weld mark at a first position on the developing blade to connect the developing blade to the supporting member, wherein the first weld mark is an initial weld mark from an edge of the developing blade in a movement direction of the welding laser, and wherein the first weld mark is formed with a first width in a direction perpendicular to the movement direction of the welding laser; and forming a second weld mark at a second position of the developing blade to connect the developing blade to the supporting member, wherein the second position is a central position along the developing blade in the movement direction of the welding laser, and wherein the second weld mark is formed with a second width in the direction perpendicular to the movement direction of the welding laser, wherein the first width is between 0.8 and 1.2, inclusive, times as large as the second width. 
         [0009]    According to the aspects of the disclosure, the weld marks formed on the blade or on the blade and the supporting member may have substantially the same size, thereby improving the quality of the blade assembly. 
         [0010]    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 
         [0011]    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. 
           [0012]      FIG. 1  is a disassembled perspective view depicting a developing device in an illustrative embodiment according to one or more aspects of the disclosure. 
           [0013]      FIG. 2  is a sectional view depicting the developing device in the illustrative embodiment according to one or more aspects of the disclosure. 
           [0014]      FIG. 3A  illustrates a blade unit according to one or more aspects of the disclosure. 
           [0015]      FIG. 3B  is an enlarged view of a portion A of  FIG. 3A  according to one or more aspects of the disclosure. 
           [0016]      FIG. 3C  is an enlarged view of a portion B of  FIG. 3A  according to one or more aspects of the disclosure. 
           [0017]      FIG. 4A  is a diagram for explaining a preparation process in a developing device manufacturing method according to one or more aspects of the disclosure. 
           [0018]      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. 
           [0019]      FIG. 4C  is an enlarged view of a portion onto which a laser beam is irradiated, in the blade, according to one or more aspects of the disclosure. 
           [0020]      FIG. 5A  illustrates a blade unit in a first variation according to one or more aspects of the disclosure. 
           [0021]      FIG. 5B  is an enlarged view of weld marks in the first variation according to one or more aspects of the disclosure. 
           [0022]      FIG. 6  illustrates a blade unit in a second variation according to one or more aspects of the disclosure. 
           [0023]      FIG. 7  illustrates a blade unit in a third variation according to one or more aspects of the disclosure. 
           [0024]      FIG. 8  illustrates a blade unit in a fourth variation according to one or more aspects of the disclosure. 
           [0025]      FIG. 9  illustrates a blade unit in a fifth 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 and the other of the pair of openings  412  may be an elongated opening. The elongated opening 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  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. 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. 
         [0041]    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  at end portions of the blade  41 , 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. 
         [0042]    The blade  41  may have a first combined weld mark  43 , which may join the blade  41  and the supporting member  42  at a position between the positioning protrusions  421 , and second combined 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. 
         [0043]    The first combined 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 . 
         [0044]    As depicted in  FIG. 3B , the first combined weld mark  43  may include a plurality of weld marks  43 A that may be aligned along the longer direction of the blade  41 , wherein adjacent weld marks of the plurality weld marks  43 A may overlap each other. That is, the plurality of weld marks  43 A that the blade  41  may have may partially overlap one another, thereby forming the combined weld mark  43 . A weld mark may refer to a welded portion (e.g., a modified portion of the blade and/or supporting member) that may be formed by one continuous application (e.g., one pulse) of a laser beam. 
         [0045]    Each weld mark  43 A may have a shape and size corresponding to the shape and size (e.g., diameter) of the laser beam used to create the weld mark. The circular shape, as shown in the example of  FIG. 3B , may include a circular shape in which a dimension of a most elongated portion (e.g., longest diameter) may be within a range of 110% to 330% of a dimension of a least elongated portion (e.g. shortest diameter). In other embodiments, for example, the dimension of the most elongated portion (e.g., longest diameter) may be within a range of 110% to 250%, a range of 100% to 120%, a range of 100% to 110%, a range of 101% to 105%, or a range of 101% to 115% of the dimension of the least elongated portion (e.g. shortest diameter). For example, the weld marks  43 A may have a size of 0.1 to 0.4 mm. 
         [0046]    The plurality of weld marks  43 A may overlap on top of one another in an order in which the plurality of weld marks  43 A may be arranged in the longer direction of the blade  41 . For example, when creation of the weld mark  43 A begins from the circular opening  412  side of the blade  41 , a weld marks  43 A formed further from the circular opening  412  may be formed over the adjacent weld mark  43 A formed closer to the circular opening  412  (see dotted lines illustrated in  FIG. 3B ). 
         [0047]    As depicted in  FIG. 3A , the second combined 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 . 
         [0048]    In a similar manner to the first combined weld mark  43  depicted in  FIG. 3C , each second combined weld mark  44  may include a plurality of circular weld marks  44 A that may be arranged along the longer direction of the blade  41 , and that may overlap with one another. 
         [0049]    Of the weld marks  44 A included in the second combined weld mark  44 , the outermost ones of the weld marks  44 A may be formed on the blade  41  along the longer direction of the blade  41  while a gap is left between edges of the outermost weld marks  44 A and the ends  413  of the blade  41 . The gap may be smaller than a nugget diameter D of the weld mark  44 A. 
         [0050]    As depicted in  FIGS. 3B and 3C , the first combined weld mark  43  and the second combined weld marks  44  may have substantially the same dimension (e.g., a width) in the shorter direction of the blade  41 . Comparing a dimension W2 (e.g., a width) in the shorter direction of the blade  41  of the outermost weld marks  44 A included in one of the second combined weld marks  44  in the longer direction of the blade  41  with a dimension W1 (e.g., a width) in the shorter direction of the blade  41  of a middle weld mark  43 A included in the first combined weld mark  43  in the longer direction of the blade  41 , the dimension W2 of the outermost weld mark  44 A of the second combined weld mark  44  may be 0.80 to 1.20 times as large as the dimension W1 of the middle weld mark  43 A of the first combined weld mark  43 . In other embodiments, for example, the dimension W2 of the outermost weld mark  44 A of the second combined weld mark  44  may be 0.90 to 1.01 times, 0.85 to 1.25 times, or 0.90 to 1.1 times as large as the dimension W1 of the middle weld mark  43 A of the first combined weld mark  43 . 
         [0051]    That is, the dimension W2 in the shorter direction of the blade  41  of one of the outermost weld marks of all the weld marks in the weld marks  43 A and  44 A formed on the blade  41  in the longer direction of the blade  41  may be 0.80 to 1.20 times as large as the dimension W1 in the shorter direction of the blade  41  of the middle weld mark of all the weld marks in the weld marks  43 A and  44 A formed on the blade  41  in the longer direction of the blade  41 . In other embodiments, for example, the dimension W2 in the shorter direction of the blade  41  of one of the outermost weld marks of all the weld marks in the weld marks  43 A and  44 A formed on the blade  41  in the longer direction of the blade  41  may be 0.90 to 1.01 times, 0.85 to 1.25 times, or 0.90 to 1.1 times as large as the dimension W1 in the shorter direction of the blade  41  of the middle weld mark of all the weld marks in the weld marks  43 A and  44 A formed on the blade  41  in the longer direction of the blade  41 . 
         [0052]    The weld mark positioned at the middle of all the weld marks in the weld marks  43 A and  44 A formed on the blade  41  in the longer direction of the blade  41  may be determined as the middle weld mark. If there is no weld mark formed on the middle of the line of the weld marks, a weld mark formed at a position closest to the middle of the line of the weld marks in the longer direction of the blade  41  may be determined as the middle weld mark. 
         [0053]    Hereinafter, advantages of the blade unit  4 , configured in accordance with this disclosure, are described. 
         [0054]    The weld marks  43 A of the first combined weld mark  43  and the weld marks  44 A of the second combined weld mark  44  formed on the blade have substantially the same size, thereby reducing or preventing an occurrence of variations in contact pressure between the blade  41  and the developing roller  2  when the blade  41  contacts the developing roller  2 . Therefore, the quality of the blade unit  4  may be improved. 
         [0055]    The blade  41  may be welded to the supporting member  42  while the slight gap that is smaller than the nugget diameter D is left between the edges of the outermost weld marks and the ends  413  of the blade  41  in the longer direction of the blade  41 , whereby the blade  41  might not come off from the supporting member  42  easily. 
         [0056]    Next, a manufacturing method of the blade unit  4  is described. 
         [0057]    When the blade unit  4  is assembled, as depicted in  FIG. 4A , the blade  41  may first be placed on the supporting member  42  (e.g., a preparation process). At that time, the openings  412  in the blade  41  may be engaged with the corresponding positioning protrusions  421  of the supporting member  42 . 
         [0058]    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). 
         [0059]    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 pulsed laser. That is, pulses of the laser beam  81  may be emitted. 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, 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 . 
         [0060]    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  may be defined, to the other end portion, in which the elongated opening  412  may be defined. More specifically, the laser beam  81  may be moved with respect to the blade  41  along the longer direction of the blade  41  from a position more outside than the one end  413  of the blade  41  to a position more outside than the other end  413  of the blade  41 . 
         [0061]    At that time, the welding machine  8  may be moved at a speed which may allow formation of adjacent weld marks  43 A or weld marks  44 A that may overlap each other when the laser beam  81  is irradiated onto the blade  41 . 
         [0062]    The welding machine  8  may be moved first and the laser beam  81  may be then irradiated onto the blade  41 . More specifically, as depicted in  FIG. 4C , the laser beam  81  may be irradiated onto the blade  41  when the center of the laser beam  81  reaches a position a predetermined distance I inside from the one end  413  of the blade  41  while the laser beam  81  is moved from the outside to the inside of the blade  41  with respect to the one end  413  located close to the circular opening  412 . The predetermined distance I may be longer than or equal to a half of the nugget diameter D and shorter than the nugget diameter D. 
         [0063]    While the welding machine  8  is moved, the irradiation of the laser beam  81  may be stopped. Thus, the movement of the welding machine  8  may be stopped after the irradiation of the laser beam  81  is stopped. More specifically, the irradiation of the laser beam  81  may be stopped when the center of the laser beam  81  reaches a position the predetermined distance I inside the other end  413  of the blade  41  while the laser beam  81  is moved from the inside to the outside of the blade  41  with respect to the other end  413  located close to the elongated opening  412 . 
         [0064]    According to the above-described manufacturing method, while the laser beam  81  is irradiated onto the blade  41 , the laser beam  81  moves with respect to the blade  41  at a constant speed. Therefore, the weld marks  43 A and  44 A having substantially the same size may be formed across the blade  41  in the longer direction of the blade  41 . 
         [0065]    Starting the welding from the circular opening  412  side as described above may allow the elongated opening  412  to absorb a thermal expansion of the blade  41  that may occur during welding. 
         [0066]    While the disclosure has been described in detail with reference to the example drawings, it is not limited to such examples. Various changes, arrangements, and modifications may be realized 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. 
         [0067]    As described above, the blade  41  may be welded to the supporting member  42  while the slight gap that is smaller than the nugget diameter D is left between the edges of the outermost weld marks and the ends  413  in the longer direction. However, the configuration of the blade  41  might not be limited to that example. In other embodiments, for example, as depicted in  FIG. 5A , a portion of each end  413  of the blade  41  in the longer direction of the blade  41  may be welded to the supporting member  42 . 
         [0068]    More specifically, the blade  41  may have a plurality of third weld marks  45  between the positioning protrusions  421  along the longer direction of the blade  41  and fourth weld marks  46  at respective positions located towards an outer edge of the supporting member  42  from the respective positioning protrusions  421  in the longer direction. 
         [0069]    As depicted in  FIG. 5B , the weld marks  45  and  46  may be formed on the blade  41  using a continuous wave laser such as a fiber laser and extend along the longer direction of the blade  41 . 
         [0070]    The fourth weld marks  46  may extend from the inside to the outside of the blade  41  beyond the respective ends  413  of the blade  41  in the longer direction of the blade  41 , and may thus be formed on respective portions of the supporting member  42  where there may be no blade  41 . 
         [0071]    The fourth weld mark  46  may have a dimension W4 (e.g., a width) in the shorter direction of the blade  41 . The dimension W4 of the fourth weld mark  46  may be a dimension in the shorter direction of the blade  41  of an outer end portion of an outermost fourth weld mark  46  in the longer direction of the blade  41 . The dimension W4 of the fourth weld mark  46  in the shorter direction of the blade  41  may be 0.8 to 1.2 times as large as a dimension W3 (e.g., a width) of one of the third weld marks  45  in the shorter direction of the blade  41 . 
         [0072]    The blade unit  4  configured as described above may have thereon the weld marks  45  and  46  that may have substantially the same width in the shorter direction of the blade  41 , thereby improving the quality of the blade unit  4  as in the case of the illustrative embodiment. 
         [0073]    The portions of the ends  413  of the blade  41  may be welded to the supporting member  42 . As in the case of the illustrative embodiment, the blade  41  therefore might not come off from the supporting member  42  easily. 
         [0074]    To assemble the blade unit  4  configured as described above, in the welding process, the irradiation of the laser beam  81  may be started before the center of the laser beam  81  reaches the end  413  located close to the circular opening  412  in the blade  41 . The irradiation of the laser beam  81  may be continued until the center of the laser beam  81  passes the end  413  located close to the circular opening  412  in the blade  41 . 
         [0075]    The irradiation of the laser beam  81  may be started before the center of the laser beam  81  reaches the end  413  located close to the elongated opening  412  in the blade  41 . The irradiation of the laser beam  81  may be continued until the center of the laser beam  81  passes the end  413  located close to the elongated opening  412  in the blade  41 . 
         [0076]    As described above, the blade  41  may be welded to the supporting member  42  in the vicinities of the ends  413  in the longer direction of the blade  41 . However, the configuration of the blade unit  4  might not be limited to that example. In other embodiments, for example, as depicted in  FIG. 6 , in a case where the supporting member  42  is shorter in length than the blade in the longer direction of the blade  41 , the second weld marks  47  may be formed inside of respective ends  422  of the supporting member  42  and towards the outer edges of the blade  41  from the respective positioning protrusions  421  in the longer direction of the blade  41 . The supporting member  42  may be welded to the blade  41  while the slight gap that is smaller than the nugget diameter D is left between the second weld marks and the ends  422  of the blade  41  in the longer direction of the blade  41 . 
         [0077]    In still other embodiments, as depicted in  FIG. 7 , the fourth weld marks  48  may be formed over the respective ends  422  of the supporting member  42  in the longer direction of the blade  41  and towards the respective outer edges of the blade  41  from the respective positioning protrusions  421  in the longer direction of the blade  41 . The portions of the ends  422  of the supporting member  42  may be welded to the blade  41  in the longer direction of the blade  41 . 
         [0078]    As described above, the weld marks  43 A may overlap one another to form the combined weld mark  43  on the blade  41  and the weld marks  44 A may overlap one another to form the combined weld mark  44  on the blade  41 . However, the manner of arranging the weld marks might not be limited to that example. In other embodiments, for example, the blade  41  may have circular weld marks that may be spaced apart from each other. 
         [0079]    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. 
         [0080]    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. 
         [0081]    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. 8 , 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 . 
         [0082]    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 . 
         [0083]    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. 
         [0084]    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 0.1-1.0 mm apart from the roller body  2 A. 
         [0085]    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. 
         [0086]    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.