Patent Publication Number: US-9851653-B2

Title: Charging device and image forming apparatus including movable member to which cleaning member is attached

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2016-007853 filed Jan. 19, 2016 and Japanese Patent Application No. 2016-007852 filed Jan. 19, 2016. 
     BACKGROUND 
     Technical Field 
     The present invention relates to a charging device and an image forming apparatus. 
     SUMMARY 
     According to an aspect of the invention, a charging device includes an electrode, a cleaning member that moves along the electrode and cleans the electrode, a rotating member that is disposed along the electrode, includes a spiral protruding portion on an outer circumferential surface thereof, and circumferentially rotates, and a movable member to which the cleaning member is attached. The movable member includes a first through hole through which the rotating member passes, a first pressed portion that is provided on an inner circumferential surface of the first through hole and pressed by the protruding portion of the rotating member, and a second pressed portion that is disposed at a different position from a position of the first pressed portion in an axial direction of the rotating member and that is disposed such that one or more turns of the protruding portion are positioned between the second pressed portion and the first pressed portion. The second pressed portion is pressed by the protruding portion. Upon receiving driving power from the rotating member, the movable member moves in the axial direction of the rotating member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a view illustrating an exemplary configuration of an image forming apparatus; 
         FIG. 2  is an enlarged view of a charging device; 
         FIG. 3  is a perspective view of the charging device; 
         FIG. 4  is a perspective view of a portion of a movable member where a cylindrical portion is provided; 
         FIG. 5  is a cross-sectional view of the movable member which is taken along the line V-V in  FIG. 4 ; 
         FIGS. 6A and 6B  are views illustrating comparative examples of the movable member; 
         FIG. 7  is a view illustrating another exemplary configuration of the movable member; 
         FIG. 8  is a view illustrating another exemplary configuration of the movable member; 
         FIG. 9  is a cross-sectional view of the movable member which is taken along the line IX-IX in  FIG. 8 ; 
         FIG. 10  is a view illustrating another exemplary configuration of the movable member; and 
         FIG. 11  is a view illustrating another exemplary configuration of the movable member. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a view illustrating an exemplary configuration of an image forming apparatus  1  according to an exemplary embodiment of the present invention. 
     The image forming apparatus  1  illustrated in  FIG. 1  is a so-called tandem type color printer, and includes an image forming device  10  that forms an image based on image data. Further, the image forming apparatus  1  is provided with a main controller  50 . 
     The main controller  50  is configured with a program-controlled central processing unit (CPU), and performs, for example, an operation control of each device and each functional unit provided in the image forming apparatus  1 , a communication with a personal computer, etc., or a processing of image data. 
     Further, the image forming apparatus  1  is provided with a user interface unit  30  that receives an operation input from a user or displays various kinds of information to a user. 
     The image forming device  10  is a functional unit that forms an image by using, for example, an electrophotographic method, and includes four (4) image forming units which include a yellow (Y) image forming unit  11 Y, a magenta (M) image forming unit  11 M, a cyan (C) image forming unit  11 C, and a black (K) image forming unit  11 K. 
     In the following descriptions, the respective image forming units will be referred to as “image forming units  11 ” unless they should be expressed to be particularly discriminated from each other. 
     The image forming unit  11 Y, the image forming unit  11 M, the image forming unit  11 C, and the image forming unit  11 K form a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image, respectively. 
     The image forming units  11  are provided with photoconductor drums  12 , respectively, as an example of image carriers. Each photoconductor drum  12  is formed in a cylindrical shape. In addition, the photoconductor drum  12  is rotatably provided and circumferentially rotates by a motor (not illustrated). The photoconductor drum  12  holds a toner image formed on the outer circumferential surface thereof. 
     More specifically, in the present exemplary embodiment, an electrostatic latent image is formed on the surface of the photoconductor drum  12 , and subsequently, a development is carried out by a toner. Therefore, a toner image is formed on the surface of the photoconductor drum  12 , and the toner image is temporarily held by the photoconductor drum  12 . 
     Further, the image forming units  11  are provided with charging devices  13 , respectively, that charge the surfaces of the photoconductor drums  12 , and exposure devices  14 , respectively, that expose the photoconductor drums  12  charged by the charging devices  13  based on the image data. 
     Further, the image forming units  11  are provided with developing devices  15 , respectively, that develop the electrostatic latent images formed on the photoconductor drums  12  by using color toners, and cleaners  16 , respectively, that clean the surfaces of the photoconductor drums  12  after the transfer. 
     In addition, the image forming units  11  have the same configuration, except for the toners accommodated in the image developing devices  15 . 
     Further, the image forming device  10  is provided with an intermediate transfer belt  20  to which the color toner images formed on the photoconductor drums  12  of the image forming units  11  are transferred, and primary transfer rolls  21  that transfer (primarily transfer) the color toner images formed by the image forming units  11  to the intermediate transfer belt  20 . 
     Further, the image forming device  10  is provided with secondary transfer rolls  22  that transfer (secondarily transfer) the color toner images superposed and transferred onto the intermediate transfer belt  20 , to a recording material P such as paper at one time. Further, the image forming device is provided with a fixing device  60  that fixes the secondarily transferred color toner images onto the recording material P. 
     In the present exemplary embodiment, hereinafter, the region where the secondary transfer rolls  22  are disposed and the color toner images on the intermediate transfer belt  20  are secondarily transferred to the recording material P will be referred to as a secondary transfer region Tr. 
     The operation of the image forming apparatus  1  will be described. 
     When forming an image, the image forming units  11  form black, cyan, magenta, and yellow color toner images, respectively, through the electrophotographic processes. 
     The color toner images formed by the respective image forming units  11  are sequentially and primarily transferred to the intermediate transfer belt  20  by the primary transfer rolls  21 , and toner images with the color toners superposed thereon are formed on the intermediate transfer belt  20 . 
     The toner images on the intermediate transfer belt  20  are transported, with the movement of the intermediate transfer belt  20 , to the secondary transfer region Tr where the secondary transfer rolls  22  are disposed. 
     In a recording material transport system, the recording material P, which has been dispensed by a dispensing roll  41  from a recording material accommodating container  40 , is transported along a transport path and then reaches the secondary transfer region Tr. 
     In the secondary transfer region Tr, the toner images on the intermediate transfer belt  20  are secondarily transferred to the recording material P at one time by a transfer electric field formed by the secondary transfer rolls  22 . 
     Thereafter, the recording material P to which the toner images have been transferred is separated from the intermediate transfer belt  20 , and transported to the fixing device  60  along the transport path. 
     The toner images on the recording material P transported to the fixing device  60  are fixed onto the recording material P by the fixing device  60 . Thereafter, the recording material P is transported to a recording material discharge unit LA. 
       FIG. 2  is an enlarged view of the charging device  13 . 
     As illustrated in  FIG. 2 , the charging device  13  is provided with a shield electrode  2  that extends in the front and rear direction of the image forming apparatus  1  (see  FIG. 1 ) (in the depth direction of the image forming apparatus  1 , that is, in the direction orthogonal to the paper surface in  FIG. 2 ). In other words, the charging device  13  according to the present exemplary embodiment is provided with the shield electrode  2  that extends along the axial direction of each photoconductor drum  12 . 
     The shield electrode  2  is opened at the side thereof directed toward the photoconductor drum  12 . In addition, the shield electrode  2  is made of a metallic material. In addition, the shield electrode  2  includes a plate-shaped upper wall portion  2   a  that extends in the front and rear direction of the image forming apparatus  1 , and a plate-shaped left wall  2   b  and a plate-shaped right wall  2   c  that extend downwardly from the left and right opposite sides of the upper wall portion  2   a , respectively. 
     A wire electrode  111  is provided in the shield electrode  2 . 
     As an example of an electrode, the wire electrode  111  is configured with a wire material, and disposed to face the outer circumferential surface of the photoconductor drum  12 . In addition, the wire electrode  111  is disposed along the axial direction of the photoconductor drum  12 . 
     In addition, as illustrated in  FIG. 2 , a grid electrode  29  is provided in an opening  2   d  of the shield electrode  2 . 
     The grid electrode  29  is disposed to extend in the front and rear direction of the image forming apparatus  1  (in the axial direction of the photoconductor drum  12 ). In addition, the grid electrode  29  is made of a metallic material in a thin-film shape (plate shape). In addition, the grid electrode  29  includes plural through holes, and the portion where the plural through holes is formed has a mesh shape. 
     In the present exemplary embodiment, a voltage is applied between the wire electrode  111  and the shield electrode  2  and between the wire electrode  111  and the grid electrode  29 . Thus, a potential difference occurs between the wire electrode  111  and the shield electrode  2 , and a potential difference occurs between the wire electrode  111  and the grid electrode  29 . 
     Therefore, electrons are emitted from the wire electrode  111 , and the surface of the photoconductor drum  12  is charged. 
     In the present exemplary embodiment, as illustrated in  FIG. 2 , an upper cleaning member  51  and a lower cleaning member  52  are provided as an example of a cleaning member, and move along the wire electrode  111  and clean the wire electrode  111 . 
     In the present exemplary embodiment, a grid cleaner  53  is disposed to face the grid electrode  29  and configured to clean the grid electrode  29 . 
     In the present exemplary embodiment, a movable member  70  is provided to move along the wire electrode  111  and the grid electrode  29 . The upper cleaning member  51 , the lower cleaning member  52 , and the grid cleaner  53  are attached to the movable member  70 , and move together with the movable member  70 . 
     The movable member  70  is provided with a movable member main body  71  that is disposed inside the shield electrode  2  and supports the upper cleaning member  51 , the lower cleaning member  52 , and the grid cleaner  53 . 
     Further, the movable member  70  is provided with a cylindrical portion  81  through which a shaft  6  to be described later passes. 
     In the present exemplary embodiment, an opening  2   e  is formed in the upper wall portion  2   a  of the shield electrode  2 , and a part of the movable member  70  protrudes through the opening  2   e.    
     In the present exemplary embodiment, the cylindrical portion  81  is provided at the protruding portion of the movable member  70 . In other words, in the present exemplary embodiment, the cylindrical portion  81  is provided outside the shield electrode  2 . 
       FIG. 3  is a perspective view of the charging device  13 . In addition,  FIG. 3  omits illustration of the movable member  70 . 
     As illustrated in  FIG. 3 , a rear end block  3  is attached to the rear end (one end portion) of the shield electrode  2 , and a front end block  4  is attached to the front end (the other end portion) of the shield electrode  2 . In addition, in the present exemplary embodiment, cylindrical shaft support units  3   a  and  4   a  are provided at the end portions of the shield electrode  2  and on the top portion of the shield electrode  2  to extend in the front and rear direction. 
     In the present exemplary embodiment, the shaft  6  as an example of a rotating member is rotatably supported by the shaft support units  3   a  and  4   a . The shaft  6  is disposed to extend in the front and rear direction. Additionally, the shaft  6  is disposed along the wire electrode  111  (see  FIG. 2 ) and the grid electrode  29 . In addition, a spiral protruding portion (male thread)  6   a  is formed on the outer circumferential surface of the shaft  6 . 
     The rear end portion of the shaft  6  passes through the shaft support unit  3   a  and extends rearward, and a driven coupling  7  is attached to the rear end portion of the shaft  6 . The driven coupling  7  is connected to a driving coupling  8  provided at the main body side of the image forming apparatus  1 . 
     In the present exemplary embodiment, the driven coupling  7  receives a driving power from the driving coupling  8  that rotates by a motor  9 , and the shaft  6  circumferentially rotates. 
     The grid electrode  29  illustrated in  FIG. 2  is supported by the front end block  4  and the rear end block  3 . In addition, the grid electrode  29  is stretched in the longitudinal direction by the front end block  4  and the rear end block  3 , and a tension is applied to the grid electrode  29 . 
     One end portion of the wire electrode  111  in the front and rear direction as illustrated in  FIG. 2  is fixed to the front end block  4 , and the other end portion of the wire electrode  111  is fixed to the rear end block  3 . 
       FIG. 4  is a perspective view of a portion of the movable member  70  where the cylindrical portion  81  is provided.  FIG. 5  is a cross-sectional view of the movable member  70  which is taken along the line V-V in  FIG. 4 . In addition,  FIG. 5  illustrates the shaft  6  together. 
     As illustrated in  FIG. 4 , the movable member  70  is provided with the cylindrical portion  81 . In addition, a through hole  91  (which is an example of a first through hole) is provided inside the cylindrical portion  81  to allow the shaft  6  to pass therethrough. 
     As illustrated in  FIG. 5 , a first pressed portion  110  is provided to protrude from the inner circumferential surface of the cylindrical portion  81  and pressed by the protruding portion  6   a  of the shaft  6 . 
     As illustrated in  FIGS. 4 and 5 , the movable member  70  is provided with a second pressed portion  120  that is pressed by the protruding portion  6   a  of the shaft  6 . 
     The second pressed portion  120  is disposed at a different position from the position of the first pressed portion  110  in the axial direction of the shaft  6 . In addition, the second pressed portion  120  is disposed such that one or more turns of the protruding portion  6   a  are positioned between the first pressed portion  110  and the second pressed portion  120 . 
     In the present exemplary embodiment, an opposite pressed portion  150  is provided at the opposite side to the first pressed portion  110  with the shaft  6  interposed therebetween. 
     Like the first pressed portion  110 , the opposite pressed portion  150  is provided to protrude from the inner circumferential surface of the cylindrical portion  81 . 
     In the present exemplary embodiment, when the shaft  6  rotates, the first pressed portion  110 , the second pressed portion  120 , and the opposite pressed portion  150  are pressed by the protruding portion  6   a . Therefore, the movable member  70  moves along the axial direction of the shaft  6 . 
     When the movable member  70  moves along the axial direction of the shaft  6 , the upper cleaning member  51  (see  FIG. 2 ) and the lower cleaning member  52  move along the wire electrode  111 , and the grid cleaner  53  moves along the grid electrode  29  so that the wire electrode  111  and the grid electrode  29  are cleaned. 
     More specifically, in the present exemplary embodiment, when the movable member  70  moves leftward in  FIG. 5 , the first pressed portion  110  and the second pressed portion  120  are pressed leftward in  FIG. 5  by the protruding portion  6   a  of the circumferentially rotating shaft  6 . 
     When the movable member  70  moves rightward in  FIG. 5 , the opposite pressed portion  150  is pressed rightward in  FIG. 5  by the protruding portion  6   a  of the shaft  6 . 
     Therefore, the movable member  70  moves along the axial direction of the shaft  6  so that the wire electrode  111  and the grid electrode  29  are cleaned. 
     Here, in the configuration of the present exemplary embodiment, the shaft  6  passes through the through hole  91 , and the cylindrical portion  81  is provided to cover the entire circumference of the shaft  6 . 
     Therefore, the displacement of the movable member  70  with respect to the shaft  6  hardly occurs, and the movable member  70  is suppressed from being separated from the shaft  6 . 
       FIGS. 6A and 6B  are views illustrating comparative examples of the movable member. 
     In the comparative example illustrated in  FIG. 6A , a shaft  600  passes through a movable member  700  with an opening  700 A formed on the top portion thereof. In addition, in the comparative example illustrated in  FIG. 6B , an opening  700 A is provided at the lateral side of a movable member  700 . 
     In the configuration in which the opening  700 A is provided as represented in the comparative examples, the displacement of the movable member  700  with respect to the shaft  600  easily occurs, and the movable member  700  is easily separated from the shaft  600 . When a change occurs in the movable member  700 , the movable member  700  becomes difficult to move, and in some instances, the movable member  700  is stopped. Further, when the movable member  700  is separated from the shaft  600 , the movable member  700  is stopped. 
     Here, although it may be considered to cover the opening  700 A with a separate member, this configuration increases the number of components. Further, the configuration causes complexity of the assembling processes. 
     In contrast, in the present exemplary embodiment, the shaft  6  passes through the cylindrical portion  81 , and the displacement of the movable member  70  with respect to the shaft  6  is inhibited. Further, the movable member  70  is suppressed from being separated from the shaft  6 . 
     In the present exemplary embodiment, the movable member  70  is made of a resin material, and the movable member main body  71  and the cylindrical portion  81 , which are illustrated in  FIG. 2 , are integrally formed. Therefore, the number of components is reduced in comparison with the comparative example in which the opening  700 A is covered with a separate member. 
     In the present exemplary embodiment, as illustrated in  FIG. 5 , one or more turns of the protruding portion  6   a  are positioned between the first pressed portion  110  and the second pressed portion  120 . 
     Therefore, in the present exemplary embodiment, tilting of the movable member  70  with respect to the shaft  6  hardly occurs, and the movable member  70  more stably moves. 
     Here, for example, in a configuration in which the second pressed portion  120  is not provided, and two pressed portions, such as the first pressed portion  110  and the opposite pressed portion  150 , are provided at positions where the protruding portion  6   a  is interposed, the movable member  70  may easily tilt. Further, in this case, the straight movement stability of the movable member  70  is deteriorated, or the sliding movement resistance acting on the movable member  70  increases. 
     In contrast, in the configuration in which the two pressed portions, i.e., the first pressed portion  110  and the second pressed portion  120  are provided such that one or more turns of the protruding portion  6   a  are positioned therebetween, as in the present exemplary embodiment, the movable member  70  is difficult to tilt, and the straight movement stability of the movable member  70  increases. 
     In the configuration illustrated in  FIG. 4 , a support piece  190  is provided to extend along the axial direction of the shaft  6  (not illustrated in  FIG. 4 ) and configured to support the second pressed portion  120 . 
     The support piece  190  is vertically disposed. In other words, the support piece  190  is disposed along the protruding direction of the second pressed portion  120 . 
     More specifically, the second pressed portion  120  protrudes downwardly from the upper side in  FIG. 4 , and the support piece  190  is also disposed to be directed downward from the upper side in  FIG. 4 . 
     Additionally, the support piece  190  is disposed such that the short length direction of the support piece  190  conforms to the vertical direction. In this case, the displacement of the second pressed portion  120  hardly occurs. 
     Here, for example, as illustrated in  FIG. 7  (illustrating another exemplary configuration of the movable member  70 ), it may be considered that the support piece  190  is positioned above the shaft  6  (not illustrated in  FIG. 7 ). 
     That is, it may be considered that the support piece  190  is provided to follow the direction orthogonal to the protruding direction of the second pressed portion  120 . 
     In other words, it may be considered that the support piece  190  is provided such that the short length direction of the support piece  190  is orthogonal to the protruding direction of the second pressed portion  120 . 
     Here, in the configuration illustrated in  FIG. 7 , the support piece  190  is easily bent in the vertical direction in  FIG. 7 , and the displacement of the second pressed portion  120  (displacement in the direction away from the shaft  6 ) easily occurs, as compared to the configuration illustrated in  FIG. 4 . In this case, the driving power becomes difficult to be transmitted from the shaft  6  to the movable member  70 . 
       FIG. 8  is a view illustrating another exemplary configuration of the movable member  70 . In addition, as in the above descriptions,  FIG. 8  illustrates a portion of the movable member  70  where the cylindrical portion  81  is provided.  FIG. 9  is a cross-sectional view of the movable member  70  taken along the line IX-IX in  FIG. 8 .  FIG. 9  also illustrates the shaft  6  as in the above descriptions. 
     In this exemplary configuration, as illustrated in  FIG. 8 , a second cylindrical portion  82  is provided, and a second through hole  92  is provided inside the second cylindrical portion  82  to allow the shaft  6  to pass therethrough. 
     The second cylindrical portion  82  is disposed in a state of being spaced apart from the cylindrical portion  81  (hereinafter, referred to as a “first cylindrical portion  81 ”). In addition, the second cylindrical portion  82  is disposed at a different position from the position of the first cylindrical portion  81  in the axial direction of the shaft  6  (not illustrated in  FIG. 8 ). 
     In this exemplary configuration, as illustrated in  FIG. 9 , the second pressed portion  120  is provided on the inner circumferential surface of the second through hole  92 . 
     As in the above descriptions, the second pressed portion  120  is disposed such that one or more turns of the protruding portion  6   a  are positioned between the first pressed portion  110  and the second pressed portion  120 . 
     Here, in the exemplary configuration illustrated in  FIG. 9 , when the movable member  70  moves leftward in  FIG. 9 , the first pressed portion  110  is pressed by the protruding portion  6   a  of the shaft  6 . In addition, when the movable member  70  moves rightward in  FIG. 9 , the second pressed portion  120  is pressed by the protruding portion  6   a  of the shaft  6 . Therefore, the movable member  70  moves along the axial direction of the shaft  6 , and the wire electrode  111  and the grid electrode  29  are cleaned. 
     In the configuration illustrated in  FIG. 9 , when the movable member  70  moves leftward (in one direction) in  FIG. 9  along the axial direction of the shaft  6 , the first pressed portion  110  is pressed by the protruding portion  6   a  of the shaft  6 . In this case, the second pressed portion  120  is spaced apart from the protruding portion  6   a.    
     Additionally, in the present exemplary embodiment, when the movable member  70  moves in one direction (leftward in  FIG. 9 ), the first pressed portion  110 , which is positioned further downstream in the one direction than the second pressed portion  120 , is pressed by the protruding portion  6   a , and in this case, the second pressed portion  120  is spaced apart from the protruding portion  6   a.    
     Therefore, for example, the movable member  70  more stably moves, than the case in which the second pressed portion  120  is pressed by the protruding portion  6   a , and the first pressed portion  110  is spaced apart from the protruding portion  6   a.    
     When the movable member  70  moves in the opposite direction (rightward in  FIG. 9 , and the opposite direction to the one direction), the second pressed portion  120 , which is positioned further downstream than the first pressed portion  110  in the opposite direction, is pressed by the protruding portion  6   a  of the shaft  6 . In this case, the first pressed portion  110  is spaced apart from the protruding portion  6   a.    
     Therefore, for example, the movable member  70  more stably moves, than the case in which the first pressed portion  110  is pressed by the protruding portion  6   a , and the second pressed portion  120  is spaced apart from the protruding portion  6   a.    
     In the exemplary configuration illustrated in  FIG. 9 , two through holes are provided to allow the shaft  6  to pass therethrough so that the displacement of the movable member  70  with respect to the shaft  6  hardly occurs, as compared to the case in which one through hole is provided. 
     In the present exemplary embodiment, the second pressed portion  120  is provided on the inner circumferential surface of the second through hole  92  so that the displacement of the second pressed portion  120  with respect to the shaft  6  hardly occurs, as compared to the configuration in  FIG. 4  in which no second pressed portion  120  is provided on the inner circumferential surface of the through hole. 
     When the displacement of the second pressed portion  120  with respect to the shaft  6  hardly occurs, the driving power is easily transmitted from the shaft  6  to the second pressed portion  120 . 
     In addition, in manufacturing the movable member  70  illustrated in  FIGS. 8 and 9 , three molds including a first mold K 1  to a third mold K 3  are prepared as illustrated in  FIG. 9 . 
     The first mold K 1  is disposed at the portion where the through hole  91  is formed. When injection of resin is ended and the first cylindrical portion  81  is formed, the first mold K 1  moves in the direction indicated by the arrow  9 A in  FIG. 9 . Additionally, the first mold K 1  moves in the direction opposite to the side where the first pressed portion  110  is provided. 
     The second mold K 2  is disposed at the portion where the second through hole  92  is formed. When injection of resin is ended and the second cylindrical portion  82  is formed, the second mold K 2  moves in the direction indicated by the arrow  9 B in  FIG. 9 . Additionally, the second mold K 2  moves in the direction opposite to the side where the second pressed portion  120  is provided. 
     The third mold K 3  is disposed between the first cylindrical portion  81  and the second cylindrical portion  82 . When injection of resin is ended and the first cylindrical portion  81  and the second cylindrical portion  82  are formed, the third mold K 3  moves in the direction indicated by the arrow  9 C in  FIG. 9 . 
       FIG. 10  is a view illustrating another exemplary configuration of the movable member  70 . In addition,  FIG. 10  omits illustration of the shaft  6 . 
     In this exemplary configuration, the first pressed portion  110  is provided at the central portion of the first cylindrical portion  81  in the longitudinal direction thereof, and the second pressed portion  120  is provided at the central portion of the second cylindrical portion  82  in the longitudinal direction thereof. In this case, it is necessary to provide molds even at the portions indicated by the reference numerals  10 A and  10 B in  FIG. 10 , which makes the mold structure complicated. 
     In contrast, in the exemplary configuration illustrated in  FIG. 9 , the first pressed portion  110  is provided at the end portion of the first cylindrical portion  81  in the axial direction thereof, and the second pressed portion  120  is provided at the end portion of the second cylindrical portion  82  in the axial direction thereof so that it is unnecessary to provide the molds indicated by the reference numerals  10 A and  10 B. 
       FIG. 11  is a view illustrating another exemplary configuration of the movable member  70 . 
     In this exemplary configuration, the distance between the first cylindrical portion  81  and the second cylindrical portion  82  further increases, as compared to the exemplary configuration illustrated in  FIG. 9 . 
     In this exemplary configuration, a third pressed portion  130  is provided on the inner circumferential surface of the first cylindrical portion  81  where the first pressed portion  110  is provided, to be pressed by the protruding portion  6   a  of the shaft  6 . 
     Further, a fourth pressed portion  140  is provided on the inner circumferential surface of the second cylindrical portion  82  where the second pressed portion  120  is provided, to be pressed by the protruding portion  6   a  of the shaft  6 . 
     The first pressed portion  110  is provided to protrude downwardly from the ceiling portion of the inner circumferential surface of the first cylindrical portion  81 , and the third pressed portion  130  is provided to protrude upwardly from the bottom portion of the inner circumferential surface of the first cylindrical portion  81 . 
     The same configuration is applied to the second cylindrical portion  82 , such that the second pressed portion  120  is provided to protrude downwardly from the ceiling portion of the inner circumferential surface of the second cylindrical portion  82 , and the fourth pressed portion  140  is provided to protrude upwardly from the bottom portion of the inner circumferential surface of the second cylindrical portion  82 . 
     Here, in the exemplary configuration illustrated in  FIG. 11 , when the movable member  70  moves leftward in  FIG. 11 , the first pressed portion  110  and the fourth pressed portion  140  are pressed by the protruding portion  6   a  of the shaft  6 . In addition, when the movable member  70  moves rightward in  FIG. 11 , the second pressed portion  120  and the third pressed portion  130  are pressed by the protruding portion  6   a  of the shaft  6 . 
     Here, in the exemplary configuration illustrated in  FIG. 11 , since the two pressed portions are provided in the first cylindrical portion  81  and the second cylindrical portion  82 , respectively, the displacement of the movable member  70  with respect to the shaft  6  is further difficult to occur. More specifically, the displacement of the movable member  70  with respect to the shaft  6  hardly occurs in comparison with the case in which a single pressed portion is provided on each of the inner circumferential surface of the first cylindrical portion  81  and the inner circumferential surface of the second cylindrical portion  82 . 
     In particular, in the configuration illustrated in  FIG. 11 , one of the two pressed portions provided on each of the first cylindrical portion  81  and the second cylindrical portion  82  protrudes downwardly from the upper side, and the other one thereof protrudes upwardly from the lower side, such that the protruding directions of the two pressed portions are different from each other. 
     In this case, the displacement of the movable member  70  with respect to the shaft  6  hardly occurs, for example, in comparison with the case in which the two pressed portions protrude downwardly from the upper side such that the protruding directions of the two pressed portions are in parallel with each other. 
     In manufacturing the movable member  70  illustrated in  FIG. 11 , four molds K including a first mold K 5  to a fourth mold K 8  are prepared as illustrated in  FIG. 11 . 
     The first mold K 5  and the second mold K 6  are disposed at the portion where the first cylindrical portion  81  is formed. 
     When injection of resin is ended and the first cylindrical portion  81  is formed, the first mold K 5  moves in the direction indicated by the arrow  11 A in  FIG. 11 . Additionally, the first mold K 5  moves in the direction opposite to the side where the third pressed portion  130  is provided. 
     When injection of resin is ended and the first cylindrical portion  81  is formed, the second mold K 6  moves in the direction indicated by the arrow  11 B in  FIG. 11 . More specifically, the second mold K 6  moves in the direction opposite to the side where the first pressed portion  110  is provided, and further moves upwardly. 
     The third mold K 7  and the fourth mold K 8  are disposed at the portion where the second cylindrical portion  82  is formed. 
     When injection of resin is ended and the second cylindrical portion  82  is formed, the third mold K 7  moves in the direction indicated by the arrow  11 C in  FIG. 11 . In addition, the third mold K 7  moves in the direction opposite to the side where the second pressed portion  120  is provided. 
     When injection of resin is ended and the second cylindrical portion  82  is formed, the fourth mold K 8  moves in the direction indicated by the arrow  11 D in  FIG. 11 . In addition, the fourth mold K 8  moves in the direction opposite to the side where the fourth pressed portion  140  is provided, and further moves upwardly. 
     Here, in the exemplary configuration illustrated in  FIG. 11 , it is necessary to move the second mold K 6  and the fourth mold K 8  in the axial direction of the first cylindrical portion  81  and the second cylindrical portion  82 , and it is necessary to increase the distance between the first cylindrical portion  81  and the second cylindrical portion  82  in comparison with the configuration illustrated in  FIG. 9 . 
     In the exemplary configuration illustrated in  FIG. 9 , the third mold K 3  has only to move upwardly as indicated by the arrow  9 C. However, in the exemplary configuration illustrated in  FIG. 11 , a space is required to move the second mold K 6  and the fourth mold K 8  in the axial direction of the first cylindrical portion  81  and the second cylindrical portion  82 , and as a result, the distance between the first cylindrical portion  81  and the second cylindrical portion  82  increases. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.