Patent Publication Number: US-7224924-B2

Title: Developing device, image forming apparatus, image forming system, and method of manufacturing developing device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application claims priority upon Japanese Patent Application No. 2004-37141 filed on Feb. 13, 2004, Japanese Patent Application No. 2004-37142 filed on Feb. 13, 2004, and Japanese Patent Application No. 2004-64809 filed on Mar. 8, 2004, which are herein incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to developing devices, image forming apparatuses, image forming systems, and methods of manufacturing developing devices. 
   2. Description of the Related Art 
   (1) There are developing device that are provided with: a developer containing section for containing a developer; a developing roller for bearing the developer contained in the developer containing section; and a roller-supporting member for rotatably supporting the developing roller. 
   In such a developing device, the coefficient of thermal expansion of the developer containing section differs from the coefficient of thermal expansion of the roller-supporting member. Therefore, there is a difference in the amount of expansion/contraction due to a change in temperature between the developer containing section and the roller-supporting member. In view of this, the developing device is provided with a gap for preventing the roller-supporting member and the developer containing section from interfering with one another when the roller-supporting member and the developer containing section expand/contract due to a change in temperature, which is caused by the difference in the coefficient of thermal expansion between the developer containing section and the roller-supporting member. This gap is designed to have a predetermined size, taking into consideration the amount of expansion/contraction of the roller-supporting member and the developer containing section due to a change in temperature. (See, for example, JP 2003-270928A.) 
   However, if the roller-supporting member is formed, for example, by connecting two members, then there are cases in which the roller-supporting member is not formed in the desired size due to variations in size of those members caused by individual differences. If the roller-supporting member is formed larger than the desired size, then the developer containing section and the roller-supporting member may expand/contract and interfere with one another due to a change in temperature. 
   (2) Another type of developing device is provided with: a developing roller for bearing a developer; a roller-supporting member for rotatably supporting the developing roller; and a roller gear that is provided at one end of the developing roller and that is for rotating the developing roller. In such a developing device, an intermediate gear is used for transmitting a drive force from a drive source to the roller gear, and the intermediate gear is supported by a gear-supporting shaft. (See, for example, JP 2003-270928A.) 
   In this type of developing device, the roller-supporting member may be structured by connecting at least two members in order to support the developing roller, and screws are often used to connect these members. 
   In assembling such a roller-supporting member, there has been a demand for improvement in the ease of assembling the roller-supporting member from the standpoint of, for example, shortening the time required for assembly. 
   (3) Further, image forming apparatuses such as laser beam printers are well known in the art. Such image forming apparatuses are provided with, for example, an image bearing body for bearing a latent image, and a developing device that develops the latent image borne on the image bearing body with a developer. When the image forming apparatus receives image signals etc. from an external device such as a host computer, the developing device is positioned in a developing position which is in opposition to the image bearing body, the latent image borne on the image bearing body is developed with the developer contained in the developing device to form a developer image, the developer image is transferred onto a medium, and ultimately an image is formed on the medium. 
   The developing device of the type described above has, for example, a developer charging member for charging the developer borne by a developer bearing roller, a bearing-roller-supporting member that is made of metal and that is for rotatably supporting the developer bearing roller, and a charge-supporting member that is made of metal and that is for supporting the developer charging member. (See, for example, JP 2003-270928A.) 
   In this type of developing device, it is necessary to arrange the developer charging member in an appropriate position with respect to the developer bearing roller so as to electrically charge the developer borne by the developer bearing roller evenly. In order to arrange the developer charging member in an appropriate position with respect to the developer bearing roller, it is necessary to arrange the charge-supporting member, which supports the developer charging member, in a suitable position with respect to the bearing-roller-supporting member, which supports the developer bearing roller. 
   Usually, the bearing-roller-supporting member and the charge-supporting member are fastened to one another with screws. However, if the bearing-roller-supporting member and the charge-supporting member are fastened to one another with screws, then the position of the charge-supporting member with respect to the bearing-roller-supporting member may deviate from its proper position due to the turning force etc. applied to make the screw turn during fastening. In this case, the position of the developer charging member with respect to the developer bearing roller may also deviate. 
   SUMMARY OF THE INVENTION 
   The present invention has been made in light of the foregoing issues. It is an object of the present invention to achieve a developing device, an image forming apparatus, an image forming system, and a method of manufacturing a developing device, with which it is possible to form a roller-supporting member in a desired size with satisfactory precision such that the developer containing section and the roller-supporting member do not interfere with one another even when they expand/contract due to a change in temperature. 
   Another object of the present invention is to achieve a developing device, an image forming apparatus, and an image forming system, with which it is possible to improve the ease in assembling the roller-supporting member. 
   Another object of the present invention is to achieve a developing device, an image forming apparatus and an image forming system provided with such a developing device, and a method of manufacturing the developing device, with which it is possible to arrange the developer charging member in an appropriate position with respect to the developer bearing roller. 
   An aspect of the present invention is a developing device comprising: a developer containing section that is for containing a developer and that has a predetermined coefficient of thermal expansion; a developing roller for bearing the developer contained in the developer containing section; a roller-supporting member that is for rotatably supporting the developing roller, that has a coefficient of thermal expansion which is different from the coefficient of thermal expansion of the developer containing section, and that is structured by connecting at least three members; and a gap for preventing the roller-supporting member and the developer containing section from interfering with one another when the roller-supporting member and the developer containing section expand/contract due to a change in temperature. 
   Another aspect of the present invention is a developing device comprising: a developing roller for bearing a developer; a roller-supporting member that is structured by connecting at least two members and that is for rotatably supporting the developing roller; a roller gear that is provided at one end of the developing roller and that is for rotating the developing roller; an intermediate gear for transmitting a drive force from a drive source to the roller gear; and a gear-supporting shaft for rotatably supporting the intermediate gear, a screw section of the gear-supporting shaft connecting the at least two members that structure the roller-supporting member. 
   Another aspect of the present invention is a developing device comprising: a developer charging member for charging a developer borne by a developer bearing roller; a bearing-roller-supporting member that is made of metal and that is for rotatably supporting the developer bearing roller; and a charge-supporting member that is made of metal and that is for supporting the developer charging member, the charge-supporting member and the bearing-roller-supporting member being welded through spot welding. 
   Other features of the present invention will be made clear through the accompanying drawings and the following description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram showing main structural components constructing a printer  10 ; 
       FIG. 2  is a block diagram showing a control unit of the printer  10 ; 
       FIG. 3  is a perspective view of a developing unit  54 ; 
       FIG. 4  is a section view showing main structural components of the developing unit  54 ; 
       FIG. 5  is a diagram showing a holder  620  supporting a developing roller  510 ; 
       FIG. 6  is a diagram showing the holder  620  not supporting a developing roller  510 ; 
       FIG. 7  is a diagram showing the lower frame  630 ; 
       FIG. 8  is a diagram showing the front frame  640 ; 
       FIG. 9  is a diagram showing the rear frame  650 ; 
       FIG. 10  is a diagram showing the upper frame  660 ; 
       FIG. 11  is a diagram showing the gear-supporting shaft  670 ; 
       FIG. 12  is a diagram showing the configuration in the periphery of the gear-supporting shaft  670 ; 
       FIG. 13  is a schematic diagram for describing the procedure according to which the holder  620  is assembled; 
       FIG. 14  is a schematic diagram for describing a holder  920  according to a comparative example; 
       FIG. 15A  is a diagram showing a second frame  940  before a first bent section  940   a  and a second bent section  940   b  are formed therein,  FIG. 15B  is a diagram showing the second frame  940  having the first bent section  940   a  formed therein, and  FIG. 15C  is a diagram showing the second frame  940  having the first bent section  940   a  and the second bent section  940   b  formed therein; 
       FIG. 16  is a schematic diagram showing another embodiment of the holder  620 ; 
       FIG. 17  is a diagram for describing the configuration of the driving section of the developing unit  54 ; 
       FIG. 18  is a diagram showing the configuration in the periphery of the gear-supporting shaft  670  according to a second embodiment; 
       FIG. 19  is a diagram for describing another example of the second embodiment; 
       FIG. 20  is a perspective view of a developing unit  3054  according to a third embodiment; 
       FIG. 21  is a section view showing main structural components of the developing unit  3054  according to the third embodiment; 
       FIG. 22  is a perspective view of a holder unit  3610  according to the third embodiment; 
       FIG. 23  is a perspective view of a holder  3620  according to the third embodiment; 
       FIG. 24A  shows the state of connection between the blade-supporting metal plate  3630  and the second side metal plate  3650 ,  FIG. 24B  shows the state of connection between the blade-supporting metal plate  3630  and the first side metal plate  3640 ,  FIG. 24C  shows a state of connection between the upper-seal-supporting metal plate  3660  and the second side metal plate  3650 , and  FIG. 24D  shows the state of connection between the upper-seal-supporting metal plate  3660  and the first side metal plate  3640 ; 
       FIG. 25  is a perspective view of the blade-supporting metal plate  3630  according to the third embodiment; 
       FIG. 26  is a perspective view showing a state in which the restriction blade  3560  is supported by the blade-supporting metal plate  3630  according to the third embodiment; 
       FIG. 27  is a schematic diagram for describing how the attachment position is adjusted according to the third embodiment; 
       FIG. 28  is a flowchart showing a method of assembling the holder  3620  according to the third embodiment; 
       FIG. 29  is a diagram for describing a comparative example of the third embodiment; 
       FIG. 30  is a diagram showing another example of the third embodiment; 
       FIG. 31  is an explanatory drawing showing an external structure of an image forming system; and 
       FIG. 32  is a block diagram showing a configuration of the image forming system shown in  FIG. 31 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   At least the following matters will become clear by the explanation in the present specification and the description of the accompanying drawings. 
   (1) A developing device comprises: a developer containing section that is for containing a developer and that has a predetermined coefficient of thermal expansion; a developing roller for bearing the developer contained in the developer containing section; a roller-supporting member that is for rotatably supporting the developing roller, that has a coefficient of thermal expansion which is different from the coefficient of thermal expansion of the developer containing section, and that is structured by connecting at least three members; and a gap for preventing the roller-supporting member and the developer containing section from interfering with one another when the roller-supporting member and the developer containing section expand/contract due to a change in temperature. 
   With this developing device, the freedom (flexibility) in assembling the roller-supporting member increases, and even when there are variations in size of the members that form the roller-supporting member due to individual differences, it becomes possible to assemble the roller-supporting member such that those variations in size of the members are absorbed. Therefore, it becomes possible to structure the roller-supporting member in a desired size with satisfactory precision. 
   Further, in this developing device, when the at least three members are connected to structure the roller-supporting member, a state of connection among the members may be adjusted such that the roller-supporting member has a predetermined size. 
   With this developing device, the state of connection among the members is adjusted such that the roller-supporting member has a predetermined size, even when there are variations in size of the members that form the roller-supporting member due to individual differences. Therefore, it becomes possible to structure the roller-supporting member in a desired size with high precision. 
   Further, in this developing device, the roller-supporting member may be mounted to the developer containing section such that a longitudinal direction of the roller-supporting member is arranged in a longitudinal direction of the developer containing section; and the developing device may have a gap for preventing the roller-supporting member and the developer containing section from interfering with one another when the roller-supporting member and the developer containing section expand/contract in their longitudinal direction due to a change in temperature. 
   The length of the roller-supporting member and the developer containing section is longer in their longitudinal direction than in their lateral direction. Therefore, the amount of expansion/contraction due to a change in temperature becomes larger in the longitudinal direction than in the lateral direction. In view of this, developing devices are often provide with a gap for preventing the roller-supporting member and the developer containing section from interfering with one another when they expand/contract in their longitudinal direction due to a change in temperature. In this way, when the roller-supporting member is structured by connecting at least three members, it becomes possible to set the length in the longitudinal direction of the roller-supporting member to a desired size such that the developer containing section and the roller-supporting member do not interfere with one another even when they expand/contract in the longitudinal direction due to a change in temperature. 
   Further, in this developing device, the roller-supporting member may be structured by connecting together the following four members: a first supporting member that is arranged in a lateral direction intersecting with the longitudinal direction of the roller-supporting member and that is for supporting one end of the developing roller, a second supporting member that is arranged in the lateral direction and that is for supporting the other end of the developing roller, and a first longitudinal member and a second longitudinal member that are each connected to both the first supporting member and the second supporting member and that are arranged in the longitudinal direction. 
   With this developing device, since the roller-supporting member is structured by connecting four members, it becomes possible to increase the freedom (flexibility) in assembling the roller-supporting member and structure the roller-supporting member such that the length in the longitudinal direction of the roller-supporting member is set to a desired size. 
   Further, in this developing device, the developing device may have a restriction blade for restricting a thickness of a layer of the developer borne by the developing roller; and the second longitudinal member may be a blade-supporting member for supporting the restriction blade. 
   It is necessary to control the position between the developing roller and the restriction blade with satisfactory precision in order to restrict the thickness of the layer of the developer borne on the developing roller. With the above structure, it is possible to structure the roller-supporting member such that the positioning between the developing roller and the restriction blade is performed with high precision when the roller-supporting member is made of four members. 
   Further, in this developing device, when connecting the four members, a state of connection of the first supporting member and the second supporting member with respect to the blade-supporting member may be adjusted. 
   With this developing device, it becomes possible to adjust the position between the developing roller and the restriction blade with even higher precision by adjusting the state of connection of the first supporting member and the second supporting member, which support the developing roller, with respect to the blade-supporting member, which supports the restriction blade. 
   Further, in this developing device, a roller gear for rotating the developing roller with a drive force transmitted from a drive source may be provided on the one end of the developing roller; and the gap may exist between a side surface of the second supporting member that intersects with the longitudinal direction, and an opposition surface of the developer containing section that is in opposition to the side surface. 
   With this developing device, the gap between the roller-supporting member and the developer containing section is provided between the side surface of the second supporting member and the opposition surface of the developer containing section, that is, on the opposite side from the driving section where the roller gear is located. Therefore, it is possible to prevent the driving section from being affected. 
   Further, in this developing device, the second longitudinal member and the first supporting member may be connected with a screw, the second longitudinal member and the second supporting member may be connected with a screw, and the first supporting member and the first longitudinal member may be connected with a screw; and the second supporting member and first longitudinal member do not have to be connected with a screw. 
   With this developing device, even when the second supporting member and first longitudinal member are not connected with a screw, the second longitudinal member and the first supporting member, the second longitudinal member and the second supporting member, and the first supporting member and the first longitudinal member are connected with screws, respectively. Therefore, the function of the roller-supporting member, which is to support the developing roller, can be achieved. Further, by not connecting the second supporting member and first longitudinal member with a screw, the time required for assembling the roller-supporting member can be shortened. 
   Further, in this developing device, a projection may be provided at an end of the first longitudinal member that is connected to the second supporting member; a hole may be provided in the second supporting member; and the projection may be fitted into the hole. 
   With this developing device, it becomes possible to set the length in the longitudinal direction of the roller-supporting member to a desired size, even when there are variations in size in the longitudinal direction of the first longitudinal member due to individual differences. 
   Further, in this developing device, the developer containing section may be made of resin, and the roller-supporting member may be made of metal. 
   Often, the developer containing section is made of resin to achieve weight reduction, and the roller-supporting member is made of metal to hold the developing roller reliably. However, the difference in the coefficient of thermal expansion between resin and metal is larger than the difference in the coefficient of thermal expansion between two resin components. Therefore, the resin-made developer containing section and the metal-made roller-supporting member are more likely to interfere with one another due to a change in temperature. Thus, the effect of the present invention, i.e., the effect of allowing the roller-supporting member to be structured in a desired size, is achieved more advantageously. 
   It is also possible to achieve a developing device comprising: a developer containing section that is for containing a developer and that has a predetermined coefficient of thermal expansion; a developing roller for bearing the developer contained in the developer containing section; a roller-supporting member that is for rotatably supporting the developing roller, that has a coefficient of thermal expansion which is different from the coefficient of thermal expansion of the developer containing section, and that is structured by connecting at least three members; and a gap for preventing the roller-supporting member and the developer containing section from interfering with one another when the roller-supporting member and the developer containing section expand/contract due to a change in temperature; wherein, when the at least three members are connected to structure the roller-supporting member, a state of connection among the members is adjusted such that the roller-supporting member has a predetermined size; wherein the roller-supporting member is mounted to the developer containing section such that a longitudinal direction of the roller-supporting member is arranged in a longitudinal direction of the developer containing section; wherein the developing device has a gap for preventing the roller-supporting member and the developer containing section from interfering with one another when the roller-supporting member and the developer containing section expand/contract in their longitudinal direction due to a change in temperature; wherein the roller-supporting member is structured by connecting together the following four members: a first supporting member that is arranged in a lateral direction intersecting with the longitudinal direction of the roller-supporting member and that is for supporting one end of the developing roller, a second supporting member that is arranged in the lateral direction and that is for supporting the other end of the developing roller, and a first longitudinal member and a second longitudinal member that are each connected to both the first supporting member and the second supporting member and that are arranged in the longitudinal direction; wherein the developing device has a restriction blade for restricting a thickness of a layer of the developer borne by the developing roller; wherein the second longitudinal member is a blade-supporting member for supporting the restriction blade; wherein, when connecting the four members, a state of connection of the first supporting member and the second supporting member with respect to the blade-supporting member is adjusted; wherein a roller gear for rotating the developing roller with a drive force transmitted from a drive source is provided on the one end of the developing roller; wherein the gap exists between a side surface of the second supporting member that intersects with the longitudinal direction, and an opposition surface of the developer containing section that is in opposition to the side surface; wherein the second longitudinal member and the first supporting member are connected with a screw, the second longitudinal member and the second supporting member are connected with a screw, and the first supporting member and the first longitudinal member are connected with a screw; wherein the second supporting member and first longitudinal member are not connected with a screw; wherein a projection is provided at an end of the first longitudinal member that is connected to the second supporting member; wherein a hole is provided in the second supporting member; wherein the projection is fitted into the hole; and wherein the developer containing section is made of resin, and the roller-supporting member is made of metal. 
   With this developing device, the effect of allowing the roller-supporting member to be structured in a desired size with satisfactory precision is achieved most advantageously. 
   It is also possible to achieve an image forming apparatus comprising: an image bearing body for bearing a latent image; and a developing device provided with: a developer containing section that is for containing a developer and that has a predetermined coefficient of thermal expansion; a developing roller for bearing the developer contained in the developer containing section, the developer borne by the developing roller being used to develop the latent image borne by the image bearing body; a roller-supporting member that is for rotatably supporting the developing roller, that has a coefficient of thermal expansion which is different from the coefficient of thermal expansion of the developer containing section, and that is structured by connecting at least three members; and a gap for preventing the roller-supporting member and the developer containing section from interfering with one another when the roller-supporting member and the developer containing section expand/contract due to a change in temperature. 
   In this way, an image forming apparatus that is superior to conventional apparatuses can be achieved because it is provided with a developing device with which it is possible to structure the roller-supporting member in a desired size with satisfactory precision. 
   It is also possible to achieve an image forming system comprising: a computer; and an image forming apparatus that is connectable to the computer and that has an image bearing body for bearing a latent image, and a developing device provided with: a developer containing section that is for containing a developer and that has a predetermined coefficient of thermal expansion; a developing roller for bearing the developer contained in the developer containing section, the developer borne by the developing roller being used to develop the latent image borne by the image bearing body; a roller-supporting member that is for rotatably supporting the developing roller, that has a coefficient of thermal expansion which is different from the coefficient of thermal expansion of the developer containing section, and that is structured by connecting at least three members; and a gap for preventing the roller-supporting member and the developer containing section from interfering with one another when the roller-supporting member and the developer containing section expand/contract due to a change in temperature. 
   In this way, an image forming system that is superior to conventional systems can be achieved because it is provided with a developing device with which it is possible to structure the roller-supporting member in a desired size with satisfactory precision. 
   It is also possible to achieve a method of manufacturing a developing device that is provided with: a developer containing section that is for containing a developer and that has a predetermined coefficient of thermal expansion; a developing roller for bearing the developer contained in the developer containing section; a roller-supporting member that is for rotatably supporting the developing roller and that has a coefficient of thermal expansion which is different from the coefficient of thermal expansion of the developer containing section; and a gap for preventing the roller-supporting member and the developer containing section from interfering with one another when the roller-supporting member and the developer containing section expand/contract due to a change in temperature, the method comprising: preparing at least three members for structuring the roller-supporting member; and connecting the at least three members while adjusting a state of connection among the members such that the roller-supporting member has a predetermined size. 
   With this method of manufacturing a developing device, it is possible to manufacture a developing device with which it is possible to structure the roller-supporting member in a desired size with satisfactory precision. 
   (2) Further, a developing device comprises: a developing roller for bearing a developer; a roller-supporting member that is structured by connecting at least two members and that is for rotatably supporting the developing roller; a roller gear that is provided at one end of the developing roller and that is for rotating the developing roller; an intermediate gear for transmitting a drive force from a drive source to the roller gear; and a gear-supporting shaft for rotatably supporting the intermediate gear, a screw section of the gear-supporting shaft connecting the at least two members that structure the roller-supporting member. 
   With this developing device, it is possible to improve the ease in assembling the roller-supporting member because the gear-supporting shaft also serves as a screw. 
   Further, in this developing device, one of the two members may be a one-end supporting member for rotatably supporting, through a bearing, the one end of the developing roller; and the one-end supporting member may be provided with a shaft hole for mating with the gear-supporting shaft and a bearing hole for mating with the bearing. 
   With this developing device, the positions where the gear-supporting shaft and the bearing are mated with the one-end supporting member can be kept constant. In this way, the distance between the intermediate gear supported by the gear-supporting shaft and the roller gear supported by the developing roller that mates with the bearing can be set to a constant value. Therefore, it becomes possible to control the distance between the intermediate gear and the roller gear with high precision. 
   Further, in this developing device, the intermediate gear may mesh with the roller gear. 
   With this developing device, it is possible to transmit the drive force from the intermediate gear to the roller gear properly when the distance between the intermediate gear and the roller gear is controlled with higher precision. 
   Further, in this developing device, the two members may be: the one-end supporting member, and a longitudinal member that is arranged in a longitudinal direction of the developing roller and that is connected to the one-end supporting member; the gear-supporting shaft may be provided with: a first shaft section for rotatably supporting the intermediate gear, a second shaft section whose diameter is smaller than a diameter of the first shaft section, and the screw section whose diameter is smaller than the diameter of the second shaft section and on which a male screw is formed; the longitudinal member may have a female screw formed therein; and the one-end supporting member and the longitudinal member may be connected by fitting the male screw into the female screw in a state where the second shaft section is fitted into the shaft hole. 
   With this developing device, the one-end supporting member and the longitudinal member are connected by fitting the male screw into the female screw in a state where the second shaft section is fitted into the shaft hole. Therefore, it becomes possible to reliably connect the one-end supporting member and the longitudinal member with a simple structure. 
   Further, in this developing device, the intermediate gear may rotate in a predetermined direction; and a winding direction of a thread of the male screw may be arranged in such a direction that the one-end supporting member and the longitudinal member are tightened together when the gear-supporting shaft is rotated in the predetermined direction. 
   With this developing device, it becomes possible to prevent the male screw of the screw section from loosening from the female screw of the longitudinal member. 
   Further, in this developing device, the developing device may have: a developer containing section for containing a developer, and a sealing member that abuts against the developing roller and that is for preventing the developer from spilling from between the developing roller and the developer containing section; and the sealing member may be supported by the longitudinal member. 
   By fitting the male screw of the gear-supporting shaft, which is supported at a predetermined position with respect to the one-end supporting member through mating of the second shaft section and the shaft hole, into the female screw of the longitudinal member, it is possible to control the attachment position of the longitudinal member with respect to the one-end supporting member with satisfactory precision. In this case, it is possible to properly control the abutment of the sealing member against the developing roller when the sealing member is supported by the longitudinal member, and therefore effectively prevent the developer from spilling from between the developing roller and the developer containing section. 
   Further, in this developing device, the roller-supporting member may be structured by connecting together the following four members: the one-end supporting member, an other-end supporting member for rotatably supporting, through a bearing, an other end of the developing roller, and the longitudinal member and a second longitudinal member that are each connected to both the one-end supporting member and the other-end supporting member and that are arranged in the longitudinal direction. 
   There are cases in which the roller-supporting member is structured of four members in order to rotatably support the developing roller at both ends. In this case, screws are often used to connect the four members, and thus, assembly of the roller-supporting member may become more complicated. If two members that structure the roller-supporting member are connected using a screw section of the gear-supporting shaft, then the effect of allowing improvement in the ease in assembling the roller-supporting member is achieved more advantageously. 
   It is also possible to achieve a developing device comprising: a developing roller for bearing a developer; a roller-supporting member that is structured by connecting at least two members and that is for rotatably supporting the developing roller; a roller gear that is provided at one end of the developing roller and that is for rotating the developing roller; an intermediate gear for transmitting a drive force from a drive source to the roller gear; and a gear-supporting shaft for rotatably supporting the intermediate gear, a screw section of the gear-supporting shaft connecting the at least two members that structure the roller-supporting member; wherein one of the two members is a one-end supporting member for rotatably supporting, through a bearing, the one end of the developing roller; wherein the one-end supporting member is provided with a shaft hole for mating with the gear-supporting shaft and a bearing hole for mating with the bearing; wherein the intermediate gear meshes with the roller gear; wherein the two members are: the one-end supporting member, and a longitudinal member that is arranged in a longitudinal direction of the developing roller and that is connected to the one-end supporting member; wherein the gear-supporting shaft is provided with: a first shaft section for rotatably supporting the intermediate gear, a second shaft section whose diameter is smaller than a diameter of the first shaft section, and the screw section whose diameter is smaller than the diameter of the second shaft section and on which a male screw is formed; wherein the longitudinal member has a female screw formed therein; wherein the one-end supporting member and the longitudinal member are connected by fitting the male screw into the female screw in a state where the second shaft section is fitted into the shaft hole; wherein the intermediate gear rotates in a predetermined direction; wherein a winding direction of a thread of the male screw is arranged in such a direction that the one-end supporting member and the longitudinal member are tightened together when the gear-supporting shaft is rotated in the predetermined direction; wherein the developing device has: a developer containing section for containing a developer, and a sealing member that abuts against the developing roller and that is for preventing the developer from spilling from between the developing roller and the developer containing section; wherein the sealing member is supported by the longitudinal member; and wherein the roller-supporting member is structured by connecting together the following four members: the one-end supporting member, an other-end supporting member for rotatably supporting, through a bearing, an other end of the developing roller, and the longitudinal member and a second longitudinal member that are each connected to both the one-end supporting member and the other-end supporting member and that are arranged in the longitudinal direction. 
   With this developing device, the effect of allowing improvement in the ease in assembling the roller-supporting member is achieved most advantageously. 
   It is also possible to achieve an image forming apparatus comprising: an image bearing body for bearing a latent image; and a developing device provided with: a developing roller for bearing a developer, the developer borne by the developing roller being used to develop the latent image borne by the image bearing body; a roller-supporting member that is structured by connecting at least two members and that is for rotatably supporting the developing roller; a roller gear that is provided at one end of the developing roller and that is for rotating the developing roller; an intermediate gear for transmitting a drive force from a drive source to the roller gear; and a gear-supporting shaft for rotatably supporting the intermediate gear, a screw section of the gear-supporting shaft connecting the at least two members that structure the roller-supporting member. 
   In this way, an image forming apparatus that is superior to conventional apparatuses can be achieved because it is provided with a developing device with which it is possible to improve the ease in assembling the roller-supporting member. 
   It is also possible to achieve an image forming system comprising: a computer; and an image forming apparatus that is connectable to the computer and that has an image bearing body for bearing a latent image, and a developing device provided with: a developing roller for bearing a developer, the developer borne by the developing roller being used to develop the latent image borne by the image bearing body; a roller-supporting member that is structured by connecting at least two members and that is for rotatably supporting the developing roller; a roller gear that is provided at one end of the developing roller and that is for rotating the developing roller; an intermediate gear for transmitting a drive force from a drive source to the roller gear; and a gear-supporting shaft for rotatably supporting the intermediate gear, a screw section of the gear-supporting shaft connecting the at least two members that structure the roller-supporting member. 
   In this way, an image forming system that is superior to conventional systems can be achieved because it is provided with a developing device with which it is possible to improve the ease in assembling the roller-supporting member. 
   (3) Further, a developing device comprises: a developer charging member for charging a developer borne by a developer bearing roller; a bearing-roller-supporting member that is made of metal and that is for rotatably supporting the developer bearing roller; and a charge-supporting member that is made of metal and that is for supporting the developer charging member, the charge-supporting member and the bearing-roller-supporting member being welded through spot welding. 
   With this developing device, since it is possible to prevent the position of the charge-supporting member with respect to the bearing-roller-supporting member from deviating from its proper position when welding together the bearing-roller-supporting member and the charge-supporting member, it becomes possible to arrange the developer charging member in an appropriate position with respect to the developer bearing roller. 
   Further, in this developing device, the spot welding may be laser spot welding. 
   In this way, since it is possible to control the intensity of the laser beam and the irradiation time easily and therefore keep unnecessary heat from being applied to the bearing-roller-supporting member and the charge-supporting member, deformation of the bearing-roller-supporting member and the charge-supporting member due to heat can be inhibited. Thus, it becomes possible to prevent the deviation in position of the charge-supporting member with respect to the bearing-roller-supporting member more effectively. 
   Further, in this developing device, an attachment position where the charge-supporting member is attached to the bearing-roller-supporting member may be adjusted, and after adjusting the attachment position, the charge-supporting member and the bearing-roller-supporting member may be welded through spot welding. 
   In this way, it is possible to prevent the position of the charge-supporting member with respect to the bearing-roller-supporting member from deviating after the attachment position has been adjusted, and therefore arrange the developer charging member in a more appropriate position with respect to the developer bearing roller. 
   Further, in this developing device, the bearing-roller-supporting member may include a one-end supporting member for rotatably supporting one end, in an axial direction, of the developer bearing roller, and an other-end supporting member for rotatably supporting an other end, in the axial direction, of the developer bearing roller; the charge-supporting member may be provided such that a longitudinal direction thereof is arranged in the axial direction of the developer bearing roller; and the charge-supporting member and both the one-end supporting member and the other-end supporting member may be welded through spot welding. 
   In this way, it is possible to prevent the position of the charge-supporting member with respect to the one-end supporting member and the other-end supporting member from deviating, and therefore arrange the developer charging member in a more appropriate position with respect to the developer bearing roller. 
   Further, in this developing device, both ends, in the longitudinal direction, of the charge-supporting member may be bent; and the sections that have been bent may be welded, respectively, through spot welding to the one-end supporting member and the other-end supporting member in a state where the sections that have been bent are placed in contact, respectively, with the one-end supporting member and the other-end supporting member. 
   In a case where the sections on both ends of the charge-supporting member that have been bent and the bearing-roller-supporting member are fastened together with a screw, the position of the charge-supporting member with respect to the bearing-roller-supporting member is more likely to deviate from its proper position due to the turning force etc. for causing the screw to turn. Therefore, the effect of the present invention, i.e., the effect of allowing the developer charging member to be arranged in an appropriate position with respect to the developer bearing roller, is achieved more advantageously. 
   Further, in this developing device, the developer charging member may be provided with an abutting section that abuts against the developer bearing roller. 
   In a case where the abutting section is provided on the developer charging member, it is necessary to arrange the abutting section in an appropriate position with respect to the developer bearing roller to make the electric charge of the developer on the developer bearing roller even. Therefore, the effect of the present invention, i.e., the effect of allowing the developer charging member to be arranged in an appropriate position with respect to the developer bearing roller, is achieved more advantageously. 
   Further, in this developing device, the developer charging member may be provided with an abutment-supporting section whose one end, in a lateral direction, is supported by the charge-supporting member and whose other end is for supporting the abutting section; and the abutment-supporting section and the charge-supporting member may be welded through spot welding. 
   In this case, since the bearing-roller-supporting member and the charge-supporting member, as well as the abutment-supporting section and the charge-supporting member, are welded through the same spot welding technique, the burden of changing the method for welding can be eliminated, and therefore, it becomes possible to improve the workability during manufacturing. 
   Further, in this developing device, the developing device may have a seal-supporting member for supporting a sealing member that prevents the developer from spilling from between the developer bearing roller and a housing that contains the developer; and the seal-supporting member and both the one-end supporting member and the other-end supporting member may be welded through spot welding. 
   In this case, since the charge-supporting member and the seal-supporting member are connected to both the one-end supporting member and the other-end supporting member through spot welding, it becomes possible to increase the strength in connecting the four members. 
   It is also possible to achieve a developing device comprising: a developer charging member for charging a developer borne by a developer bearing roller; a bearing-roller-supporting member that is made of metal and that is for rotatably supporting the developer bearing roller; and a charge-supporting member that is made of metal and that is for supporting the developer charging member; wherein an attachment position where the charge-supporting member is attached to the bearing-roller-supporting member is adjusted, and after adjusting the attachment position, the charge-supporting member and the bearing-roller-supporting member are welded through laser spot welding; wherein the bearing-roller-supporting member includes a one-end supporting member for rotatably supporting one end, in an axial direction, of the developer bearing roller, and an other-end supporting member for rotatably supporting an other end, in the axial direction, of the developer bearing roller; wherein the charge-supporting member is provided such that a longitudinal direction thereof is arranged in the axial direction of the developer bearing roller; wherein the charge-supporting member and both the one-end supporting member and the other-end supporting member are welded through laser spot welding; wherein both ends, in the longitudinal direction, of the charge-supporting member are bent; wherein the sections that have been bent are welded, respectively, through laser spot welding to the one-end supporting member and the other-end supporting member in a state where the sections that have been bent are placed in contact, respectively, with the one-end supporting member and the other-end supporting member; wherein the developer charging member is provided with an abutting section that abuts against the developer bearing roller; wherein the developer charging member is provided with an abutment-supporting section whose one end, in a lateral direction, is supported by the charge-supporting member and whose other end is for supporting the abutting section; wherein the abutment-supporting section and the charge-supporting member are welded through laser spot welding; wherein the developing device has a seal-supporting member for supporting a sealing member that prevents the developer from spilling from between the developer bearing roller and a housing that contains the developer; and wherein the seal-supporting member and both the one-end supporting member and the other-end supporting member are welded through laser spot welding. 
   With this developing device, the effect of allowing the developer charging member to be arranged in an appropriate position with respect to the developer bearing roller is achieved most advantageously. 
   It is also possible to achieve an image forming apparatus comprising: an image bearing body for bearing a latent image; and a developing device provided with: a developer charging member for charging a developer borne by a developer bearing roller, the developer borne by the developer bearing roller being used to develop the latent image borne by the image bearing body; a bearing-roller-supporting member that is made of metal and that is for rotatably supporting the developer bearing roller; and a charge-supporting member that is made of metal and that is for supporting the developer charging member, the charge-supporting member and the bearing-roller-supporting member being welded through spot welding. 
   In this way, an image forming apparatus that is superior to conventional apparatuses can be achieved because it is provided with a developing device with which it is possible to arrange the developer charging member in an appropriate position with respect to the developer bearing roller. 
   It is also possible to achieve an image forming system comprising: a computer; and an image forming apparatus that is connectable to the computer and that has an image bearing body for bearing a latent image, and a developing device provided with: a developer charging member for charging a developer borne by a developer bearing roller, the developer borne by the developer bearing roller being used to develop the latent image borne by the image bearing body; a bearing-roller-supporting member that is made of metal and that is for rotatably supporting the developer bearing roller; and a charge-supporting member that is made of metal and that is for supporting the developer charging member, the charge-supporting member and the bearing-roller-supporting member being welded through spot welding. 
   In this way, an image forming system that is superior to conventional systems can be achieved because it is provided with a developing device with which it is possible to arrange the developer charging member in an appropriate position with respect to the developer bearing roller. 
   It is also possible to achieve a method of manufacturing a developing device, comprising: supporting a developer charging member with a charge-supporting member, the developer charging member being provided for charging a developer borne by a developer bearing roller, and the charge-supporting member being made of metal and provided for supporting the developer charging member; adjusting an attachment position where the charge-supporting member, which supports the developer charging member, is attached to a bearing-roller-supporting member that is made of metal and that is provided for rotatably supporting the developer bearing roller; and after adjusting the attachment position, welding the bearing-roller-supporting member and the charge-supporting member through spot welding. 
   With this method of manufacturing a developing device, it is possible to arrange the developer charging member in an appropriate position with respect to the developer bearing roller. 
   Further, in this method of manufacturing a developing device, the spot welding may be laser spot welding. 
   In this way, since it is possible to control the intensity of the laser beam and the irradiation time easily and therefore keep unnecessary heat from being applied to the bearing-roller-supporting member and the charge-supporting member, deformation of the bearing-roller-supporting member and the charge-supporting member due to heat can be inhibited. Thus, it becomes possible to prevent the deviation in position of the charge-supporting member with respect to the bearing-roller-supporting member more effectively. 
   Further, in this method of manufacturing a developing device, the bearing-roller-supporting member may include a one-end supporting member for rotatably supporting one end, in an axial direction, of the developer bearing roller, and an other-end supporting member for rotatably supporting an other end, in the axial direction, of the developer bearing roller; the charge-supporting member may be provided such that a longitudinal direction thereof is arranged in the axial direction of the developer bearing roller; both ends, in the longitudinal direction, of the charge-supporting member may be bent; and in the step of welding the bearing-roller-supporting member and the charge-supporting member through spot welding, the sections that have been bent may be welded, respectively, through spot welding to the one-end supporting member and the other-end supporting member in a state where the sections that have been bent are placed in contact, respectively, with the one-end supporting member and the other-end supporting member. 
   In a case where the sections on both ends of the charge-supporting member that have been bent and the bearing-roller-supporting member are fastened together with a screw, the position of the charge-supporting member with respect to the bearing-roller-supporting member is more likely to deviate from its proper position due to the turning force etc. for causing the screw to turn. Therefore, the effect of the present invention, i.e., the effect of allowing the developer charging member to be arranged in an appropriate position with respect to the developer bearing roller, is achieved more advantageously. 
   Further, in this method of manufacturing a developing device, the developer charging member and the charge-supporting member may be welded through spot welding in the step of supporting the developer charging member with the charge-supporting member. 
   In this case, since the bearing-roller-supporting member and the charge-supporting member, as well as the developer charging member and the charge-supporting member, are welded through the same spot welding technique, the burden of changing the method for welding can be eliminated, and therefore, it becomes possible to improve the workability during manufacturing. 
   Further, in this method of manufacturing a developing device, the developer charging member may be provided with an abutting section that abuts against the developer bearing roller; the bearing-roller-supporting member may be provided with a roller-supporting hole for supporting the developer bearing roller; and in the step of adjusting the attachment position, the attachment position may be adjusted such that a distance between an end of the abutting section and a center of the roller-supporting hole takes a predetermined value. 
   In this way, it becomes possible to arrange the charge-supporting member in an appropriate position with respect to the bearing-roller-supporting member with higher precision compared to adjusting the attachment position in a state where the abutting section is made to abut against the developer bearing roller. 
   &lt;&lt;&lt;Overview of Image Forming Apparatus (Laser Beam Printer)&gt;&gt;&gt; 
   Next, using  FIG. 1 , an outline of a laser beam printer  10  (referred to also as “printer  10 ” below), which is an example of an image forming apparatus, is described.  FIG. 1  is a diagram showing main structural components constructing the printer  10 . It should be noted that in  FIG. 1 , the vertical direction is shown by the arrow, and, for example, a paper supply tray  92  is arranged at a lower section of the printer  10 , and a fusing unit  90  is arranged at an upper section of the printer  10 . 
   &lt;Overall Configuration of Image Forming Apparatus&gt; 
   As shown in  FIG. 1 , the printer  10  according to the present embodiment includes a charging unit  30 , an exposing unit  40 , a rotating body  50 , a first transferring unit  60 , an intermediate transferring body  70 , and a cleaning unit  75 . These units are arranged in the direction of rotation of a photoconductor  20 , which serves as an example of an image bearing body for bearing a latent image. The printer  10  further includes a second transferring unit  80 , a fusing unit  90 , a displaying unit  95  constructed of a liquid-crystal panel and serving as means for making notifications to the user etc., and a control unit  100  for controlling these units etc. and managing the operations as a printer. 
   The photoconductor  20  has a cylindrical conductive base and a photoconductive layer formed on the outer peripheral surface of the conductive base, and it is rotatable about its central axis. In the present embodiment, the photoconductor  20  rotates clockwise, as shown by the arrow in  FIG. 1 . 
   The charging unit  30  is a device for charging the photoconductor  20 . The exposing unit  40  is a device for forming a latent image on the charged photoconductor  20  by radiating a laser beam thereon. The exposing unit  40  has, for example, a semiconductor laser, a polygon mirror, and an F-θ lens, and radiates a modulated laser beam onto the charged photoconductor  20  according to image signals having been input from a not-shown host computer such as a personal computer or a word processor. 
   The rotating body  50  is a device for developing the latent image formed on the photoconductor  20  using black (K) toner contained in a black developing unit  51 , magenta (M) toner contained in a magenta developing unit  52 , cyan (C) toner contained in a cyan developing unit  53 , and yellow (Y) toner contained in a yellow developing unit  54  ( 3054  in the third embodiment). 
   In the present embodiment, the rotating body  50  rotates to allow the positions of the four developing units  51 ,  52 ,  53 , and  54  ( 3054 ), which serve as an example of developing devices, to, be moved. More specifically, the rotating body  50  holds the four developing units  51 ,  52 ,  53 , and  54  ( 3054 ) with four attach/detach sections  50   a ,  50   b ,  50   c , and  50   d , respectively, and the four developing units  51 ,  52 ,  53 , and  54  ( 3054 ) can be rotated about a rotating shaft  50   e  while maintaining their relative positions. A different one of the developing units is made to selectively oppose the photoconductor  20  each time the photoconductor  20  makes one revolution, thereby successively developing the latent image formed on the photoconductor  20  using the toner T, which is an example of a developer, contained in each of the developing units  51 ,  52 ,  53 , and  54  ( 3054 ). It should be noted that details on the developing units are described further below. 
   The first transferring unit  60  is a device for transferring, onto the intermediate transferring body  70 , a single-color toner image formed on the photoconductor  20 . When toner images of four colors are successively transferred in a superposed manner, a full-color toner image is formed on the intermediate transferring body  70 . The intermediate transferring body  70  is an endless belt that is driven to rotate at substantially the same circumferential speed as the photoconductor  20 . The second transferring unit  80  is a device for transferring the single-color toner image, or the full-color toner image, formed on the intermediate transferring body  70  onto a recording medium such as paper, film, and cloth. 
   The fusing unit  90  is a device for fusing the single-color toner image or the full-color toner image, which has been transferred to the recording medium, onto the recording medium such as paper to make it into a permanent image. 
   The cleaning unit  75  is a device that is provided between the first transferring unit  60  and the charging unit  30 , that has a rubber cleaning blade  76  made to abut against the surface of the photoconductor  20 , and that is for removing the toner remaining on the photoconductor  20  by scraping it off with the cleaning blade  76  after the toner image has been transferred on to the intermediate transferring body  70  by the first transferring unit  60 . 
   The control unit  100  includes a main controller  101  and a unit controller  102  as shown in  FIG. 2 . Image signals are input to the main controller  101 , and according to instructions based on these image signals, the unit controller  102  controls each of the above-mentioned units etc. to form an image. 
   &lt;Operation of Image Forming Apparatus&gt; 
   Next, operations of the printer  10  structured as above are described, referring also to other structural components. 
   When image signals are input from the not-shown host computer to the main controller  101  of the printer  10  through an interface (I/F)  112 , then the photoconductor  20 , a developing roller, which is provided in each of the developing units  51 ,  52 ,  53 , and  54  ( 3054 ), and the intermediate transferring body  70  rotate under the control of the unit controller  102  according to the instructions from the main controller  101 . While being rotated, the photoconductor  20  is successively charged by the charging unit  30  at a charging position. 
   With the rotation of the photoconductor  20 , the charged area of the photoconductor  20  reaches an exposing position. A latent image that corresponds to the image information for the first color, for example, yellow Y, is formed in that area by the exposing unit  40 . The rotating body  50  positions the yellow developing unit  54  ( 3054 ), which contains yellow (Y) toner, at the developing position opposing the photoconductor  20 . 
   With the rotation of the photoconductor  20 , the latent image formed on the photoconductor  20  reaches the developing position, and is developed with the yellow toner by the yellow developing unit  54  ( 3054 ). Thus, a yellow toner image is formed on the photoconductor  20 . 
   With the rotation of the photoconductor  20 , the yellow toner image formed on the photoconductor  20  reaches a first transferring position, and is transferred onto the intermediate transferring body  70  by the first transferring unit  60 . At this time, a first transferring voltage, which is in an opposite polarity to the polarity to which the toner is charged, is applied to the first transferring unit  60 . It should be noted that, during this process, the second transferring unit  80  is kept separated from the intermediate transferring body  70 . 
   By repeating the above-mentioned processes for the second, the third, and the fourth colors, toner images in four colors corresponding to the respective image signals are transferred to the intermediate transferring body  70  in a superimposed manner. As a result, a full-color toner image is formed on the intermediate transferring body  70 . 
   With the rotation of the intermediate transferring body  70 , the full-color toner image formed on the intermediate transferring body  70  reaches a second transferring position, and is transferred onto a recording medium by the second transferring unit  80 . It should be noted that the recording medium is carried from the paper supply tray  92  to the second transferring unit  80  via the paper-feed roller  94  and resisting rollers  96 . During transferring operations, a second transferring voltage is applied to the second transferring unit  80  and also the unit  80  is pressed against the intermediate transferring body  70 . 
   The full-color toner image transferred onto the recording medium is heated and pressurized by the fusing unit  90  and fused to the recording medium. 
   On the other hand, after the photoconductor  20  passes the first transferring position, the toner adhering to the surface of the photoconductor  20  is scraped off by the cleaning blade  76  that is supported on the cleaning unit  75 , and the photoconductor  20  is prepared for charging for the next latent image to be formed. The scraped-off toner is collected into a remaining-toner collector of the cleaning unit  75 . 
   &lt;&lt;&lt;Overview of Control Unit&gt;&gt;&gt; 
   Next, a configuration of the control unit  100  is described with reference to  FIG. 2 . The main controller  101  of the control unit  100  is connected to a host computer via the interface  112 , and is provided with an image memory  113  for storing the image signals that have been input from the host computer. 
   The unit controller  102  is electrically connected to the units in the body of the apparatus (i.e., the charging unit  30 , the exposing unit  40 , the rotating body  50 , the first transferring unit  60 , the cleaning unit  75 , the second transferring unit  80 , the fusing unit  90 , and the displaying unit  95 ), and it detects the state of the units by receiving signals from sensors provided in those units, and controls them based on the signals that are input from the main controller  101 . 
   &lt;&lt;&lt;First Embodiment&gt;&gt;&gt; 
   ===(1) Overview of Developing Unit=== 
   Next, using  FIG. 3  and  FIG. 4 , an example of a configuration of a developing unit according to a first embodiment will be described. It should be noted that the configuration of the overall image forming apparatus and the configuration of the control unit are the same for the present first embodiment and the second and third embodiments described later on.  FIG. 3  is a perspective view of a developing unit  54 .  FIG. 4  is a section view showing main structural components of the developing unit  54 . It should be noted that the section view shown in  FIG. 4  is a cross section of the developing unit  54  bisected by a plane perpendicular to the longitudinal direction shown in  FIG. 3 . Further, in  FIG. 4 , the arrow indicates the vertical direction as in  FIG. 1 , and, for example, the central axis of the developing roller  510  is located below the central axis of the photoconductor  20 . Further, in  FIG. 4 , the yellow developing unit  54  is shown to be in a state in which it is positioned at the developing position opposing the photoconductor  20 . 
   To the rotating body  50 , it is possible to attach: the black developing unit  51  containing black (K) toner; the magenta developing unit  52  containing magenta (M) toner; the cyan developing unit  53  containing cyan (C) toner; and the yellow developing unit  54  containing yellow (Y) toner. Since the configuration of the developing units is the same, explanation will be made only about the yellow developing unit  54  below. 
   &lt;Internal Configuration of Developing Unit&gt; 
   The yellow developing unit  54  has the developing roller  510 , a toner containing space  530 , a housing  540  which serves as an example of a developer container, a toner supplying roller  550 , a restriction blade  560 , and a holder unit  610 . 
   The developing roller  510  bears toner T and delivers it to the developing position opposing the photoconductor  20 . The developing roller  510  is made of metal and, for example, it is manufactured from aluminum alloy such as aluminum alloy  5056  or aluminum alloy  6063 , or iron alloy such as STKM, and the roller  510  is plated with, for example, nickel plating or chromium plating, as necessary. 
   Further, as shown in  FIG. 3 , the developing roller  510  is supported at both ends in its longitudinal direction and is rotatable about its central axis. As shown in  FIG. 4 , the developing roller  510  rotates in the opposite direction (counterclockwise in  FIG. 4 ) to the rotating direction of the photoconductor  20  (clockwise in  FIG. 4 ). The central axis of the roller  510  is located below the central axis of the photoconductor  20 . 
   Further, as shown in  FIG. 4 , in a state where the yellow developing unit  54  opposes the photoconductor  20 , there is a gap between the developing roller  510  and the photoconductor  20 . That is, the yellow developing unit  54  develops the latent image formed on the photoconductor  20  in a non-contacting state. It should be noted that an alternating field is generated between the developing roller  510  and the photoconductor  20  upon development of the latent image formed on the photoconductor  20 . 
   The holder unit  610  is structured of, for example, a holder  620  made of metal (such as aluminum alloy, SECC, and SPCC+Ni (nickel) plating) for supporting the developing roller  510 , and an upper seal  520 , which is an example of a sealing member, that is supported by the holder  620 . 
   The upper seal  520  prevents the toner T in the yellow developing unit  54  from spilling out therefrom, and also collects the toner T, which is on the developing roller  510  that has passed the developing position, into the developing device without scraping it off. The upper seal  520  is a seal made of, for example, polyethylene film. 
   A seal-urging member  524  made of, for example, Moltoprene is provided on one side of the upper seal  520  opposite from the side of the developing roller  510 . The upper seal  520  is pressed against the developing roller  510  by the elastic force of the seal-urging member  524 . 
   Further, the abutting position at which the upper seal  520  abuts against the developing roller  510  is located above the central axis of the developing roller  510 . 
   It should be noted that the holder unit  610  will be described in detail further below. 
   The housing  540  is manufactured by welding together a plurality of integrally-molded housing sections, that is, an upper housing section  542  and a lower housing section  544 . The inside of the housing  540  is divided into two toner containing spaces  530 , namely, the first toner containing space  530   a  and the second toner containing space  530   b , by a partitioning wall  545  that is for partitioning the toner T and that protrudes inwards (in the up/down direction of  FIG. 4 ) from the inner wall. It should be noted that an opening  572  is located at the lower section of the housing  540 , and the developing roller  510  is arranged with respect to the opening  572  such that a portion of the roller  510  is exposed from the opening. The housing  540  is made of resin (such as ABS (acrylonitrile butadiene styrene) resin or PS (polystyrene) resin). 
   The toner containing spaces  530  may be provided with a stirring member for stirring the toner T. In the present embodiment, however, no stirring member is provided in the toner containing spaces  530  because each of the developing units (i.e., the black developing unit  51 , the magenta developing unit  52 , the cyan developing unit  53 , and the yellow developing unit  54 ) is rotated with the rotation of the rotating body  50  and the toner T in each developing unit is thereby stirred. 
   The toner supplying roller  550  is provided in the first toner containing space  530   a  described above and supplies the toner T contained in the first toner containing space  530   a  to the developing roller  510 . The toner supplying roller  550  is made of, for example, polyurethane foam, and is made to abut against the developing roller  510  in an elastically deformed state. The toner supplying roller  550  is arranged at a lower section of the toner containing space  530 . The toner T contained in the toner containing spaces  530  is supplied to the developing roller  510  by the toner supplying roller  550  at the lower section of the toner containing space  530 . 
   The toner supplying roller  550  is rotatable about its central axis. The central axis of the toner supplying roller  550  is situated below the central axis of rotation of the developing roller  510 . Further, the toner supplying roller  550  rotates in the opposite direction (clockwise in  FIG. 4 ) to the rotating direction of the developing roller  510  (counterclockwise in  FIG. 4 ). It should be noted that the toner supplying roller  550  has the function of supplying the toner T contained in the toner containing space  530  to the developing roller  510  as well as the function of stripping off, from the developing roller  510 , the toner T remaining on the developing roller  510  after development. 
   The restriction blade  560  gives an electric charge to the toner T borne by the developing roller  510  as well as restricts the thickness of the layer of the toner T borne by the developing roller  510 . The restriction blade  560  includes a rubber section  560   a  and a rubber-supporting section  560   b.    
   The rubber section  560   a  is made of, for example, silicone rubber or urethane rubber. The rubber-supporting section  560   b  is a thin plate that is made of, for example, phosphor bronze or stainless steel, and that has a spring-like characteristic. The rubber section  560   a  is supported by the rubber-supporting section  560   b , and the rubber-supporting section  560   b  is supported at one end by the holder  620 . 
   Further, a blade-backing member  570  made of, for example, Moltoprene is provided on one side of the restriction blade  560  opposite from the side of the developing roller  510 . 
   The rubber section  560   a  is pressed against the developing roller  510  by the elastic force caused by the flexure of the rubber-supporting section  560   b . Further, the blade-backing member  570  prevents the toner T from entering in between the rubber-supporting section  560   b  and the housing  540 , stabilizes the elastic force caused by the flexure of the rubber-supporting section  560   b , and also, applies force to the rubber section  560   a  from the back thereof towards the developing roller  510  to press the rubber section  560   a  against the developing roller  510 . In this way, the blade-backing member  570  makes the rubber section  560   a  abut against the developing roller  510  more evenly. 
   The end of the restricting blade  560  opposite from the end that is being supported by the holder  620 , i.e., the tip end of the restriction blade  560 , is not placed in contact with the developing roller  510 ; rather, a section at a predetermined distance from the tip end contacts, with some breadth, the developing roller  510 . That is, the restriction blade  560  does not abut against the developing roller  510  at its edge, but abuts against the roller  510  near its central portion. Further, the restriction blade  560  is arranged so that its tip end faces towards the upstream side of the rotating direction of the developing roller  510 , and thus, makes a so-called counter-abutment with respect to the roller  510 . It should be noted that the abutting position at which the restriction blade  560  abuts against the developing roller  510  is below the central axis of the developing roller  510  and is also below the central axis of the toner supplying roller  550 . 
   &lt;Configuration of Driving Section&gt; 
   Next the configuration of the driving section of the yellow developing unit  54  is described with reference to  FIG. 3  and  FIG. 17 .  FIG. 17  is a diagram for describing the configuration of the driving section of the developing unit  54 . 
   As shown in  FIG. 3 , the driving section of the developing unit  54  is provided with a developing-roller gear  512  which is for rotating the developing roller  510  and which is an example of a roller gear, a supplying-roller gear (not shown) for rotating the toner supplying roller  550 , and an idler gear  511  which is an example of an intermediate gear. 
   The developing-roller gear  512  is provided on the side of one end of the developing roller  510 , and rotates the developing roller  510  with the drive force transmitted from the drive motor  501 , which is an example of a drive source. It should be noted that the developing-roller gear  512  meshes with the supplying-roller gear provided on the side of one end of the toner supplying roller  550 . 
   The idler gear  511  is rotatably supported by the gear-supporting shaft  670 , which is described further below, and transmits the drive force from the drive motor  501  to the developing-roller gear  512 . It should be noted that the idler gear  511  meshes with the developing-roller gear  512 . 
   Next, the way in which the drive force is transmitted from the drive motor  501  to the developing-roller gear  512  is described. As shown in  FIG. 17 , a drive gear  502  is attached to the motor shaft of the drive motor  501 . The gear wheel train between the drive gear  502  and the developing-roller gear  512  include a development input gear  505  that meshes with the drive gear  502 , a relay gear  509  that meshes with the development input gear  505 , and the idler gear  511  that meshes with the relay gear  509 . 
   In this way, the developing roller  510  rotates when the drive motor  501  is rotated. 
   &lt;Operation of Developing Unit&gt; 
   In the yellow developing unit  54  structured as above, the toner supplying roller  550  supplies the toner T contained in the toner containing spaces  530  to the developing roller  510 . 
   With the rotation of the developing roller  510 , the toner T, which has been supplied to the developing roller  510 , reaches the abutting position of the restriction blade  560 ; then, as the toner T passes the abutting position, the toner is electrically charged and its layer thickness is restricted. 
   With further rotation of the developing roller  510 , the toner T on the developing roller  510  whose layer thickness has been restricted reaches the developing position opposing the photoconductor  20 ; then, under the alternating field, the toner T is used at the developing position for developing the latent image formed on the photoconductor  20 . 
   With further rotation of the developing roller  510 , the toner T on the developing roller  510 , which has passed the developing position, passes the upper seal  520  and is collected into the developing unit by the upper seal  520  without being scraped off. 
   Then, the toner T that still remains on the developing roller  510  can be stripped off by the toner supplying roller  550 . 
   ===(1) Overview of Holder Unit=== 
   &lt;Configuration of the Holder Unit  610 &gt; 
   Next, with reference to  FIG. 3  to  FIG. 6 , the configuration of the holder unit  610  is described.  FIG. 5  is a diagram showing the holder unit  610  supporting the developing roller  510 . FIG.  6  is a diagram showing the holder  620 . 
   The holder unit  610  includes the holder  620 , which is an example of a roller-supporting member, that rotatably supports the developing roller  510 , the upper seal  520 , the restriction blade  560 , and the end seals  527 . 
   The holder  620  supports one end of the developing roller  510  via a bearing  681  and supports the other end of the developing roller  510  via a bearing  682 . A gap S (see  FIG. 3 ) exists between the holder  620  and the housing  540 . It should be noted that the configuration of the holder  620  will be described in detail further below. 
   The upper seal  520  prevents the toner T from spilling from between the developing roller  510  and a portion of the housing  540  that forms the upper edge of the opening  572  (see  FIG. 4 ). 
   The restriction blade  560  has the function of preventing the toner T from spilling from between the developing roller  510  a portion of the housing  540  that forms the lower edge of the opening  572  (see  FIG. 4 ). 
   The end seals  527  are fixed to the rubber-supporting section  560 b of the restriction blade  560  and prevent the toner T from spilling in the axial direction of the developing roller  510  at both ends thereof. 
   The holder unit  610  structured as above is mounted to the housing  540  such that its longitudinal direction is arranged in the longitudinal direction of the housing  540 . 
   &lt;Configuration of the Holder  620 &gt; 
   Next, with reference to  FIG. 5  to  FIG. 12 , the configuration of the holder  620  will be described.  FIG. 7  is a diagram showing the lower frame  630 .  FIG. 8  is a diagram showing the front frame  640 .  FIG. 9  is a diagram showing the rear frame  650 .  FIG. 10  is a diagram showing the upper frame  660 .  FIG. 11  is a diagram showing the gear-supporting shaft  670 .  FIG. 12  is a diagram showing the configuration in the periphery of the gear-supporting shaft  670  according to the present first embodiment. 
   As shown in  FIG. 6 , the holder  620  is made by connecting four members, i.e., a front frame  640  which is an example of a first supporting member and a one-end supporting member, a rear frame  650  which is an example of a second supporting member and an other-end supporting member, a upper frame  660  which is an example of a first longitudinal member and a longitudinal member, and a lower frame  630  which is an example of a second longitudinal member. 
   The front frame  640  rotatably supports one end of the developing roller  510  via the bearing  681 . As shown in  FIG. 8 , the front frame  640  has a bearing hole  641 , a supporting-shaft hole  642  which is an example of a shaft hole, a protrusion  643 , and a screw hole  644 . 
   The bearing hole  641  mates with the bearing  681 . The supporting-shaft hole  642  mates with the gear-supporting shaft  670  that supports the idler gear  511 . The protrusion  643  mates with a positioning hole  631  of the lower frame  630 . The screw hole  644  in which a female screw is formed mates, via the lower frame  630 , with a screw  691  on which a male screw is formed. 
   It should be noted that the front frame  640  is arranged in the lateral direction of the housing  540 . 
   The rear frame  650  rotatably supports the other end of the developing roller  510  via the bearing  682 . As shown in  FIG. 9 , the rear frame  650  has a bearing hole  651 , a hole  652 , a protrusion  653 , and a screw hole  654 . 
   The bearing hole  651  mates with the bearing  682 . The hole  652  is for mating with a projection  662  of the upper frame  660 . The protrusion  653  fits into a positioning hole  633  of the lower frame  630 . The screw hole  654  in which a female screw is formed mates, via the lower frame  630 , with a screw  692  on which a male screw is formed. 
   Further, the gap S (see  FIG. 3 ) described above exists between a side surface F of the rear frame  650  that intersects with the longitudinal direction (see  FIG. 5 ) and an opposition surface of the housing  540  that is in opposition to the side surface F. The gap S is provided for preventing the holder  620  and the housing  540  from interfering with one another when they expand or contract in the longitudinal direction due to a change in temperature. 
   It should be noted that the rear frame  650  is arranged in the lateral direction of the housing  540 . 
   The upper frame  660  supports the upper seal  520 . As shown in  FIG. 10 , the upper frame  660  has a screw hole  661  having a female screw  661   a  formed therein, and a projection  662 . 
   By fitting a screw section  673  of the gear-supporting shaft  670  into the screw hole  661  through the front frame  640 , the upper frame  660  and the front frame  640  are connected as shown in  FIG. 12 . 
   By fitting the projection  662  into the hole  652  of the rear frame  650 , the upper frame  660  and the rear frame  650  are connected as shown in  FIG. 6 . Therefore, the upper frame  660  and the rear frame  650  are not connected with screws. 
   It should be noted that the upper frame  660  is arranged in the longitudinal direction of the housing  540 . 
   The lower frame  630  supports the restriction blade  560 . That is, the lower frame  630  also functions as a blade-supporting member for supporting the restriction blade  560 . As shown in  FIG. 7 , the lower frame  630  has the positioning holes  631  and  633 . 
   The positioning hole  631  mates with the protrusion  643  and the positioning hole  633  mates with the protrusion  653 . 
   As shown in  FIG. 6 , the lower frame  630  and the front frame  640  are connected by means of a screw  691 . Also, as shown in  FIG. 6 , the lower frame  630  and the rear frame  650  are connected by means of a screw  692 . 
   It should be noted that the lower frame  630  is arranged in the longitudinal direction of the housing  540 . 
   &lt;Configuration of Gear-supporting Shaft  670 &gt; 
   Further, as shown in  FIG. 11 , the gear-supporting shaft  670  has a first shaft section  671 , a second shaft section  672 , and a screw section  673 . 
   The first shaft section  671  rotatably supports the idler gear  511 . The second shaft section  672  mates with the supporting-shaft hole  642  of the front frame  640 . It should be noted that the diameter D 2  of the second shaft section  672  is smaller than the diameter D 1  of the first shaft section  671 . 
   A male screw  673   a  is formed on the screw section  673 . The male screw  673   a  mates, via the front frame  640 , with a female screw  661   a  formed in the screw hole  661  as shown in  FIG. 12 . The winding direction of the thread of the male screw  673   a  is arranged in such a direction that the front frame  640  and the upper frame  660  become tightened together when the gear-supporting shaft  670  is turned in the rotating direction of the idler gear  511 . It should be noted that the outer diameter D 3  of the screw section  673  is smaller than the diameter D 2  of the second shaft section  672 . 
   &lt;Procedure of assembling the holder  620 &gt; 
   Next, the procedure according to which the holder  620  is assembled is described with reference to  FIG. 13 .  FIG. 13  is a schematic diagram for describing the procedure according to which the holder  620  is assembled. 
   First, the four members that structure the holder  620 , that is, the lower frame  630 , the front frame  640 , the rear frame  650 , and the upper frame  660 , are prepared. 
   Then, the lower frame  630 , the front frame  640 , the rear frame  650 , and the upper frame  660  are connected together while adjusting the state of connection between the lower frame  630 , the front frame  640 , the rear frame  650 , and the upper frame  660  such that the holder  620  becomes a predetermined size. More specifically, the following procedures are carried out. 
   First, both the front frame  640  and the rear frame  650  are connected to the lower frame  630  while adjusting the state of connection of the front frame  640  and the rear frame  650  with respect to the lower frame  630 . 
   For example, the attachment position, in the longitudinal direction, of the front frame  640  and the rear frame  650  with respect to the lower frame  630  is adjusted by adjusting the mating position, in the longitudinal direction, of the protrusion  643  of the front frame  640  (see  FIG. 8 ) and the positioning hole  631  of the lower frame  630  (see  FIG. 7 ), and the mating position, in the longitudinal direction, of the protrusion  653  of the rear frame  650  (see  FIG. 9 ) and the positioning hole  633  of the lower frame  630  (see  FIG. 7 ). In this way, it is possible to adjust the length of the holder  620  in the longitudinal direction to a predetermined length L. 
   Further, the height of the front frame  640  and the rear frame  650  with respect to the lower frame  630  is arranged by providing members  950  and  960  respectively between the rear frame  650  and the lower frame  630 , and the front frame  640  and the lower frame  630 . In this way, it is possible to precisely arrange the position of the developing roller  510  and the restriction blade  560 . 
   Further, the lower frame  630  is connected to both the front frame  640  and the rear frame  650  by fitting, via the lower frame  630 , the screw  691  into the screw hole  644  of the front frame  640  and by fitting, via the lower frame  630 , the screw  692  into the screw hole  654  of the rear frame  650 . 
   Next, the upper frame  660  is connected to both the front frame  640  and the rear frame  650  by fitting the projection  662  (see  FIG. 10 ) into the hole  652  (see  FIG. 9 ) and by fitting, via the front frame  640 , the screw section  673  of the gear-supporting shaft  670  (see  FIG. 11 ) into the screw hole  661  (see  FIG. 10 ) of the upper frame  660  (see  FIG. 12 ). It should be noted that the attachment position of the upper frame  660  with respect to the front frame  640  and the rear frame  650  may be adjusted in order to adjust the positional relationship between the upper seal  520  and the developing roller  510 . 
   In this way, the length of the holder  620  in the longitudinal direction can be adjusted to a predetermined length L by connecting together the four members that structure the holder  620  (i.e., the lower frame  630 , the front frame  640 , the rear frame  650 , and the upper frame  660 ) while adjusting the state of connection among the four members. 
   It should be noted that, when adjusting the state of connection among the four members, a device (also referred to as a “jig” below) that allows the positions of the members to be adjusted appropriately may be used. This makes it possible to adjust the state of connection more precisely and make the size of the holder  620  into the predetermined size. 
   ===(1) Effect of Structuring a Holder by Connecting at Least Three Members=== 
   As described above, the holder  620  (roller-supporting member) is structured by connecting at least three members (the lower frame  630 , the front frame  640 , the rear frame  650 , and the upper frame  660 ). In this way, it is possible to provide more freedom (flexibility) in assembling the holder  620 , and even when there are variations, due to individual differences, in the size of the members forming the holder  620 , it becomes possible to assemble the holder  620  such that those variations in size of the members are absorbed. This is described in detail below. 
   First, a comparative example is described with reference to  FIG. 14  and  FIG. 15A  to  FIG. 15C .  FIG. 14  is a schematic diagram for describing a holder  920  according to a comparative example.  FIG. 15A  is a diagram showing a second frame  940  before a first bent section  940   a  and a second bent section  940   b  are formed therein.  FIG. 15B  is a diagram showing the second frame  940  having the first bent section  940   a  formed therein.  FIG. 15C  is a diagram showing the second frame  940  having the first bent section  940   a  and the second bent section  940   b  formed therein. 
   The holder  920  is made of two members, i.e., a first frame  930  and the second frame  940 . The first frame  930  and the second frame  940  are similar in shape. 
   The second frame  940  is similar in shape to a gathering of the front frame  640 , the rear frame  650 , and the upper frame  660 , and has the first bent section  940   a  and the second bent section  940   b  formed therein. The second frame  940  is formed into a shape having the first bent section  940   a  and the second bent section  940   b  by bending a flat metal plate, such as that shown in  FIG. 15A , twice as shown in  FIG. 15B  and  FIG. 15C . Therefore, due to individual differences, it is difficult to make the length of the second frame  940  in the longitudinal direction and the lateral direction into a predetermined size (into length L and length M, respectively). 
   Incidentally, the coefficient of thermal expansion of the housing  540  (which is made, for example, of resin) and that of the holder  920  (which is made, for example, of metal) are different. Therefore, the amount of expansion/contraction due to a change in temperature is different between the housing  540  and the holder  920 . Therefore, a gap (such as a gap S) is provided for preventing the holder  920  and the housing  540  from interfering with one another when they expand or contract due to a change in temperature. The gap is designed taking into consideration the amount of expansion/contraction due to a change in temperature of the holder  920  and the housing  540 . 
   However, if the second frame  940  is formed larger than the predetermined size, then the housing  540  and the holder  920  may expand/contract due to a change in temperature and interfere with one another. This is because if the second frame  940  is larger than the predetermined size, then the amount of expansion/contraction of the holder  920  and the housing  540  when these expand/contract due to a change in temperature becomes larger than the gap. 
   As described above, if the holder  920  is structured by connecting only two members (i.e., the first frame  930  and the second frame  940 ), then the holder  920  cannot be formed into a desired size, and further the holder  920  and the housing  540  may interfere with one another when they expand or contract due to a change in temperature. 
   On the other hand, when the holder  620  is formed by connecting at least three members (the lower frame  630 , the front frame  640 , the rear frame  650 , and the upper frame  660 ) as shown in  FIG. 6 , then the freedom (flexibility) in assembling the holder  620  is improved, and for example, the state of connection among the members can be adjusted. Therefore, it becomes possible to form the holder  620  into a desired size. Forming the holder  620  into a desired size allows the holder  620  and the housing  540  to be prevented from interfering with one another when they expand or contract due to a change in temperature. 
   ===(1) Other Considerations=== 
   The foregoing embodiment relates to a developing unit (developing device)  51 ,  52 ,  53 , or  54  comprising: a housing  540  (developer containing section) that is for containing a toner T (developer) and that has a predetermined coefficient of thermal expansion; a developing roller  510  for bearing the toner T contained in the housing  540 ; a holder  620  (roller-supporting member) that is for rotatably supporting the developing roller  510  and that has a coefficient of thermal expansion which is different from the coefficient of thermal expansion of the housing  540 ; and a gap for preventing the holder  620  and the housing  540  from interfering with one another when they expand/contract due to a change in temperature. 
   It should be noted that in the foregoing embodiment, the upper frame  660  and the front frame  640  were connected by fitting the screw section  673  of the gear-supporting shaft  670  into the screw hole  661  through the front frame  640  (see  FIG. 12 ). This, however, is not a limitation. 
   For example, the upper frame  660  and the front frame  640  can be connected by fitting a screw, other than the screw section  673  of the gear-supporting shaft  670 , into a screw hole through the front frame  640 . 
   Further, in the foregoing embodiment, the holder  620  was mounted to the housing  540  such that a longitudinal direction of the holder  620  is arranged in a longitudinal direction of the housing  540  (see  FIG. 3 ); and the developing device had a gap S (see  FIG. 3 ) for preventing the holder  620  and the housing  540  from interfering with one another when the holder  620  and the housing  540  expand/contract in their longitudinal direction due to a change in temperature. This, however, is not a limitation. 
   For example, the gap may be provided for preventing the holder  620  and the housing  540  from interfering with one another when they expand/contract in their lateral direction due to a change in temperature. 
   However, the length of the holder  620  and the housing  540  is longer in their longitudinal direction than in their lateral direction. Therefore, the amount of expansion/contraction due to a change in temperature becomes larger in the longitudinal direction than in the lateral direction. In view of this, developing devices are often provide with a gap for preventing the holder  620  and the housing  540  from interfering with one another when they expand/contract in their longitudinal direction due to a change in temperature. In this way, when the holder  620  is structured by connecting at least three members (the lower frame  630 , the front frame  640 , the rear frame  650 , and the upper frame  660 ), it becomes possible to set the length of the holder  620  in the longitudinal direction to a desired size such that the housing  540  and the holder  620  do not interfere with one another even when they expand/contract in the longitudinal direction due to a change in temperature. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, as shown in  FIG. 6 , the holder  620  was structured by connecting together the following four members: a front frame  640  (first supporting member) that is arranged in a lateral direction intersecting with the longitudinal direction of the holder  620  and that is for supporting one end of the developing roller  510 , a rear frame  650  (second supporting member) that is arranged in the lateral direction and that is for supporting the other end of the developing roller  510 , and a upper frame  660  (first longitudinal member) and a lower frame  630  (second longitudinal member) that are each connected to both the front frame  640  and the rear frame  650  and that are arranged in the longitudinal direction. This, however, is not a limitation. 
   For example, the holder  620  may be made of three members, as shown in  FIG. 16 . That is, the holder  620  may be structured by connecting a lower frame  630 , a rear frame  650 , and a second front frame  840 . It should be noted that  FIG. 16  is a schematic diagram showing another embodiment of the holder  620 . 
   However, when the holder  620  is structured by connecting four members (the lower frame  630 , the front frame  640 , the rear frame  650 , and the upper frame  660 ), it is possible to increase the freedom (flexibility) in assembling the holder  620  and structure the holder  620  such that the length in the longitudinal direction of the holder  620  is set to a desired size, compared to a case where the holder is formed by connecting three members (the lower frame  630 , the rear frame  650 , and the second front frame  840 ). The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the developing device had a restriction blade  560  for restricting a thickness of a layer of the toner T borne by the developing roller  510 ; and the lower frame  630  was a blade-supporting member (see  FIG. 7 ) for supporting the restriction blade  560 . This, however, is not a limitation. 
   For example, the lower frame  630  does not have to support the restriction blade  560 . 
   However, it is necessary to control the position between the developing roller  510  and the restriction blade  560  with satisfactory precision in order to restrict the thickness of the layer of the toner T borne on the developing roller  510 . If the holder  620  is made of four members (the lower frame  630 , the front frame  640 , the rear frame  650 , and the upper frame  660 ), then it becomes possible to structure the holder  620  such that the positioning between the developing roller  510  and the restriction blade  560  is performed with high precision. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, a developing-roller gear  512  (roller gear) for rotating the developing roller  510  with a drive force transmitted from a motor  501  (drive source) was provided on the one end of the developing roller  510 ; and the gap S (see  FIG. 3 ) existed between a side surface F of the rear frame  650  that intersects with the longitudinal direction, and an opposition surface of the housing  540  that is in opposition to the side surface F. This, however, is not a limitation. 
   For example, the gap may be between a side surface of the front frame  640  that intersects with the longitudinal direction and an opposition surface of the housing  540  that is in opposition to that side surface. 
   However, it is possible to prevent the driving section from being affected by providing the gap S, which is between the holder  620  and the housing  540 , between the side surface F of the rear frame  650  and the opposition surface of the housing  540 , that is, on the opposite side from the driving section where the developing-roller gear  512  is located. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the lower frame  630  and the front frame  640  were connected with a screw, the lower frame  630  and the rear frame  650  were connected with a screw, and the front frame  640  and the upper frame  660  were connected with a screw (see  FIG. 5  and  FIG. 12 ); and the rear frame  650  and upper frame  660  were not connected with a screw. This, however, is not a limitation. 
   For example, the rear frame  650  and the upper frame  660  may also be connected with screws. 
   However, since the lower frame  630  and the front frame  640 , the lower frame  630  and the rear frame  650 , and the front frame  640  and the upper frame  660  are connected with screws, respectively, even when the rear frame  650  and upper frame  660  are not connected with a screw, the function of the holder  620 , which is to support the developing roller  510 , can be achieved. Further, by not connecting the rear frame  650  and upper frame  660  with a screw, the time required for assembling the holder  620  can be shortened. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, a projection  662  was provided at an end of the upper frame  660  that is connected to the rear frame  650 ; a hole  652  was provided in the rear frame  650 ; and the projection  662  was fitted into the hole  652  (see  FIG. 6 ). This, however, is not a limitation. 
   For example, the upper frame  660  does not have to be provided with the projection  662  and the rear frame  650  does not have to be provided with the hole  652 . 
   However, when the upper frame  660  is provided with the projection  662  and the rear frame  650  is provided with the hole  652 , it becomes possible to set the length in the longitudinal direction of the holder  620  to a desired size, even when there are variations in size in the longitudinal direction of the upper frame  660  due to individual differences. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the housing  540  was made of resin (such as ABS (acrylonitrile butadiene styrene) resin or PS (polystyrene) resin), and the holder  620  was made of metal (such as aluminum alloy, SECC, and SPCC+Ni (nickel) plating). This, however, is not a limitation. 
   For example, the housing  540  and the holder  620  may both be made of resin. 
   However, the housing  540  is often made of resin to achieve weight reduction, and the holder  620  is often made of metal to hold the developing roller  510  reliably. The difference in the coefficient of thermal expansion between resin and metal is larger than the difference in the coefficient of thermal expansion between two resin components. Therefore, the resin-made housing  540  and the metal-made holder  620  are more likely to interfere with one another when they expand/contract due to a change in temperature. Thus, the effect of the present embodiment, i.e., the effect of allowing the holder  620  to be structured in a desired size, is achieved more advantageously. The foregoing embodiment is therefore more preferable in this sense. 
   &lt;&lt;&lt;Second Embodiment&gt;&gt;&gt; 
   Next, a developing unit according to a second embodiment will be described, focusing on only the features that are different from those of the first embodiment. It should be noted that the configuration of the overall image forming apparatus and the configuration of the control unit are the same for the present second embodiment, the first embodiment described above, and third embodiment described later on. Further, the descriptions on the “Overview of developing unit”, “Internal configuration of developing unit”, “Configuration of driving section”, “Operation of developing unit”, “Overview of holder unit”, “Configuration of the holder unit  610 ”, “Configuration of the holder  620 ”, and “Configuration of gear-supporting shaft  670 ” that were given in the first embodiment apply to the second embodiment as well, and therefore, repeated description thereof is omitted. 
   It should be noted that the holder unit  610  of the present second embodiment includes the holder  620 , which is an example of a roller-supporting member, that rotatably supports the developing roller  510 , the upper seal  520 , the restriction blade  560 , and the end seals  527 , and in addition to these, a gear-supporting shaft  670  that is fixed to the holder  620 . 
   &lt;Periphery of Gear-supporting Shaft  670 &gt; 
   As described above, the second shaft section  672  of the gear-supporting shaft  670  is fitted to the supporting-shaft hole  642  of the front frame  640 . Further, the outer diameter D 2  of the second shaft section  672  is approximately equal to the inner diameter of the supporting-shaft hole  642 . Therefore, when the second shaft section  672  is fitted into the supporting-shaft hole  642 , the gear-supporting shaft  670  is supported at a predetermined position with respect to the front frame  640 . 
   Further, the developing roller  510  is supported by the front frame  640  through the bearing  681 . The outer diameter of the developing roller  510  is approximately equal to the inner diameter d 1  of the bearing  681 , and the outer diameter d 2  of the bearing  681  is approximately equal to the inner diameter of the bearing hole  641 . Therefore, the developing roller  510  is supported at a predetermined position with respect to the front frame  640 . 
   Since the developing roller and the gear-supporting shaft  670  are supported at a predetermined position with respect to the front frame  640  as described above, it is possible to set the distance between the developing-roller gear  512  supported by the developing roller  510  and the idler gear  511  supported by the gear-supporting shaft  670  to a predetermined distance A (see  FIG. 18 ). 
   It should be noted that since the gear-supporting shaft  670  is supported at a predetermined position with respect to the front frame  640  as described above, the upper frame  660  can be connected to the front frame  640  at a predetermined position when the screw section  673  is fitted into the screw hole  661 . 
   ===(2) Function of Gear-supporting Shaft  670 === 
   As described above, the holder  620  (the roller-supporting member) is structured by connecting at least two members (the front frame  640 , the rear frame  650 , the upper frame  660 , and the lower frame  630 ), and the two members (the front frame  640  and the upper frame  660 ) that structure the holder  620  are connected with the screw section  673  provided on the gear-supporting shaft  670 . In this way, the gear-supporting shaft  670  functions also as a screw, and thus, the ease of assembly of the holder  620  can be improved. This is described in detail below. 
   Since the developing roller  510  is supported at both ends (i.e., at one end and the other end), the holder  620  is structured by connecting at least two members (the front frame  640 , the rear frame  650 , the upper frame  660 , and the lower frame  630 ). 
   Further, the gear-supporting shaft  670  that supports the idler gear  511  for transmitting the drive force from the drive motor  501  to the developing-roller gear  512  is fixed to the holder  620 . 
   For this reason, there has been a need to carry out two different tasks (i.e., the task of connecting the two members with a screw and the task of fixing the gear-supporting shaft  670  to the member) when assembling the holder  620 . 
   On the other hand, by providing a screw section  673  on the gear-supporting shaft  670  as in the present embodiment, the two members (the front frame  640  and the upper frame  660 ) are connected at the same time the gear-supporting shaft  670  is fixed to the holder  620 . In other words, connection of the front frame  640  and the upper frame  660  and fixing of the gear-supporting shaft  670  to the holder  620  are carried out through a single task. Therefore, it is possible to shorten the time necessary for assembling the holder  620 . 
   As described above, by connecting the front frame  640  and the upper frame  660  using the screw section  673  of the gear-supporting shaft  670 , it is possible to shorten the amount of time necessary for assembling the holder  620 , and thus improve the ease of assembly of the holder  620 . 
   ===(2) Other Considerations=== 
   The foregoing embodiment relates to a developing unit (developing device)  51 ,  52 ,  53 , or  54  comprising: a developing roller  510  for bearing a toner T (developer); a holder  620  (roller-supporting member) for rotatably supporting the developing roller  510 ; a developing-roller gear  512  (roller gear) that is provided at one end of the developing roller  510  and that is for rotating the developing roller  510 ; an idler gear  511  (intermediate gear) for transmitting a drive force from a drive motor  501  (drive source) to the developing-roller gear  512 ; and a gear-supporting shaft  670  for rotatably supporting the idler gear  511 . 
   It should be noted that in the foregoing embodiment, the upper frame  660  and the rear frame  650  were connected by fitting the projection  662  of the upper frame  660  into the hole  652  of the rear frame  650  (see  FIG. 6 ). This, however, is not a limitation. 
   For example, the upper frame  660  and the rear frame  650  may be connected with screws. However, connecting the upper frame  660  and the rear frame  650  by fitting the projection  662  into the hole  652  renders the screws for connecting the upper frame  660  and the rear frame  650  unnecessary, and thus, the ease in assembly of the holder  620  can be further improved. 
   Further, in the foregoing embodiment, the front frame  640  and the lower frame  630  were connected with a screw  691 . This, however, is not a limitation. 
   For example, the front frame  640  and the lower frame  630  may be connected using a screw section provided on a gear-supporting shaft that supports another gear. In this case, since the screw  691  becomes unnecessary, the ease in assembly of the holder  620  can be further improved. 
   Further, in the foregoing embodiment, one of the at least two members (the front frame  640  and the upper frame  660 ) forming the holder  620  was a front frame  640  (one-end supporting member) for rotatably supporting, through a bearing  681 , the one end of the developing roller  510 ; and as shown in  FIG. 8 , the front frame  640  was provided with a supporting-shaft hole  642  (shaft hole) for mating with the gear-supporting shaft  670  and a bearing hole  641  for mating with the bearing  681 . This, however, is not a limitation. 
   For example, the gear-supporting shaft  670  does not have to fit into the supporting-shaft hole  642 . Further, the bearing  681  does not have to fit into the bearing hole  641 . 
   However, when the gear-supporting shaft  670  is fitted into the supporting-shaft hole  642  and the bearing  681  is fitted into the bearing hole  641  as described above, the positions where the gear-supporting shaft  670  and the bearing  681  are mated with the front frame  640  can be kept constant. In this way, the distance between the idler gear  511  supported by the gear-supporting shaft  670  and the developing-roller gear  512  supported by the developing roller  510  that mates with the bearing  681  can be set to a constant value. Therefore, it becomes possible to control the distance between the idler gear  511  and the developing-roller gear  512  with high precision. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the idler gear  511  meshed with the developing-roller gear  512 . This, however, is not a limitation. 
   For example, another gear may be provided between the idler gear  511  and the developing-roller gear  512 . 
   However, when the idler gear  511  meshes with the developing-roller gear  512  (see  FIG. 18 ), it is possible to transmit the drive force from the idler gear  511  to the developing-roller gear  512  properly when the distance between the idler gear  511  and the developing-roller gear  512  is controlled with higher precision. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the two members were: the front frame  640 , and an upper frame  660  (longitudinal member) that is arranged in a longitudinal direction of the developing roller  510  and that is connected to the front frame  640 ; the gear-supportingshaft  670  was provided with: a first shaft section  671  for rotatably supporting the idler gear  511 , a second shaft section  672  whose diameter is smaller than a diameter of the first shaft section  671 , and the screw section  673  whose diameter is smaller than the diameter of the second shaft section  672  and on which a male screw  673   a  is formed; the upper frame  660  had a screw hole  661  having a female screw  661   a  formed therein; and the front frame  640  and the upper frame  660  were connected by fitting the male screw  673   a  into the female screw  661   a  in a state where the second shaft section  672  is fitted into the supporting-shaft hole  642  (see  FIG. 18 ). This, however, is not a limitation. 
   For example, as shown in  FIG. 19 , the gear-supporting section  670  may be provided with the first shaft section  671  and a screw section  676  having a female screw formed therein; the upper frame  660  may have a hole  668  that does not have a female screw; and the front frame  640  and the upper frame  660  may be connected by fitting the male screw formed on a screw  695  into the female screw formed in the screw section  676  in a state where the screw section  676  is fitted into the supporting-shaft hole  642  and the hole  668 . It should be noted that  FIG. 19  is a diagram for describing another example. 
   However, by connecting the front frame  640  and the upper frame  660  by fitting the male screw  673   a  into the female screw  661   a  in a state where the second shaft section  672  is fitted into the supporting-shaft hole  642 , it becomes possible to reliably connect the front frame  640  and the upper frame  660  with a simple structure. 
   Further, in the foregoing embodiment, the idler gear  511  rotated in a predetermined direction (the direction shown in  FIG. 4 ); and a winding direction of a thread of the male screw  673   a  was arranged in such a direction that the front frame  640  and the upper frame  660  are tightened together when the gear-supporting shaft  670  is rotated in the rotating direction of the idler gear  511 . This, however, is not a limitation. 
   For example, the winding direction of the thread of the male screw  673   a  may be arranged in such a direction that the front frame  640  and the upper frame  660  are loosened when the gear-supporting shaft  670  is rotated in the rotating direction of the idler gear  511 . 
   However, when the winding direction of the thread of the male screw  673   a  is arranged in such a direction that the front frame  640  and the upper frame  660  are tightened together, it becomes possible to prevent the male screw  673   a  from loosening from the female screw  661   a . The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the developing device had: a housing  540  (developer containing section) for containing a toner T, and a upper seal  520  that abuts against the developing roller  510  and that is for preventing the toner T from spilling from between the developing roller  510  and the housing  540 ; and the upper seal  520  was supported by the upper frame  660 . This, however, is not a limitation. 
   For example, the upper seal  520  may be supported by the housing  540 . 
   However, by fitting the male screw  673   a  of the gear-supporting shaft  670 , which is supported at a predetermined position with respect to the front frame  640  through mating of the second shaft section  672  and the supporting-shaft hole  642 , into the female screw  661   a  of the upper frame  660 , it is possible to control the attachment position of the upper frame  660  with respect to the front frame  640  with satisfactory precision. In this case, it is possible to properly control the abutment of the upper seal  520  against the developing roller  510  when the upper seal  520  is supported by the upper frame  660 , and therefore effectively prevent the toner T from spilling from between the developing roller  510  and the housing  540 . The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the holder  620  was structured by connecting together the following four members: the front frame  640 , a rear frame  650  (other-end supporting member) for rotatably supporting, through a bearing  682 , an other end of the developing roller  510 , and the upper frame  660  and a lower frame  630  (second longitudinal member) that are each connected to both the front frame  640  and the rear frame  650  and that are arranged in the longitudinal direction. This, however, is not a limitation. 
   For example, the holder  620  may be structured by connecting two or three members. 
   &lt;&lt;&lt;Third Embodiment&gt;&gt;&gt; 
   ===(3) Overview of Developing Unit=== 
   Next, using  FIG. 20  and  FIG. 21 , an example of a configuration of a developing unit according to a third embodiment will be described. It should be noted that the configuration of the overall image forming apparatus and the configuration of the control unit are the same for the present third embodiment and the first and second embodiments described above.  FIG. 20  is a conceptual diagram of a developing unit according to a third embodiment.  FIG. 21  is a section view showing main structural components of the developing unit  3054  according to the third embodiment. It should be noted that the section view shown in  FIG. 21  is a cross section of the developing unit  3054  bisected by a plane perpendicular to the longitudinal direction shown in  FIG. 20 . Further, in  FIG. 21 , the arrow indicates the vertical direction as in  FIG. 1 , and, for example, the central axis of the developing roller  3510  is located below the central axis of the photoconductor  20 . Further, in  FIG. 21 , the yellow developing unit  3054  is shown to be in a state in which it is positioned at the developing position opposing the photoconductor  20 . 
   To the rotating body  50 , it is possible to attach: the black developing unit  51  containing black (K) toner; the magenta developing unit  52  containing magenta (M) toner; the cyan developing unit  53  containing cyan (C) toner; and the yellow developing unit  3054  ( 54 ) containing yellow (Y) toner. Since the configuration of the developing units of this embodiment is the same, explanation will be made only about the yellow developing unit  3054  below. 
   &lt;Configuration of Developing Unit&gt; 
   The yellow developing unit  3054  has the developing roller  3510  which is an example of a developer bearing roller, an upper seal  3520  which is an example of a sealing member, a housing  3540 , a toner supplying roller  3550 , a restriction blade  3560  which is an example of a developer charging member, and so forth. 
   The developing roller  3510  bears toner T and delivers it to the developing position opposing the photoconductor  20 . The developing roller  3510  is made of metal and, for example, it is manufactured from aluminum alloy such as aluminum alloy  5056  or aluminum alloy  6063 , or iron alloy such as STKM, and the roller  3510  is plated with, for example, nickel plating or chromium plating, as necessary. 
   The developing roller  3510  has a shaft section  3510   a  and a large-diameter section  3510   b . The shaft section  3510   a  is supported, through bearings  3680  and  3682 , by a first side metal plate  3640  and a second side metal plate  3650  of a holder  3620  described further below, and thereby the developing roller  3510  is supported rotatably. As shown in  FIG. 21 , the developing roller  3510  rotates in the opposite direction (counterclockwise in  FIG. 21 ) to the rotating direction of the photoconductor  20  (clockwise in  FIG. 21 ). The central axis of the roller  3510  is located below the central axis of the photoconductor  20 . 
   Further, as shown in  FIG. 21 , in the state where the yellow developing unit  3054  opposes the photoconductor  20 , there is a gap between the developing roller  3510  and the photoconductor  20 . That is, the yellow developing unit  3054  develops the latent image formed on the photoconductor  20  in a non-contacting state. It should be noted that an alternating field is generated between the developing roller  3510  and the photoconductor  20  upon development of the latent image formed on the photoconductor  20 . 
   The housing  3540  is manufactured by welding together a plurality of integrally-molded housing sections, that is, an upper housing section  3542  and a lower housing section  3544 . In the housing  3540  is formed a toner containing section  3530  for containing the toner T. The toner containing section  3530  is divided into two toner containing sections, namely, the first toner containing section  3530   a  and the second toner containing section  3530   b , by a partitioning wall  3545  that is for partitioning the toner T and that protrudes inwards (in the up/down direction of  FIG. 21 ) from the inner wall. It should be noted that an opening  3572  is located at the lower section of the housing  3540 , and the developing roller  3510  is arranged with respect to the opening  3572  such that a portion of the roller  3510  is exposed from the opening. 
   The toner containing sections  3530  may be provided with a stirring member for stirring the toner T. In the present embodiment, however, no stirring member is provided in the toner containing sections  3530  because each of the developing units (i.e., the black developing unit  51 , the magenta developing unit  52 , the cyan developing unit  53 , and the yellow developing unit  3054  ( 54 )) is rotated with the rotation of the rotating body  50  and the toner T in each developing unit is thereby stirred. 
   The toner supplying roller  3550  is provided in the first toner containing section  3530   a  described above and supplies the toner T contained in the first toner containing section  3530   a  to the developing roller  3510 . The toner supplying roller  3550  is made of, for example, polyurethane foam, and is made to abut against the developing roller  3510  in an elastically deformed state. The toner supplying roller  3550  is arranged at a lower section of the toner containing section  3530 . The toner T contained in the toner containing sections  3530  is supplied to the developing roller  3510  by the toner supplying roller  3550  at the lower section of the toner containing section  3530 . 
   The toner supplying roller  3550  is rotatable about its central axis. The central axis of the toner supplying roller  3550  is situated below the central axis of rotation of the developing roller  3510 . Further, the toner supplying roller  3550  rotates in the opposite direction (clockwise in  FIG. 21 ) to the rotating direction of the developing roller  3510  (counterclockwise in  FIG. 21 ). It should be noted that the toner supplying roller  3550  has the function of supplying the toner T contained in the toner containing section  3530  to the developing roller  3510  as well as the function of stripping off, from the developing roller  3510 , the toner T remaining on the developing roller  3510  after development. 
   The upper seal  3520  abuts against the developing roller  3510  along the axial direction thereof, and prevents the toner T in the yellow developing unit  3054  from spilling out therefrom, and also collects the toner T, which is on the developing roller  3510  that has passed the developing position, into the developing device without scraping it off. The upper seal  3520  is a seal made of, for example, polyethylene film. The upper seal  3520  is supported by an upper-seal-supporting metal plate  3660  of the holder  3620  described below, and is arranged such that the longitudinal direction of the upper seal  3520  is in the axial direction of the developing roller  3510 . 
   A seal-urging member  3524  made of, for example, Moltoprene is provided on one side of the upper seal  3520  opposite from the side of the developing roller  3510 . The upper seal  3520  is pressed against the developing roller  3510  by the elastic force of the seal-urging member  3524 . Further, the abutting position at which the upper seal  3520  abuts against the developing roller  3510  is located above the central axis of the developing roller  3510 . 
   The restriction blade  3560  abuts against the developing roller  3510  along the axial direction thereof, and gives an electric charge to the toner T borne by the developing roller  3510  as well as restricts the thickness of the layer of the toner T borne by the developing roller  3510 . The restriction blade  3560  includes a rubber section  3561 , which is an example of an abutting section, and a rubber-supporting section  3562 , which is an example of an abutment-supporting section. The rubber section  3561  is made of, for example, silicone rubber or urethane rubber. The rubber-supporting section  3562  is a thin plate that is made of, for example, phosphor bronze or stainless steel, and that has a spring-like characteristic. The rubber section  3561  is supported by the rubber-supporting section  3562 . The rubber-supporting section  3562  is supported at one end, in the lateral direction, by a blade-supporting metal plate  3630  of the holder  3620 . 
   Further, a housing seal  3570  made of, for example, Moltoprene is provided on one side of the restriction blade  3560  opposite from the side of the developing roller  3510 . The rubber section  3561  is pressed against the developing roller  3510  by the elastic force caused by the flexure of the rubber-supporting section  3562 . Further, the housing seal  3570  prevents the toner T from entering in between the rubber-supporting section  3562  and the housing  3540 , stabilizes the elastic force caused by the flexure of the rubber-supporting section  3562 , and also, applies force to the rubber section  3561  from the back thereof towards the developing roller  3510  to press the rubber section  3561  against the developing roller  3510 . In this way, the housing seal  3570  makes the rubber section  3561  abut against the developing roller  3510  more evenly. 
   The end of the restricting blade  3560  opposite from the end that is being supported by the blade-supporting metal plate  3630 , i.e., the tip end of the restriction blade  3560 , is not placed in contact with the developing roller  3510 ; rather, a section at a predetermined distance from the tip end contacts, with some breadth, the developing roller  3510 . That is, the restriction blade  3560  does not abut against the developing roller  3510  at its edge, but abuts against the roller  3510  near its central portion. Further, the restriction blade  3560  is arranged so that its tip end faces towards the upstream side of the rotating direction of the developing roller  3510 , and thus, makes a so-called counter-abutment with respect to the roller  3510 . It should be noted that the abutting position at which the restriction blade  3560  abuts against the developing roller  3510  is below the central axis of the developing roller  3510  and is also below the central axis of the toner supplying roller  3550 . 
   &lt;Operation of Developing Unit&gt; 
   In the yellow developing unit  3054  structured as above, the toner supplying roller  3550  supplies the toner T contained in the toner containing section  3530  to the developing roller  3510 . With the rotation of the developing roller  3510 , the toner T, which has been supplied to the developing roller  3510 , reaches the abutting position of the restriction blade  3560 ; then, as the toner T passes the abutting position, the toner is electrically charged and its layer thickness is restricted. 
   With further rotation of the developing roller  3510 , the toner T on the developing roller  3510  whose layer thickness has been restricted reaches the developing position opposing the photoconductor  20 ; then, under the alternating field, the toner T is used at the developing position for developing the latent image formed on the photoconductor  20 . 
   With further rotation of the developing roller  3510 , the toner T on the developing roller  3510 , which has passed the developing position, passes the upper seal  3520  and is collected into the developing unit by the upper seal  3520  without being scraped off. Then, the toner T that still remains on the developing roller  3510  can be stripped off by the toner supplying roller  3550 . 
   ===(3) Configuration of Holder Unit etc.=== 
   Next, the configuration of the holder unit  3610  according to the present third embodiment is described with reference to  FIG. 22 ,  FIG. 23 ,  FIG. 24A ,  FIG. 24B ,  FIG. 24C ,  FIG. 24D ,  FIG. 25 , and  FIG. 26 .  FIG. 22  is a perspective view of a holder unit  3610 .  FIG. 23  is a perspective view of a holder  3620 .  FIG. 24A  shows the state of connection between the blade-supporting metal plate  3630  and the second side metal plate  3650 ,  FIG. 24B  shows the state of connection between the blade-supporting metal plate  3630  and the first side metal plate  3640 ,  FIG. 24C  shows a state of connection between the upper-seal-supporting metal plate  3660  and the second side metal plate  3650 , and  FIG. 24D  shows the state of connection between the upper-seal-supporting metal plate  3660  and the first side metal plate  3640 .  FIG. 25  is a perspective view of the blade-supporting metal plate  3630 .  FIG. 26  is a perspective view showing a state in which the restriction blade  3560  is supported by the blade-supporting metal plate  3630 . 
   As shown in  FIG. 22 , the holder unit  3610  is structured of, for example, the developing roller  3510 , the upper seal  3520 , the restriction blade  3560 , and a holder  3620  that supports them. As shown in  FIG. 23 , the holder  3620  is structured by connecting a first side metal plate  3640  which is made of metal and is an example of a one-end supporting member, a second side metal plate  3650  which is made of metal and is an example of an other-end supporting member, a blade-supporting metal plate  3630  which is made of metal and is an example of a charge-supporting member, and a upper-seal-supporting metal plate  3660  which is made of metal and is an example of a seal-supporting member. It should be noted that the first side metal plate  3640  and the second side metal plate  3650  are an example of a bearing-roller-supporting member. 
   The longitudinal direction of the first side metal plate  3640  is arranged in the lateral direction of the holder  3620  (i.e., the direction intersecting with the axial direction of the developing roller  3510 ), and rotatably supports one end, in the axial direction, of the developing roller  3510 . The first side metal plate  3640  has a bearing hole  3642 , which is an example of a roller-supporting hole, and a supporting-shaft hole (not shown) into which the supporting shaft  3670  for supporting the gear (not shown) is fitted. As shown in  FIG. 22 , the shaft section  3510   a  on the side of one end of the developing roller  3510  is supported, through the bearing  3680 , by the bearing hole  3642  in a state where the bearing hole  3642  and the bearing  3680  mate with one another. 
   The longitudinal direction of the second side metal plate  3650  is arranged in the lateral direction of the holder  3620  (i.e., the direction intersecting with the axial direction of the developing roller  3510 ), and rotatably supports the other end, in the axial direction, of the developing roller  3510 . The second side metal plate  3650  has a bearing hole  3652 , which is an example of a roller-supporting hole, and a hole  3654 . As shown in  FIG. 22 , the shaft section  3510   a  on the side of the other end of the developing roller  3510  is supported, through the bearing  3682 , by the bearing hole  3652  in a state where the bearing hole  3652  and the bearing  3682  mate with one another. The hole  3654  mates with a projection  3664  provided on the upper-seal-supporting metal plate  3660 . 
   The longitudinal direction of the blade-supporting metal plate  3630  is arranged in the longitudinal direction of the holder  3620  (i.e., the axial direction of the developing roller  3510 ), and supports the restriction blade  3560 . As shown in  FIG. 25 , the blade-supporting metal plate  3630  has a blade-supporting section  3631 , and a first bent section  3632  and a second bent section  3633  that have been bent at both ends in the longitudinal direction (which are an example of sections that have been bent at both ends of a charge-supporting member). 
   The blade-supporting section  3631  supports the rubber-supporting section  3562  of the restriction blade  3560 . As shown in  FIG. 26 , the blade-supporting section  3631  and one end, in the lateral direction, of the rubber-supporting section  3562  are welded together through laser spot welding (the dots indicated by W in  FIG. 26 ), and in this way, the restriction blade  3560  is supported by the blade-supporting metal plate  3630 . 
   As shown in  FIG. 25 , a bent surface  3632   a  is formed in the first bent section  3632 . As shown in  FIG. 24B , the bent surface  3632   a  and the first side metal plate  3640  are welded through laser spot welding (the dots indicated by W in  FIG. 24B ) in a state where the bent surface  3632   a  and the first side metal plate  3640  are in contact with one another, and in this way, the blade-supporting metal plate  3630  and the first side metal plate  3640  are connected. 
   As shown in  FIG. 25 , a bent surface  3633   a  is formed in the second bent section  3633 . As shown in  FIG. 24A , the bent surface  3633   a  and the second side metal plate  3650  are welded through laser spot welding (the dots indicated by W in  FIG. 24A ) in a state where the bent surface  3633   a  and the second side metal plate  3650  are in contact with one another, and in this way, the blade-supporting metal plate  3630  and the second side metal plate  3650  are connected. 
   The longitudinal direction of the upper-seal-supporting metal plate  3660  is arranged in the longitudinal direction of the holder  3620  (i.e., the axial direction of the developing roller  3510 ), and supports the upper seal  3520 . The upper-seal-supporting metal plate  3660  has an upper-seal supporting section  3661 , a first bent section  3662  formed by bending one end in the longitudinal direction of the metal plate  3660 , and a second bent section  3663  formed by bending the metal plate  3660  along its longitudinal direction. The upper-seal supporting section  3661  supports one end, in the lateral direction, of the upper seal  3520  (see  FIG. 21 ). 
   The first bent section  3662  is provided with a screw hole (not shown) that mates with a male screw (not shown) formed on the supporting shaft  3670 . As shown in  FIG. 24D , the male screw of the supporting shaft  3670  is fitted into the screw hole of the first bent section  3662 , and in this way, the upper-seal-supporting metal plate  3660  and the supporting shaft  3670  are connected. Further, as shown in  FIG. 24D , the circumferential surface of the supporting shaft  3670  and the first side metal plate  3640  are welded through laser spot welding (the dots indicated by W in  FIG. 24D ), and in this way, the supporting shaft  3670  and the first side metal plate  3640  are connected. Thus, the upper-seal-supporting metal plate  3660  and the first side metal plate  3640  are connected via the supporting shaft  3670 . 
   The seal-urging member  3524  (see  FIG. 21 ) is fixed to the second bent section  3663 . Further, a projection  3664  that fits into the hole  3654  is provided on the second bent section  3663  at the other end, in the longitudinal direction, of the upper-seal-supporting metal plate  3660 . As shown in  FIG. 24C , the projection  3664  and the second side metal plate  3650  are welded through laser spot welding (the dots indicated by W in  FIG. 24C ) in a state where the projection  3664  is fitted into the hole  3654 , and in this way, the upper-seal-supporting metal plate  3660  and the second side metal plate  3650  are connected. 
   ===(3) Adjustment of the Attachment Position=== 
   Next, adjustment of the attachment position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  and the second side metal plate  3650  is described with reference to  FIG. 27 .  FIG. 27  is a schematic diagram for describing how the attachment position is adjusted. 
   In order to charge the toner T borne by the developing roller  3510  evenly, it is necessary to arrange the restriction blade  3560  in an appropriate position with respect to the developing roller  3510 . In order to arrange the restriction blade  3560  in an appropriate position with respect to the developing roller  3510 , it is necessary to arrange the blade-supporting metal plate  3630 , which supports the restriction blade  3560 , in the most suitable position with respect to the first side metal plate  3640  and the second side metal plate  3650 , which support the developing roller  3510 . 
   In view of this, the attachment position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  and the second side metal plate  3650  is adjusted by adjusting the distance between the bearing hole  3642  of the first side metal plate  3640  (or the bearing hole  3652  of the second side metal plate  3650 ) and the restriction blade  3560 . 
   More specifically, as shown in  FIG. 27 , the attachment position is adjusted by moving a jig  3800  that supports the blade-supporting metal plate  3630 , on which the restriction blade  3560  is supported, with respect to the first side metal plate  3640  (or the second side metal plate  3650 ) supported at a certain position using a jig etc., such that the distance between the edge  3561   a  of the rubber section  3561  and the center  3642   a  of the bearing hole  3642  of the first side metal plate  3640  (or the center  3652   a  of the bearing hole  3652  of the second side metal plate  3650 ) takes a predetermined value (Lx in the X direction and Ly in the Y direction). 
   ===(3) Method of Assembling the Holder  3620 === 
   Next, the method of assembling the holder  3620  is described with reference to  FIG. 28 .  FIG. 28  is a flowchart showing a method of assembling the holder  3620 . 
   First, the blade-supporting metal plate  3630  is made to support the restriction blade  3560  (step S 202 ). More specifically, as shown in  FIG. 26 , the blade-supporting metal plate  3630  is made to support the restriction blade  3560  by welding one end, in the lateral direction, of the rubber-supporting section  3562  and the blade-supporting section  3631  through laser spot welding (the dots indicated by W in  FIG. 26 ). 
   Next, the attachment position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  and the second side metal plate  3650  is adjusted (step S 204 ). More specifically, as shown in  FIG. 27 , the attachment position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  and the second side metal plate  3650  is adjusted such that the distance between the edge  3561   a  of the rubber section  3561  and the center  3642   a  ( 3652   a ) of the bearing hole  3642  ( 3652 ) takes a predetermined value (Lx in the X direction and Ly in the Y direction). 
   Next, the blade-supporting metal plate  3630  is welded through spot welding to both the first side metal plate  3640  and the second side metal plate  3650  (step S 206 ). More specifically, as shown in  FIG. 24A  and  FIG. 24B , the first bent section  3632  and the first side metal plate  3640 , and also the second bent section  3633  and the second side metal plate  3650 , are welded together through laser spot welding (the dots indicated by W in  FIG. 24A  and  FIG. 24B ) in a state where the first bent section  3632  is in contact with the first side metal plate  3640  and the second bent section  3633  is in contact with the second side metal plate  3650 . 
   Next, the upper-seal-supporting metal plate  3660  is connected to both the first side metal plate  3640  and the second side metal plate  3650  (step S 208 ). More specifically, as shown in  FIG. 24C  and  FIG. 24D , the upper-seal-supporting metal plate  3660  is connected to both the first side metal plate  3640  and the second side metal plate  3650  by welding together the projection  3664  and the second side metal plate  3650 , and also the circumferential surface of the supporting shaft  3670  and the first side metal plate  3640 , through laser spot welding (the dots indicated by W in  FIG. 24C  and  FIG. 24D ) in a state where the projection  3664  is fitted into the hole  3654  and the male screw of the supporting shaft  3670  is fitted into the screw hole of the first bent section  3632 . 
   In this way, it is possible to assemble a holder  3620  in which the blade-supporting metal plate  3630  is arranged in an appropriate position with respect to the first side metal plate  3640  and the second side metal plate  3650 . 
   ===(3) Effect of Welding the Developing-roller-supporting Metal Plate and the Blade-supporting Metal Plate Through Spot Welding=== 
   In the present embodiment, the first side metal plate  3640  and the second side metal plate  3650  (which are the bearing-roller-supporting member) and the blade-supporting metal plate  3630  (which is the charge-supporting member) are welded together through spot welding (the dots indicated by W in  FIG. 24A  and  FIG. 24B ). In this way, it becomes possible to arrange the restriction blade  3560  in an appropriate position with respect to the developing roller  3510 . This is described in detail below. 
   First, a comparative example is described with reference to  FIG. 29 .  FIG. 29  is a diagram for describing a comparative example. In this comparative example, the blade-supporting metal plate  3630  is fastened to both the first side metal plate  3640  and the second side metal plate  3650  with screws  3871 . 
   As shown in  FIG. 29 , when fastening the blade-supporting metal plate  3630  and the first side metal plate  3640  using a screw  3871 , the screw  3871  is turned in the direction indicated in  FIG. 29  using a driver  3850 . In this case, the blade-supporting metal plate  3630  may also turn in the direction indicated in  FIG. 29  due to the turning force for causing the screw  3871  to turn. Therefore, the position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  may deviate from its proper position. Further, also when fastening the blade-supporting metal plate  3630  and the second side metal plate  3650  using a screw  3871 , the position of the blade-supporting metal plate  3630  with respect to the second side metal plate  3650  may deviate from its proper position due to the reason described above. 
   As described above, the position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  and/or the second side metal plate  3650  may deviate from its proper position due to the turning force etc. applied from the driver  3850  to make the screw  3871  turn in the case of fastening the blade-supporting metal plate  3630  and both the first side metal plate  3640  and the second side metal plate  3650  using screws  3871 . If the position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  and/or the second side metal plate  3650  deviates from its proper position, then the position of the restriction blade  3560  with respect to the developing roller  3510  may also deviate. 
   On the other hand, according to the present embodiment, as shown in  FIG. 24A  and  FIG. 24B , the first bent section  3632  of the blade-supporting metal plate  3630  and the first side metal plate  3640 , and also the second bent section  3633  of the blade-supporting metal plate  3630  and the second side metal plate  3650 , are connected through laser spot welding (the dots indicated by W in  FIG. 24A  and  FIG. 24B ) which is one type of spot welding. In this case, no turning force is necessary, and therefore, there is no possibility that the blade-supporting metal plate  3630  may turn. Therefore, it is possible to prevent the position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  and/or the second side metal plate  3650  from deviating from its proper position. In this way, it becomes possible to arrange the restriction blade  3560  in an appropriate position with respect to the developing roller  3510 . 
   ===(3) Other Considerations=== 
   The foregoing embodiment relates to a developing unit (developing device)  51 ,  52 ,  53 , or  3054  comprising: a restriction blade  3560  (developer charging member) for charging a toner T (developer) borne by a developing roller  3510  (developer bearing roller); a first side metal plate  3640  and a second side metal plate  3650  (bearing-roller-supporting members) that are made of metal and that are for rotatably supporting the developing roller  3510 ; and a blade-supporting metal plate  3630  (charge-supporting member) that is made of metal and that is for supporting the restriction blade  3560 . 
   Further, in the foregoing embodiment, laser spot welding was adopted as the spot welding, as shown in  FIG. 24A  and  FIG. 24B . This, however, is not a limitation. For example, spot welding other than laser spot welding may be employed. 
   However, when laser spot welding is adopted, since it is possible to control the intensity of the laser beam and the irradiation time easily and therefore keep unnecessary heat from being applied to the first side metal plate  3640  and the second side metal plate  3650  and the blade-supporting metal plate  3630 , deformation of the first side metal plate  3640  and the second side metal plate  3650  and the blade-supporting metal plate  3630  due to heat can be inhibited. Thus, it becomes possible to prevent the deviation in position of the restriction blade  3560  with respect to the developing roller  3510  more effectively. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, as shown in  FIG. 27 , an attachment position where the blade-supporting metal plate  3630  is attached to the first side metal plate  3640  and the second side metal plate  3650  was adjusted, and after adjusting the attachment position, the blade-supporting metal plate  3630  and the first side metal plate  3640  and the second side metal plate  3650  were welded through laser spot welding. This, however, is not a limitation. 
   However, by welding the blade-supporting metal plate  3630  and the first side metal plate  3640  and the second side metal plate  3650  through laser spot welding after adjusting the attachment position thereof, it is possible to prevent the position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  and the second side metal plate  3650  from deviating after the attachment position has been adjusted, and therefore arrange the restriction blade  3560  in a more appropriate position with respect to the developing roller  3510 . The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the bearing-roller-supporting member included a first side metal plate  3640  (one-end supporting member) for rotatably supporting one end, in an axial direction, of the developing roller  3510 , and a second side metal plate  3650  (other-end supporting member) for rotatably supporting an other end, in the axial direction, of the developing roller  3510 ; the blade-supporting metal plate  3630  was provided such that a longitudinal direction thereof is arranged in the axial direction of the developing roller  3510 ; and as shown in  FIG. 24A  and  FIG. 24B , the blade-supporting metal plate  3630  and both the first side metal plate  3640  and the second side metal plate  3650  were welded through laser spot welding. This, however, is not a limitation. For example, the bearing-roller-supporting member may be a member obtained by forming the first side metal plate  3640 , the second side metal plate  3650 , and the upper-seal-supporting metal plate  3660  into a unit. 
   Further, in the foregoing embodiment, both ends (i.e., the first bent section  3632  and the second bent section  3633 ), in the longitudinal direction, of the blade-supporting metal plate  3630  were bent; and as shown in  FIG. 24A  and  FIG. 24B , the first bent section  3632  and the second bent section  3633  were welded, respectively, through laser spot welding to the first side metal plate  3640  and the second side metal plate  3650  in a state where the first bent section  3632  and the second bent section  3633  are placed in contact, respectively, with the first side metal plate  3640  and the second side metal plate  3650 . This, however, is not a limitation. For example, both ends, in the longitudinal direction, of the blade-supporting metal plate  3630  do not have to be bent, but instead, bent sections may be provided in the first side metal plate  3640  and the second side metal plate  3650 , and these bent sections may be welded to the blade-supporting metal plate  3630  through laser spot welding. 
   However, when the first bent section  3632  and the second bent section  3633  are formed in the blade-supporting metal plate  3630 , and the first bent section  3632  and the first side metal plate  3640 , as well as the second bent section  3633  and the second side metal plate  3650 , are fastened together with a screw, the position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  and the second side metal plate  3650  is more likely to deviate from its proper position due to the turning force etc. for causing the screw to turn. In such a case, the effect of the present invention, i.e., the effect of allowing the restriction blade  3560  to be arranged in an appropriate position with respect to the developing roller  3510 , is achieved more advantageously. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the restriction blade  3560  was provided with a rubber section  3561  (abutting section) that abuts against the developing roller  3510  as shown in  FIG. 21 . This, however, is not a limitation. For example, the restriction blade  3560  does not have to abut against the developing roller  3510 . 
   However, if the rubber section  3561  is provided on the restriction blade  3560 , it is necessary to arrange the abutting section in an appropriate position with respect to the developing roller  3510  to make the electric charge of the toner T on the developing roller  3510  even. In such a case, the effect of the present invention, i.e., the effect of allowing the restriction blade  3560  to be arranged in an appropriate position with respect to the developing roller  3510 , is achieved more advantageously. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the restriction blade  3560  was provided with a rubber-supporting section  3562  (abutment-supporting section) whose one end, in a lateral direction, is supported by the blade-supporting metal plate  3630  and whose other end is for supporting the rubber section  3561 ; and as shown in  FIG. 26 , the rubber-supporting section  3562  and the blade-supporting metal plate  3630  were welded through laser spot welding. This, however, is not a limitation. For example, the rubber-supporting section  3562  may be supported by the blade-supporting metal plate  3630  without being welded through spot welding. 
   However, if the rubber-supporting section  3562  and the blade-supporting metal plate  3630  are welded through laser spot welding, then since the first side metal plate  3640  and the second side metal plate  3650  and the blade-supporting metal plate  3630 , as well as the rubber-supporting section  3562  and the blade-supporting metal plate  3630 , are welded through the same laser spot welding technique, the burden of changing the method for welding can be eliminated, and therefore, it becomes possible to improve the workability during manufacturing. The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the developing device had an upper-seal-supporting metal plate  3660  (seal-supporting member) for supporting an upper seal  3520  (sealing member) that prevents the toner T from spilling from between the developing roller  3510  and a housing  3540  that contains the toner T; and as shown in  FIG. 24C  and  FIG. 24D , the upper-seal-supporting metal plate  3660  and both the first side metal plate  3640  and the second side metal plate  3650  were welded through laser spot welding. This, however, is not a limitation. For example, the upper-seal-supporting metal plate  3660  may be connected to the first side metal plate  3640  and the second side metal plate  3650  without being welded through spot welding. 
   However, if the upper-seal-supporting metal plate  3660  and both the first side metal plate  3640  and the second side metal plate  3650  are connected through laser spot welding, then since the blade-supporting metal plate  3630  and the upper-seal-supporting metal plate  3660  are connected to both the first side metal plate  3640  and the second side metal plate  3650  through laser spot welding, it becomes possible to increase the strength of the holder  3620  when connecting the first side metal plate  3640 , the second side metal plate  3650 , the blade-supporting metal plate  3630 , and the upper-seal-supporting metal plate  3660 . The foregoing embodiment is therefore more preferable in this sense. 
   Further, in the foregoing embodiment, the adjustment of the attachment position of the blade-supporting metal plate  3630  with respect to the first side metal plate  3640  and the second side metal plate  3650  was carried out such that the distance between the edge  3561   a  of the rubber section  3561  and the center  3642   a  of the bearing hole  3642  of the first side metal plate  3640  (or the center  3652   a  of the bearing hole  3652  of the second side metal plate  3650 ) takes a predetermined value (Lx in the X direction and Ly in the Y direction) as shown in  FIG. 27 . This, however, is not a limitation. For example, the attachment position may be adjusted such that the distance between the edge of the rubber section  3561  and the central axis of the developing roller  3510  takes a predetermined value in a state where the rubber section  3561  is made to abut against the developing roller  3510 . 
   However, if the attachment position is adjusted such that the distance between the edge  3561   a  of the rubber section  3561  and the center  3642   a  of the bearing hole  3642  (or the center  3652   a  of the bearing hole  3652 ) takes a predetermined value (Lx in the X direction and Ly in the Y direction), then it becomes possible to arrange the blade-supporting metal plate  3630  in an appropriate position with respect to the first side metal plate  3640  and the second side metal plate  3650  at a higher precision, compared to adjusting the attachment position in a state where the rubber section  3561  is made to abut against the developing roller  3510 . The foregoing embodiment is therefore more preferable in this sense. 
   Further, the positions where the first bent section  3632  of the blade-supporting metal plate  3630  and the first side metal plate  3640 , and also the second bent section  3633  of the blade-supporting metal plate  3630  and the second side metal plate  3650 , are welded through laser spot welding are not limited to those positions shown in  FIG. 24A  and  FIG. 24B . For example, as shown in  FIG. 30 , a welding hole  3656  may be provided in the second side metal plate  3650 , and the welding hole  3656  and the bent surface  3633   a  of the second bent section  3633  may be welded through laser spot welding (the dots indicated by W in  FIG. 30 ). It should be noted that  FIG. 30  is a diagram showing another example. Further, the first side metal plate  3640  and the bent surface  3632   a  may also be welded through laser spot welding at a similar position as that described above. 
   &lt;&lt;&lt;Other Embodiments&gt;&gt;&gt; 
   In the foregoing, an image forming apparatus etc. of the present invention was described according to embodiments thereof. However, the foregoing embodiments of the invention are for the purpose of elucidating the present invention and are not to be interpreted as limiting the present invention. The present invention can be altered and improved without departing from the gist thereof, and needless to say, the present invention includes its equivalents. 
   In the foregoing embodiments, an intermediate transferring type full-color laser beam printer was described as an example of the image forming apparatus, but the present invention is also applicable to various types of image forming apparatuses, such as full-color laser beam printers that are not of the intermediate transferring type, monochrome laser beam printers, copying machines, and facsimile machines. 
   Further, in the foregoing embodiments, an image forming apparatus provided with a rotary-type developing device was described as an example. This, however, is not a limitation, and the present invention is applicable to, for example, image forming apparatuses provided with tandem-type developing devices. 
   Further, in the foregoing embodiments, the photoconductor, as an image bearing body, was described as having a structure in which a photoconductive layer was provided on the outer peripheral surface of a cylindrical, conductive base. This, however, is not a limitation. The photoconductor can be, for example, a so-called photoconductive belt structured by providing a photoconductive layer on a surface of a belt-like conductive base. 
   &lt;&lt;&lt;Configuration of Image Forming System Etc.&gt;&gt;&gt; 
   Next, an embodiment of an image forming system, which serve as an example of an embodiment of the present invention, is described with reference to the  FIG. 31  and  FIG. 32 . 
     FIG. 31  is an explanatory drawing showing an external structure of an image forming system. The image forming system  700  comprises a computer  702 , a display device  704 , a printer  706 , an input device  708 , and a reading device  710 . 
   In this embodiment, the computer  702  is accommodated in a mini-tower type housing, but this is not a limitation. A CRT (cathode ray tube), a plasma display, or a liquid crystal display device, for example, is generally used as the display device  704 , but this is not a limitation. The printer described above is used as the printer  706 . In this embodiment, a keyboard  708 A and a mouse  708 B are used as the input device  708 , but this is not a limitation. In this embodiment, a flexible disk drive device  710 A and a CD-ROM drive device  710 B are used as the reading device  710 , but the reading device is not limited to these, and other devices such as an MO (magneto optical) disk drive device or a DVD (digital versatile disk) may be used. 
     FIG. 32  is a block diagram showing a configuration of the image forming system shown in  FIG. 31 . Further provided are an internal memory  802 , such as a RAM inside the housing accommodating the computer  702 , and an external memory such as a hard disk drive unit  804 . 
   It should be noted that in the above description, an example in which the image forming system is structured by connecting the printer  706  to the computer  702 , the display device  704 , the input device  708 , and the reading device  710  was described, but this is not a limitation. For example, the image forming system can be made of the computer  702  and the printer  706 , and the image forming system does not have to comprise any one of the display device  704 , the input device  708 , and the reading device  710 . 
   Further, for example, the printer  706  can have some of the functions or mechanisms of the computer  702 , the display device  704 , the input device  708 , and the reading device  710 . As an example, the printer  706  may be configured so as to have an image processing section for carrying out image processing, a displaying section for carrying out various types of displays, and a recording media attach/detach section to and from which recording media storing image data captured by a digital camera or the like are inserted and taken out. 
   As an overall system, the image forming system that is achieved in this way becomes superior to conventional systems.