JP2011123419A - Charger and image forming apparatus with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the protrusions of the discharge electrode from being deformed by a cleaning member used for cleaning the discharge electrode, in a charger for charging a body to be charged such as a photoreceptor drum. <P>SOLUTION: In a configuration where a holder 81, holding the cleaning member for the discharge electrode 53 while the cleaning member is in contact with a side of the electrode 53, is movably supported along the lengthwise direction of a shield case 50, a projection 91 and a recess 85 are provided on the opposite faces of a first support member 51, supporting one end of the discharge electrode 53, and the holder 81. When the holder 81 moves up to a standby position where it contacts the first support member 51, the protrusion 91 fits into a recess 85, and thereby the holder 81 is held by the first support member 51 in the standby position. This restricts the holder 81 from laterally bending the teeth tips 531 of the discharge electrode 53. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a charging device for charging an object to be charged such as a photoconductor in an image forming apparatus and an image forming apparatus including the charging device, and more particularly, a mechanism for cleaning a charging electrode having a plurality of sharp protrusions provided in the charging device. Regarding improvements.

  An electrophotographic image forming apparatus such as a copying machine includes a charging device for charging the surface of a photosensitive drum. The charging device is provided with a discharge electrode that is elongated along the axial direction of the photosensitive drum, and is provided with a large number of sharpened protrusions such as a sawtooth shape and a pin shape along the longitudinal direction. There is a configuration in which it is arranged opposite to the drum. It is desirable that the amount of corona discharge discharged from the discharge electrode toward the photosensitive drum is stable over a long period of time.

  However, if toner or dust floating in the image forming apparatus is gradually accumulated on the tip of the projection of the discharge electrode due to long-term use and becomes dirty, corona ions released from the discharge electrode are applied to the photosensitive drum. The amount of inflow tends to be unstable due to a decrease in the amount of inflow or a variation in the amount of corona ions flowing between the projections that are not soiled. When the amount of discharge becomes unstable, there arises a disadvantage that uneven charging occurs on the surface of the photosensitive drum.

  Thus, Patent Document 1 discloses a charging device including a cleaning unit that cleans dirt such as toner adhering to a discharge electrode. The charging device of Patent Document 1 includes a sawtooth discharge electrode, a shield case that is long in the axial direction of the photosensitive drum, surrounds the discharge electrode, and has a surface facing the photosensitive drum, and a shield case. A pair of support members are provided at both ends in the longitudinal direction and support both ends of the discharge electrode.

In the shield case, there is a cleaning part consisting of a cleaning member for cleaning the discharge electrode and a holder for holding the cleaning member in contact with both sides of the discharge electrode, and the pins provided on the holder are on both sides of the shield case. The plate is fitted into a long hole provided along the longitudinal direction of the plate, and the holder is supported so as to be movable along the longitudinal direction of the shield case.
As the holder moves, the cleaning member moves so as to rub the sawtooth of the discharge electrode, and the cleaning member cleans dirt such as toner adhering to the sawtooth of the discharge electrode. The cleaning unit is normally stopped at a standby position that is one end in the longitudinal direction of the shield case when the cleaning operation is not executed.

JP 2006-337960 A

In the configuration of the charging device in Patent Document 1, since the holder pin of the cleaning unit is only fitted in the long hole of the shield case, the movement of the holder in the axial direction of the pin (the direction orthogonal to the longitudinal direction of the shield case) Is not regulated.
For this reason, for example, when vibration generated from a drive mechanism such as a motor provided in the image forming apparatus is transmitted to the charging device during the image forming operation, the shield case and the holder constituting the charging device also vibrate. Since the movement of the pin in the axial direction is not restricted, the pin may move differently from the shield case in the axial direction of the pin.

Since the shield case and the discharge electrode are integrated via a pair of support members, if the holder tries to move in the axial direction of the pin with respect to the shield case due to the vibration of the image forming apparatus, the teeth of the sawtooth of the discharge electrode First, a force acts to bend the tooth tip in a direction orthogonal to the longitudinal direction of the shield case.
The discharge electrode is an extremely thin metal long one having a thickness of several microns to several tens of microns, and is easily twisted even with a slight force, and the tooth tip is easily bent. Therefore, if the discharge electrode continues to receive a force in a direction perpendicular to the side surface of the discharge electrode from the holder, the discharge electrode may eventually be twisted or the tooth tip may be bent. When the discharge electrode is twisted or bent, the direction of the tooth tip relative to the photosensitive drum changes.

Since the tooth tip of the discharge electrode becomes the output end of corona discharge, if the direction of the tooth tip with respect to the photosensitive drum changes, the charge distribution on the surface of the photosensitive drum becomes non-uniform in the drum axis direction and uneven charging occurs. It will be. When the charging unevenness occurs, the quality of the formed image is deteriorated.
An object of the present invention is to prevent a cleaning unit that cleans a discharge electrode from deforming the tip of a projection of a discharge electrode due to vibration of an image forming apparatus or the like.

  In order to achieve the above object, a charging device according to the present invention is a charging device for charging the surface of a member to be charged provided in an image forming apparatus, and is a long shape that performs corona discharge for charging the member to be charged. A plurality of sharp projections arranged in the longitudinal direction, and a discharge electrode arranged so that the tip of the projection faces the charged body, and cleaning for cleaning the discharge electrode A member, a holder for holding the cleaning member in contact with the discharge electrode, guide means for guiding the holder in the longitudinal direction of the discharge electrode from the standby position, and when the holder is in the standby position, And a transition regulating means for regulating a transition in a direction in which at least the tip of the projection of the discharge electrode is bent.

  In addition, a first support member and a second support member that respectively support both ends in the longitudinal direction of the discharge electrode are provided, and the guide means is a region between the first support member and the second support member. The standby position is a position at one end or both ends in the longitudinal direction in the region, and the holder faces at least one support member of the first support member and the second support member. The first convex portion or the first concave portion is provided in the portion, and the transition restricting means is provided on at least one of the first support member and the second support member. It is the 2nd convex part inserted in the 2nd concave part or the 1st concave part into which a convex part is inserted, It is characterized by the above-mentioned.

Further, the holder is provided with the first concave portion and the support member is provided with the second convex portion.
Further, the cross-sectional shape of the convex portion is a polygon.
Further, the convex portion is characterized by comprising a pair of protrusions arranged side by side in the thickness direction of the discharge electrode.

In addition, the tip of the protrusion is provided with a taper whose diameter decreases toward the tip.
And a shield case that is long in the longitudinal direction of the discharge electrode, surrounds the discharge electrode, and is open at a surface facing the charged body. The first support member has one end in the longitudinal direction of the shield case. The second support member is attached to the other end in the longitudinal direction of the shield case, the holder is located in the shield case, and the guide means is provided in the holder It comprises a guide piece and a long hole provided in the shield case along the longitudinal direction and into which the guide piece of the holder is fitted.

  In addition, the long hole is provided in the bottom part facing the opening of the shield case, and when the long hole is divided into both the end part and the central part in the longitudinal direction, the width of at least one end is M1, and the central part is When the width is M2, there is a relationship of M2 <M1, the guide piece is provided on the bottom of the holder facing the long hole, and the tip of the guide piece projects out of the shield case through the long hole. In the portion where the holder and the guide piece are connected, a narrow constricted portion is provided in the width direction, the width direction length of the constricted portion is R1, the width direction length of the guide piece is R2, When the width direction length of the bottom of the holder is R3, the relationship of R1 <M2 <R2 <M1 <R3 is satisfied.

  In addition, the first support member includes a shield case that is long in the longitudinal direction of the discharge electrode, surrounds the discharge electrode, and has an opening on a surface facing the charged body. The first support member has one end in the longitudinal direction of the shield case. The second support member is attached to the other end in the longitudinal direction of the shield case, the holder is located in the shield case, and the convex portion is the first support. The first and second projections having flexibility are provided on the surface of the member facing the holder and arranged side by side in the thickness direction of the discharge electrode. Before the first support member is attached to the shield case, the first support member has a notch into which the bottom portions of the first and second protrusions are fitted at the position where the support member is attached. The first protrusion of the second protrusion When the width of the projection from the first surface on the opposite side of the surface facing the first projection to the second surface on the opposite side of the surface facing the first projection is the first value, the second projection is mounted. Later, when the first and second protrusions are fitted into the notches at the time of mounting, the first and second protrusions are deflected by the mutually approaching forces acting on each of them, thereby reducing the width of the protrusions. The second value is narrower than the first value.

  The present invention is an image forming apparatus including a charging unit that charges the surface of an object to be charged for image formation, and includes the above-described charging device as the charging unit.

  In this way, since the movement of the holder that supports the cleaning member is restricted, even if the charging device vibrates during the image forming operation in the image forming apparatus, the deformation of the discharge electrode due to the vibration of the holder can be prevented. it can.

FIG. 2 is a diagram illustrating a schematic configuration of an entire printer including a charger. It is a side view of a charger. It is a top view of the edge part of the apparatus back side in a charger. FIG. 4 is an arrow end view when the charger is cut along line AA in FIG. 3. FIG. 3 is an enlarged side view showing a rear end portion of the charger with a part thereof cut away. It is a perspective view which shows the edge part of the apparatus back side of a charger. It is a top view of the edge part of the apparatus rear side of the shield case with which a charger is equipped. It is a figure which shows the structure of the 1st supporting member with which a charger is equipped. It is a figure which shows the structure of the cleaning part with which a charger is equipped. It is a figure which shows a mode that the cleaning part is guided toward the standby position. It is a figure which shows a mode that the cleaning part has stopped in the standby position. (A) is a figure which shows a mode that the cleaning part is guided toward a return position, (b) is a figure which shows a mode that the cleaning part has stopped in a return position, (c) FIG. 6 is a schematic diagram illustrating a state where the cleaning unit is inclined by an angle θ from a vertical posture, and FIG. 6D is a schematic diagram illustrating that the inclination angle is 2θ when the cleaning unit returns. It is a figure which shows a mode that the bottom part of a processus | protrusion is fitted by the notch provided in the bottom plate of a shield case, when the processus | protrusion of a 1st support member is mounted | worn with a shield case.

Hereinafter, embodiments of the charging device and the image forming apparatus according to the present invention will be described by taking a tandem color digital printer (hereinafter simply referred to as “printer”) as an example.
(1) Overall Configuration of Printer FIG. 1 is a diagram showing the overall configuration of the printer 10.
As shown in FIG. 1, the printer 10 forms an image by a well-known electrophotographic system, and includes an image processing unit 11, a feeding unit 12, a fixing unit 13, and a control unit 14.

  When the printer 10 is connected to a network (for example, LAN) and receives a print job execution instruction from an external terminal device (not shown), the printer 10 starts from yellow, magenta, cyan, and black colors based on the instruction. The color image formation is executed. Hereinafter, the reproduction colors of yellow, magenta, cyan, and black are represented as Y, M, C, and K, and Y, M, C, and K are added as subscripts to the numbers of the components related to the reproduction colors.

The image processing unit 11 includes image forming units 20Y, 20M, 20C, and 20K, an intermediate transfer belt 21, and the like corresponding to each of Y to K colors.
The image forming unit 20Y includes a photosensitive drum 1, a charger 2 disposed around the photosensitive drum 1, an exposure unit 3, a developing unit 4, a primary transfer roller 5, a cleaner 6 for cleaning the photosensitive drum 1, and the like. A Y-color toner image is formed on the photosensitive drum 1. This configuration is the same for the other image forming units 20M to 20K, and a corresponding color toner image is formed.

The intermediate transfer belt 21 is an endless belt, is stretched around a driving roller 22 and a driven roller 23, and is driven to rotate in the direction of the arrow in FIG.
The feeding unit 12 includes a paper feed cassette 31 that stores the paper S, a feed roller 32 that feeds the recording sheets S in the paper feed cassette 31 one by one onto the transport path 37, and a transport that transports the fed paper S. A roller pair 33 and a timing roller pair 34 are provided. Further, on the rear side of the timing roller pair 34 in the sheet conveying direction, a secondary transfer roller 35 that is pressed against the driving roller 22 with the intermediate transfer belt 21 interposed therebetween is disposed.

The fixing unit 13 includes a fixing roller and a pressure roller.
The control unit 14 converts an image signal from an external terminal device into a digital signal for Y to K colors, and generates a drive signal for driving the laser diode of the exposure unit 3 of the image forming units 20Y to 20K. By the generated drive signal, the laser diode of the exposure unit 3 is driven for each image forming unit, the laser beam L is emitted, and the photosensitive drum 1 is exposed and scanned.

Before the exposure scan, the photosensitive drum 1 is uniformly charged by the charger 2 for each image forming unit, and an electrostatic latent image is formed on the photosensitive drum 1 by the exposure of the laser beam L. Is done.
For each image forming unit, the electrostatic latent image on the photosensitive drum 1 is developed with toner by the developing device 4. The toner images of the respective colors are primarily transferred onto the intermediate transfer belt 21 by electrostatic force acting between the primary transfer roller 5 and the photosensitive drum 1. The image forming operations for the respective colors are executed at different timings so that the toner images are superimposed and transferred at the same position on the intermediate transfer belt 21. The respective color toner images superimposed on the intermediate transfer belt 21 are moved to a secondary transfer position, which is a position where the secondary transfer roller 35 is pressed against the intermediate transfer belt 21 by the rotation of the intermediate transfer belt 21.

  The sheet S is fed through the timing roller pair 34 in accordance with the timing of the image forming operation, and the sheet S includes the rotating intermediate transfer belt 21 and the secondary transfer roller pressed against the intermediate transfer belt 21. The toner image on the intermediate transfer belt 21 is secondarily transferred onto the sheet S in a lump by electrostatic force acting between the secondary transfer roller 35 and the drive roller 22.

The sheet S that has passed the secondary transfer position is conveyed to the fixing unit 13 where the toner image is heated and pressurized and fixed on the sheet S, and then discharged through the discharge roller 36 to the storage tray 38. Be contained.
(2) Configuration of Charging Device 2 FIG. 2 is a side view of the charging device 2 and is partially cut away for convenience of explanation.

  As shown in FIG. 2, the charger 2 is long along the axial direction (X direction) of the photosensitive drum 1, and includes a shield case 50, a first support member 51, a second support member 52, The unit includes a discharge electrode 53, a grid electrode 54, a cleaning unit 55, an operation shaft 56, and the like. Further, the charger 2 is configured such that the cleaning unit 55 can move and the discharge electrode 53 can be cleaned by moving the operation shaft 56 along the axial direction of the photosensitive drum 1.

In FIG. 2, the X direction corresponds to a direction parallel to the axial direction of the photosensitive drum 1, and the Z direction corresponds to a direction along the perspective direction of the charger 2 with respect to the photosensitive drum 1. Further, in the X direction of FIG. 2, the first support member 51 side corresponds to the apparatus rear side, and the second support member 51 side corresponds to the apparatus front side. Hereinafter, the configuration of each member of the charger 2 will be specifically described with reference to FIGS.
3 is a front view showing an end portion of the charger 2 on the rear side of the apparatus, and FIG. 4 is an end view taken along the line AA in FIG. FIG. 6 is an enlarged side view showing an end portion of the charger 2 on the rear side of the apparatus with a part thereof cut away, and FIG. 6 is a perspective view showing an end portion of the charger 2 on the rear side of the apparatus. 7 is a plan view of an end portion of the shield case 50 on the apparatus rear side.

3 corresponds to a direction perpendicular to the side surface 532 (FIG. 5) of the discharge electrode 53 that is a plate-like body, and in this embodiment, the direction is perpendicular to the X direction and the Z direction. ing.
(3) Configuration of Shield Case 50 As shown in each drawing, the shield case 50 is a member extending in the X direction, and has a surface facing the photosensitive drum 1 opened, and as shown in FIG. 4, the Y direction. And side plates 71 and 72 facing each other, and a bottom plate 73 connecting the side plates 71 and 72.

The shield case 50 is made of, for example, a plate-like body made of stainless steel having a thickness of 0.5 [mm] and formed into a U-shaped cross section by press working. The shield case 50 surrounds the discharge electrode 53 from three sides and is released from the discharge electrode 53. Shields corona ions from spreading around. As a result, corona ions flow out toward the photosensitive drum 1 through the opening 78 provided on the surface of the shield case 50 facing the photosensitive drum 1.
(4) Configuration of First and Second Support Members 51 and 52 The first support member 51 is attached to the end portion of the shield case 50 on the apparatus rear side. Specifically, positioning is performed by fitting two protrusions (not shown) provided on the bottom of the first support member 51 into two holes 79 (FIG. 7) provided on the bottom plate 73 of the shield case 50. In this state, a screw is inserted into a screw hole (not shown) provided in the bottom portion of the support member 51 through a round hole 791 to fix the screw. The first support member 51 supports end portions of the discharge electrode 53 and the grid electrode 54 on the device rear side.

The second support member 52 is attached to the end of the shield case 50 on the front side of the apparatus, and supports the end of the discharge electrode 53 and the grid electrode 54 on the front side of the apparatus. The mounting of the second support member 52 to the shield case 50 is performed by screwing and fixing similarly to the first support member 52.
The first support member 51 and the second support member 52 are made of a highly insulating resin such as ABS (acrylonitrile butadiene styrene), and the shield case 50, the discharge electrode 53, and the grid electrode 54 are electrically insulated from each other. It is in the state.
(5) Configuration of Discharge Electrode 53 and Grid Electrode 54 The discharge electrode 53 has a long shape in the X direction and is made of a metal plate having a thickness of, for example, about 0.05 mm, and is shown in FIG. Thus, saw-tooth 530 is formed on the side facing the photosensitive drum 1.

The grid electrode 54 is long in the X direction, and is formed into a mesh (net plate) shape by performing a process such as etching on a thin metal plate such as stainless steel.
The discharge electrode 53 and the grid electrode 54 are respectively in the first support member 51 and the second support member 52 in a state where tension is applied to the first support member 51 and the second support member 52 by a tension spring or the like (not shown). Is passed in between.

A high voltage power supply (not shown) is connected to each of the discharge electrode 53 and the grid electrode 54, and a voltage for corona discharge is applied to the discharge electrode 53, and a bias voltage is applied to the grid electrode 54. Thereby, the charged potential on the surface of the photosensitive drum 1 is kept constant.
(6) Configuration of Cleaning Unit 55 The cleaning unit 55 cleans the discharge electrode 53 and is located in the shield case 50. As shown in FIG. 4, the holder 81 and the cleaning members 82 and 83 are arranged. Prepare.

The holder 81 is a quadrangular frame, is made of a highly insulating resin such as ABS, and surrounds the discharge electrode 53 penetrating the frame from four directions.
The cleaning members 82 and 83 are made of, for example, a highly wear-resistant resin such as urethane resin, and are disposed in the frame of the holder 81, sandwiching both side surfaces 532 of the discharge electrode 53, and being in close contact with the side surfaces 532. So as to be held by the holder 81.

A hook 84 is provided at the end (bottom) 89 of the holder 81 on the opposite side to the photosensitive drum 1. The hook 84 protrudes to the outside of the shield case 50 through a long hole 74 (FIG. 7) opened in the bottom plate 73 of the shield case 50, and is connected to the end portion of the operation shaft 56 on the apparatus rear side.
The long hole 74 of the shield case 50 is continuously opened from the attachment position of the first support member 51 to the attachment position of the second support member 52 along the X direction on the bottom plate 73. .

  The width of the long hole 74 is such that when the long hole 74 is divided in the longitudinal direction into an end portion on the front side of the apparatus, a central portion, and an end portion on the rear side, only the end portion on the rear side of the apparatus becomes M1 as shown in FIG. The part on the front side of the apparatus (the center part and the end part on the front side of the apparatus) is M2 (<M1). The widths M1 and M2 are determined in the Y direction (width direction) of each of the constricted portions 891 (FIG. 4) provided in the holder 81, the hook 84, and the bottom portion 89 of the holder 81 that is a connecting portion of the holder 81 and the hook 84. It is decided according to the length.

  That is, as shown in FIG. 4, when the length in the Y direction of the constricted portion 891 is R1, the length in the Y direction of the hook 84 is R2, and the length in the Y direction of the bottom portion 89 of the holder 81 is R3, R1 <M2 <R2 < The magnitude relationship is M1 <R3. By satisfying this relationship, when the cleaning unit 55 is mounted on the shield case 50, there is a relationship of (a) R2 <M1, and therefore, from the outside of the shield case 50 in the same posture as that after the holder 81 is mounted. Inwardly, the holder 81 can be inserted into the wide portion (the portion having the width M1) of the long hole 74 of the shield case 50 until the bottom portion of the holder 81 contacts the bottom plate 73 of the shield case 50. In this case, since there is a relationship of M1 <R3, the holder 81 does not pass through the wide portion of the long hole 74.

  (B) Since there is a relationship of R1 <M2, when the holder 81 is moved in the X direction, the constricted portion 891 of the holder 81 can be fitted into the narrow portion (the portion having a width of M2) of the long hole 74. it can. Thus, the holder 81 is guided and supported so as to be movable along the long hole 74. In this case, since there is a relationship of M2 <R2 and M2 <R3, the holder 81 does not come out of the shield case 50 along the Z direction and can be supported in a stable state.

  The height t (FIG. 4) in the Z direction of the constricted portion 891 is, for example, about 0.8 [mm]. This value corresponds to the critical dimension of the holder 81 during resin molding, and the thickness of the shield case 50 is 0.5 [mm]. Therefore, when the holder 81 is supported by the long hole 74 of the shield case 50, In addition, a gap of 0.3 [mm] is formed in the Z direction with respect to the bottom plate 73 of the shield case 50. Further, from the relationship of R1 <M2 <M1, for example, when R1 = 5.5 [mm], M2 = 5.7 [mm], and M1 = 8.0 [mm], the holder 81 is the bottom plate 73 of the shield case 50. On the other hand, in the Y direction, there is a gap of 2.5 [mm] when positioned in the wide portion and 0.3 [mm] when positioned in the narrow portion.

  Although the discharge electrode 53 is supported by the shield case 50 via the first support member 51 and the second support member 52, it can be said that the discharge electrode 53 is integral. It can move freely with respect to the shield case 50 (that is, the discharge electrode 53) by the existing gap. For this reason, when the vibration generated during image formation is transmitted and the cleaning unit 55 vibrates in the direction along the Y direction (the thickness direction of the discharge electrode) with respect to the discharge electrode 53, the vibration of the cleaning unit 55 is transmitted to the discharge electrode 53. There is a risk that a force in a direction in which the tooth tip 531 of the saw tooth 530 is bent laterally acts to twist the discharge electrode 53 or bend the tooth tip 531.

Therefore, in the present embodiment, as described later, when the cleaning unit 55 is located at the standby position, the movement of the cleaning unit 55 is restricted by the first support member 51, and when the cleaning unit 55 is located at the return position, the second operation is performed. By adopting a configuration that is regulated by the support member 52, the twist of the discharge electrode 53 and the bending of the tooth tip 531 are suppressed.
In the present embodiment, the position when the cleaning unit 55 has moved to the full position on the rear side of the apparatus is referred to as a standby (home) position, and the position when the cleaning section 55 has moved to the full position on the front side of the apparatus is referred to as a return position.
(7) Configuration of Operation Shaft 56 The operation shaft 56 is outside the shield case 50 and is disposed at a position facing the discharge electrode 53 with the bottom plate 73 of the shield case 50 interposed therebetween. It is supported so that it can move along.

  An end of the operation shaft 56 on the rear side of the apparatus is connected to a hook 84 provided on the holder 81. When the operation shaft 56 is moved along the X direction, the holder is interlocked with the movement of the operation shaft 56. 81 moves in the same direction. As the holder 81 moves, the cleaning members 82 and 83 attached to the holder 81 move so as to rub the side surface 532 of the discharge electrode 53, so that toner, dust, or the like adhering to the sawtooth 530 of the discharge electrode 53 is attached. The discharge electrode 53 is cleaned by scraping off the kimono or taking it into the cleaning members 82 and 83.

The movement of the operation shaft 56 can be configured to be driven by an electric motor such as a motor. However, as a simple method, the user or a serviceman grips the end portion of the operation shaft 56 on the front side of the device and moves the operation shaft 56. It is also possible to adopt a configuration in which 56 is reciprocated in the longitudinal direction of the apparatus.
When the discharge electrode 53 is not cleaned, the cleaning unit 55 is waiting (stopped) at the standby position. This standby position is outside the image forming area so as not to interfere with image formation.

When cleaning is performed, the operation shaft 56 moves in the X direction, and the cleaning unit 55 moves in the X direction from the standby position toward the return position. After the cleaning unit 55 reaches the return position, when the movement direction of the operation shaft 56 is reversed (moved in the direction opposite to the X direction), the cleaning unit 55 is moved from the return position toward the standby position. When the cleaning is completed, the cleaning unit 55 is returned to the standby position.
(8) Details of Configuration of First Support Member 51 and Cleaning Unit 55 FIG. 8 is a diagram showing the configuration of the first support member 51, (a) is a perspective view, and (b) is a diagram of (a). The enlarged plan view of the part enclosed with a circle, (c) is an enlarged side view, (d) is an enlarged front view. Moreover, FIG. 9 is a figure which shows the structure of the cleaning part 55, (a) is a perspective view, (b) is a partial expanded front view, (c) is the arrow sectional view in the CC line of (b). FIG.

  As shown in FIG. 8, the first support member 51 includes a housing 90 and a convex portion 91 provided on a surface 95 of the housing 90 on the side facing the holder 81. The housing 90 and the convex portion 91 are: It is formed by integral molding of resin. The convex portion 91 has two protrusions 92 and 93 having substantially the same size. The protrusions 92, 93 are arranged at intervals in the Y direction, and each has a rectangular cross section. Of the four corners, the protrusion 92 has a side opposite to the adjacent protrusion 93 ( Chamfers 921 and 921 are applied to the two outer corners. Similarly, chamfers 931 and 931 are also provided at the tip of the protrusion 93 at two corners on the opposite side of the protrusion 92 from the four corners.

Although the configuration of the second support member 52 is not shown in FIG. 8, the second support member 52 also has a chamfer on the surface on the side facing the holder 81, similar to the first support member 51. A convex part 99 (FIG. 12) having two protrusions 98 is provided.
On the other hand, the holder 81 of the cleaning unit 55 is provided with two recesses 85 and 86 as shown in FIG. Specifically, the concave portion 85 is a surface 811 of the holder 81 on the side facing the first support member 51 and is provided at a position facing the convex portion 91 of the first support member 51. 81 is a surface 812 on the side facing the second support member 51, and is provided at a position facing the convex portion 99 of the second support member 52.

The concave portion 85 and the convex portion 91 have substantially the same height in the Z direction (height direction), and in the Y direction (lateral direction), the width W of the concave portion 85 and the protrusion from the outer surface 923 of the protrusion 92 are projected. 93 is substantially the same as the length L (lateral width) to the outer side surface 933 (actually, the lateral width of the recess is larger by about several hundredths of a millimeter, but for convenience of explanation, it is substantially the same. To do.)
Further, the length (depth) of the concave portion 85 in the X direction is substantially the same as the length of the convex portion 91 in the protruding direction (X direction). The relationship between the dimensions of the concave portion 85 and the convex portion 91 such as the height, width, and depth is the same for the concave portion 86 and the convex portion 99.

In such a configuration, when the cleaning unit 55 is located at the standby position, the convex portion 91 of the first support member 51 and the concave portion 85 of the holder 81 are fitted to each other, and the standby is performed by this fitting. In the position, the movement of the cleaning unit 55 in the Y direction with respect to the shield case 50 is restrained.
FIG. 10 is a diagram illustrating a state where the cleaning unit 55 is guided toward the standby position, and FIG. 11 is a diagram illustrating a state where the cleaning unit 55 is stopped at the standby position.

Here, FIG. 10A is a plan view, and FIG. 10B is a cross-sectional view taken along the line DD of FIG. 10A when the charger 2 is cut. FIG. 11A is a plan view, and FIG. 11B is a cross-sectional view taken along the line EE in FIG. 11A when the charger 2 is cut.
As shown in FIG. 10, when the cleaning portion 55 is guided toward the standby position, the convex portion 91 of the first support member 51 and the concave portion 85 of the holder 81 are separated from each other, as shown in FIG. In addition, when the cleaning unit 55 reaches the standby position, the convex portion 91 of the first support member 51 and the concave portion 85 of the holder 81 are fitted to each other. Since the chamfers 921 and 931 are provided at the tips of the projections 92 and 93, the tips of the projections 92 and 93 are easily guided inward from the opening of the recess 85, and the fitting is facilitated more smoothly. Yes. Instead of chamfering, a smoother guide can be realized by providing the protrusions 92 and 93 with a taper whose diameter decreases toward the tip.

  When the convex portion 91 and the concave portion 85 are fitted, the side surfaces of the protrusions 92 and 93 are in contact with the inner surface 813 of the concave portion 85, and the movement of the cleaning portion 55 is not restricted in the X direction. The direction along the Y direction and the Z direction is restricted, and the movement in the arrow α direction (FIG. 9), the arrow β, and the γ direction (FIG. 11) is similarly restricted. Here, the arrow α direction is an axis parallel to the X direction and corresponds to a rotation direction rotating around a virtual axis passing through the center of the cleaning unit 55. The arrow β direction is an axis parallel to the Z direction and corresponds to a rotation direction rotating around a virtual axis passing through the center of the cleaning unit 55, and the arrow γ direction is an axis parallel to the Y direction and the cleaning unit. This corresponds to the rotation direction of rotating around the virtual axis through the center of 55.

When the cleaning unit 55 moves in the direction of the arrow α, a twisting force or a force to tilt the tooth tip 531 laterally (Y direction) acts on the discharge electrode 53, and when the cleaning unit 55 moves in the arrow β direction, When the shear stress acts and moves in the direction of the arrow γ, a force acts to tilt the tooth tip 531 in the X direction.
Therefore, even if the cleaning unit 55 moves in any of the directions of arrows α to γ, there is a risk of causing deformation such as twisting of the discharge electrode 53 and bending of the tooth tip 531, but the movement is restricted. The deformation of the discharge electrode 53 at the standby position can be suppressed.

Suppression of the deformation of the discharge electrode 53 is not limited to the standby position, but can also be obtained at the return position.
FIG. 12A is a diagram illustrating a state in which the cleaning unit 55 is guided toward the return position, and FIG. 12B is a diagram illustrating a state in which the cleaning unit 55 is stopped at the return position. is there.
As shown in FIG. 12B, when the cleaning portion 55 reaches the return position, the convex portion 99 of the second support member 52 and the concave portion 86 of the holder 81 are in a mutually fitted state.

As a result, the movement of the cleaning unit 55 in the directions of the arrows α to γ is restricted even at the return position. Even if the vibration during the image forming operation is transmitted to the charger 2 when it is located at the return position, the discharge electrode 53 Deformation is suppressed.
The holder 81 is connected to the operation shaft 56 by fitting one end of the operation shaft 56 into the hook 84 and maintained in a vertical posture with respect to the shield case 50. However, depending on the dimensional tolerance of the fitting portion, the holder 81 There is a case where there is a backlash between 84 and the operation shaft 56 although it is minute. If such play is present, the holder 81 moves in an inclined posture as shown in the schematic diagram of FIG. The inclined posture is as follows.

That is, during movement in the X direction, a pulling force in the movement direction (X direction) by the operating shaft 56 acts on the holder 81 via the hook 84, and the cleaning member 82, A frictional force generated between 83 and the discharge electrode 53 acts in the direction opposite to the moving direction.
When the hook 84 on which the pulling force in the X direction acts is used as a fulcrum, the frictional force acting on the holder 81 is a force that tries to rotate the holder 81 in the direction opposite to the moving direction, and the holder 81 is the amount of play. This is because the posture becomes tilted as if tilted from the vertical posture in the direction of the arrow a where the frictional force acts. FIG. 12C shows a state in which the holder 81 is inclined in the a direction by an angle θ from the vertical posture.

When the holder 81 in the inclined posture moves in the X direction (positive direction) and reaches the position where the holder 81 is close to the second support member 52, the convex portion of the second support member 52 is formed in the concave portion 86 of the holder 81. 99 fits in.
The concave portion 86 of the holder 81 has a depth direction substantially parallel to the X direction when the holder 81 is in a vertical posture (FIG. 12A), and the convex portion 99 of the second support member 52 has a protruding direction. It is provided so as to be substantially parallel to the X direction.

  Accordingly, when the holder 81 is in an inclined posture, the depth direction of the recess 86 is inclined by an angle θ with respect to the X direction and becomes non-parallel, but the protrusion 99 of the second support member 52 and the recess 86 of the holder 81 are not parallel. Are fitted so that the orientation of the holder 86 gradually approaches a state in which the direction of the depth of the concave portion 86 is parallel to the X direction, following the direction of the convex portion 99 protruding in the X direction. The transition from the tilted posture to the vertical posture is performed (so that the angle θ decreases and approaches zero).

Each of the two protrusions 98 has a rectangular cross section like the protrusions 92 and 93, but since the tip is chamfered, the transition from the inclined posture to the vertical posture is more easily performed. ing. A taper may be provided instead of chamfering.
When the holder 81 reaches the return position, as shown in FIG. 12C, the holder 81 is in a vertical posture (angle θ is substantially 0), and the holder 81 moves in the X ′ direction (reverse direction) opposite to the X direction. When started, the attitude of the holder 81 changes from a vertical attitude to an inclined attitude that is inclined by an angle θ in the direction of the arrow b, as opposed to the normal direction.

  Thus, when there is a backlash between the hook 84 of the holder 81 and the operation shaft 56, the holder 81 is tilted by an angle θ once before and after the return of the holder 81. During the tilting operation, the discharge electrode 53 is rubbed along the γ direction by the cleaning members 82 and 83, and a force is generated to bend the tooth tip 531 of the discharge electrode 53 in the γ direction. If the force to bend is large, the discharge electrode 53 is deformed.

  For example, if a configuration in which the holder 81 and the second support member 52 are not fitted (corresponding to the prior art) is taken, the tilt angle at one time when returning from the X direction to the X ′ direction as shown in FIG. Is 2θ which is a double of the angle in the present embodiment, and the transition from the inclined posture (broken line) to the reverse inclined posture (solid line) is instantaneously performed, so that the tooth tip 531 is bent in the γ direction. The force to be applied is likely to increase, and the tooth tip 531 is easily deformed by being instantaneously applied to the tooth tip 531.

In contrast, in this embodiment, each time the holder 81 tilts, the tilt angle is as small as θ, and the concave portion 86 of the holder 81 and the convex portion 99 of the second support member 52 are tilted. Since the holder 81 gradually transitions from the inclined posture to the vertical posture when fitting, it is possible to reduce the force to bend the tooth tip 531 in the γ direction, and deformation of the discharge electrode 53 can be prevented.
In order to change the posture of the holder 81 more smoothly, it is desirable to provide the protrusion 98 with a taper whose diameter decreases toward the tip as described above. In addition to the transition from the tilt posture immediately before the return to the vertical posture, the transition is performed more smoothly when the vertical posture immediately after the return transitions to the reverse tilt posture. This is the same for the protrusions 92 and 93 in the first support member 51.

As described above, in the present embodiment, the convex portion 91 of the first support member 51 and the concave portion 85 of the holder 81 are fitted in the standby position, and the convex portion 99 of the second support member 52 is in the return position. The concave portion 86 of the holder 81 is configured to be fitted, and the holder 81 is held by the shield case 50 via the first and second support members 51 and 52 when fitted.
Therefore, when vibration during the image forming operation is transmitted to the charger 2, the holder 81, the shield case 50, and the discharge electrode 53 come to vibrate together, and the discharge electrode 53 of the holder 81 is vibrated. A force for bending the tooth tip 531 to the side does not act, and deformation of the discharge electrode 53 such as twisting of the discharge electrode 53 and bending of the tooth tip 531 can be suppressed.

In the above description, the lateral width (convex width) L of the convex portion 91 provided on the first support member 51 and the lateral width (concave width) W of the concave portion 85 provided on the holder 81 are substantially the same. Although the example of a structure was demonstrated, it is not restricted to this.
For example, before the first support member 51 is attached to the shield case 50, the width L of the convex portion is set to be slightly wider than the width W of the concave portion. After being attached to the case 50, a force is applied to the convex portion 91 in the direction in which the lateral width becomes narrower, and the width L of the convex portion becomes substantially the same as the width W of the concave portion. Is also possible. Hereinafter, this configuration example will be described with reference to FIG.

FIG. 13 shows a cut when the outer surfaces 923, 933 of the projections 92, 93 of the first support member 51 are provided on the bottom plate 73 of the shield case 50 when the first support member 51 is attached to the shield case 50. It is a figure which shows the mode before and behind the mounting | wearing at the time of fitting to the notch 77, and shows the front view before mounting | wearing, and has shown the front view and top view after mounting | wearing together.
The shield case 50 is shown in a cross-sectional view taken along the line BB in FIG. 7, and the notch 77 of the shield case 50 is a long hole of the shield case 50 as shown in FIG. 74 is extended to the rear side of the apparatus, and the length in the Y direction is F.

As shown in FIG. 13, the length in the Y direction (the width of the convex portion) from the outer surface 923 of the protrusion 92 to the outer surface 933 of the protrusion 93 provided on the first support member 51 is the first support member. G (> F) before the 51 is attached to the shield case 50, and substantially the same as F after the attachment.
When the projections 92 and 93 of the first support member 51 made of resin are press-fitted into the notch 77 having a length shorter than G, the direction in which the projections 92 and 93 are brought closer to each other from the bottom plate 73 of the shield case 50 (the width is narrowed). (Direction), the projections 92 and 93 bend in that direction, and the width of the convex portion is reduced from G to F.

Thus, the width | variety of a convex part is taken in the process of mounting | wearing the shield case 50 with the 1st support member 51 and the cleaning part 55 by taking the structure which is shrunk before and after mounting | wearing with the shield case 50 of the 1st support member 51. Work efficiency can be improved.
That is, the width of the protrusion is set slightly wider than the width W of the recess (FIG. 4) within a range in which the protrusions 92 and 93 can be fitted into the recess 85 of the holder 81 before mounting. If the projections 92 and 93 are fitted into the recesses 85 of the holder 81, the projections 92 and 93 are pressed into the recesses 85 due to the restoring force of the bent projections 92 and 93. , Both can be brought into a state of being pulled with a certain degree of strength.

If the first support member 51 and the holder 81 (cleaning unit 55) can be integrally pulled before mounting, for example, in the manufacturing process of the charger 2, the shield case of the first support member 51 In the mounting process to 50, mounting can be performed in a state where the first support member 51 and the cleaning unit 55 are integrated.
After the first support member 51 is attached to the shield case 50, the width of the convex portion is reduced from G to F as described above, so that the press-fitted state of the projections 92 and 93 into the concave portion 85 of the holder 81 is eliminated. Is done. If the width W of the recess is set to be approximately the same as F, the protrusion 91 and the recess 85 can be smoothly fitted after mounting.

Then, when the fitting between the two is released and the holder 81 is moved in the X direction, the constricted portion 89 of the holder 81 can be easily fitted into the long hole 74 of the shield case 50.
If such a process is performed, for example, compared with the process of attaching and fitting the first support member 51 and the cleaning unit 55 to the shield case 50 separately, the total man-hours can be reduced and the assembly work efficiency can be reduced. Can be improved.

  The width G of the convex portion, the width W of the concave portion, and the length F of the notch are, for example, G = 4.00 [mm], W = 3.94 [mm], F = 3.91 [mm]. Needless to say, but not limited to this. Before the first support member 51 is attached to the shield case 50, the first support member 51 and the cleaning portion 55 are in a state of being fitted with a force that does not immediately come off. A suitable size, shape, material, and the like for the convex portion 91, the concave portion 85, and the cutout 77 are determined in advance from experiments so that the fitting is released by movement in the X direction.

<Modification>
Needless to say, the technical scope of the present invention is not limited to the above embodiment, and for example, the following modifications can be considered.
(1) In the above embodiment, the convex portion 91 of the first support member 51 has the two protrusions 92 and 93, but the present invention is not limited to this. Any shape that fits into the concave portion 85 of the holder 81 may be used, and for example, one or three or more protrusions may be used as the convex portion.

Further, in the above embodiment, the first and second support members 51 and 52 are provided with the convex portions 91 and 99, and the surface 811 of the holder 81 facing the first support member 51 and the second support member 52. The concave portions 85 and 86 are provided on the surface 812 facing the surface.
If this structure is taken, it is not necessary to provide a convex part on the holder 81 side. Therefore, as shown in FIG. 11, when the holder 81 is in the standby position, the surface 812 of the holder 81 is in the X direction (the axial direction of the photosensitive drum 1: corresponding to the main scanning direction) other than the image forming area. The first support member 51 can be attached to the shield case 50 so as to be close to the image forming area so that it is located at the border between the non-image forming area and the image forming area, and charged in the main scanning direction. The length of the device 2 can be shortened to reduce the size of the entire apparatus.

  In addition, although the structure which provides a convex part in the holder 81 side can also be taken, a convex part protrudes in the image formation area side from the surface 812 of the holder 81 in a stand-by position, and a convex part enters into an image formation area. Even if the convex portion of the holder 81 enters the image forming area, the convex portion of the holder 81 does not directly affect the corona discharge from the discharge electrode 53, but the intensity distribution of the electric field in the shield case 50 is as follows. Some change due to the presence of the protrusions. If the change in the electric field intensity distribution affects the charge distribution of the photoconductive drum 1, the surface potential of the photoconductive drum 1 may become non-uniform in the main scanning direction, leading to uneven charging.

  In order to avoid the occurrence of such charging unevenness, the position of the first support member 51 should be away from the image forming area in the main scanning direction so that the convex portion of the holder 81 does not enter the image forming area. When the first support member 51 is moved away from the image forming area, the length of the charger 2 becomes longer in the main scanning direction. Therefore, it can be said that a configuration in which a concave portion is provided on the holder 81 side is preferable in view of downsizing of the apparatus. Of course, a configuration may be adopted in which a convex portion is provided on the holder 81 side when there is a certain margin in the main scanning direction or for the convenience of the apparatus configuration. It is also possible to adopt a configuration in which a convex portion is provided on the surface 811 on the first support member 51 side of the holder 81 and a concave portion is provided on the surface 812 on the second support member 52 side.

(2) In the above embodiment, the convex portions are provided on both the first support member 51 and the second support member 52. However, the present invention is not limited to this. For example, only the standby position side is provided. It may be taken.
(3) In the above-described embodiment, the configuration example in which a sawtooth-shaped electrode is used as the discharge electrode 53 that performs corona discharge for charging the photosensitive drum 1 is described, but the configuration is not limited thereto. The discharge electrode may be long as long as it has a plurality of sharp protrusions arranged in the longitudinal direction. For example, a pin shape in which a plurality of pins are arranged at intervals. The present invention can also be applied to a configuration using the discharge electrode.

  (4) The shape, size, material, and the like of the shield case 50, the first and second support members 51 and 52, the discharge electrode 53, the holder 81, and the cleaning members 82 and 83 in the above embodiment are the same as those described above. Needless to say, a shape, size, or the like suitable for the device configuration is used. Further, the convex portion has a rectangular cross section, but is not limited thereto, and may be, for example, a cylindrical shape or a polygonal shape. In this case, the recess is formed in a shape that fits into the protrusion.

Note that when a cylindrical convex portion is used, if only one convex portion is provided, the concave portion also has a circular cross section, and rotation around the axis of the cylindrical convex portion is allowed, so that the holder 81 is α Since there is a risk of moving in the direction, it is desirable to adopt a configuration in which a plurality of convex portions are provided.
(5) In the above embodiment, the first support member 51 and the holder 81 are provided with a convex portion and a concave portion, and the convex portion and the concave portion are fitted. However, the present invention is not limited to this. Any configuration may be used as long as it is provided with a shift regulating means for regulating the shift of the holder 81 in a direction in which at least the tooth tip 531 of the discharge electrode 53 is bent.

  For example, the first support member 51 and the holder 81 can be configured such that one is a groove and the other is a pin, and the pin is inserted into the groove. In this case, when the groove portion is provided along the Z direction (the direction toward the photosensitive drum 1), the holder 81 is caused to change (movement) in at least the Y direction (the direction in which the tooth tip 531 is bent sideways). Can be regulated. Of the grooves or pins, the one provided on the first support member 51 side is the transition restricting means.

Moreover, it is not restricted to the structure which the 1st supporting member 51 and the holder 81 engage.
For example, a configuration in which a member attracted by a magnet is attached to the holder 81, and a magnet is arranged as a displacement restricting unit on the first support member 51, so that the holder 81 is prevented from being displaced by the magnetic force of the magnet at the standby position. Conceivable. In the case of this configuration, the holder 81 and the transition restricting means can be brought into non-contact. Each of the above examples is applicable to the second support member 52.

  (6) In the above-described embodiment, a configuration example in which the charging device according to the present invention is applied to the charger 2 that charges the photosensitive drum 1 as an example of the image carrier of the image forming apparatus as the member to be charged will be described. However, it is not limited to this. The present invention can be applied to a general charging device for charging an object to be charged provided in an image forming apparatus. For example, the member to be charged may be applied to a charging device that charges the intermediate transfer belt 21 as the intermediate transfer belt 21 which is another example of the image carrier.

  Further, in the above, the cleaning portion 55 (holder 81) is guided in a movable manner in the region between the first support member 51 and the second support member 52 in the longitudinal direction of the discharge electrode 53. The position at one end in the longitudinal direction within the region (the position at which the first support member 51 is full) is set as the standby position of the holder 81, but the position at the other end or each of the both ends may be set as the standby position. A shift restricting means for the holder 81 is provided at the position where it becomes the standby position.

Furthermore, the standby position is not limited to the position at one end or both ends in the longitudinal direction within the above-described region. For example, an area of a certain size such as a non-image forming area that does not affect the charging of the object to be charged is provided in the movable area of the holder 81 between the first support member 51 and the second support member 52. If there is, a position other than the end portion in the longitudinal direction in the region may be set as the standby position.
Further, a long hole 74 is provided in the bottom plate 73 of the shield case 50, a constricted portion 891 having a width slightly narrower than the width of the long hole 74 is provided as a guide piece on the holder 81 of the cleaning portion 55, and the constricted portion 891 is formed into the long hole 74. Although the holder 81 is guided so as to be movable in the longitudinal direction by being fitted in, it is not limited thereto. The holder 81 may be configured to guide the holder 81 along the shield case 50 in the longitudinal direction of the discharge electrode 53. For example, the side plates 71 and 72 of the shield case 50 are provided with long holes, and the holder 81 is provided in the long holes. The present invention can also be applied to a configuration in which the guide piece is fitted and supported so as to be movable.

  Further, the contents of the above embodiment and the above modification may be combined.

  The present invention can be widely applied to charging devices that charge a charged object such as an image carrier provided in an image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charger 50 Shield case 51 1st support member 52 2nd support member 53 Discharge electrode 55 Cleaning part 56 Operation shaft 71, 72 Side plate of a shield case 73 Bottom plate of a shield case 74 Long hole of a shield case 78 Opening 81 Holder 82, 83 Cleaning member 84 Hook 85, 86 Concave portion 89 Constricted portion 91, 99 Convex portion 92, 93, 98 Protrusion 531 Discharged sawtooth tip 532 Discharge electrode side surface 811 First support member in holder 812 Face of the holder facing the second support member 921, 931 Chamfer M1 Wide part of the long hole of the shield case M2 Narrow part of the long hole of the shield case R1 Width of the constricted part R2 Width of the hook R3 Holder Bottom width of

Claims (10)

A charging device for charging the surface of an object to be charged provided in an image forming apparatus,
A long electrode for performing corona discharge for charging the object to be charged, wherein a plurality of sharp protrusions are arranged in the longitudinal direction, and the tip of the protrusion is the object to be charged A discharge electrode arranged to face
A cleaning member for cleaning the discharge electrode;
A holder for holding the cleaning member in contact with the discharge electrode;
Guiding means for guiding the holder in the longitudinal direction of the discharge electrode starting from a standby position;
When the holder is in the standby position, a transition restricting means for restricting the transition of the holder in a direction in which at least the tip of the protrusion of the discharge electrode is bent,
A charging device comprising: A first support member and a second support member that respectively support the longitudinal ends of the discharge electrode;
The guide means guides the holder movably in a region between the first support member and the second support member,
The standby position is a position of one end or both ends in the longitudinal direction in the region,
The holder is provided with a first convex portion or a first concave portion at a portion facing at least one of the first support member and the second support member,
The transition regulation means is
Inserted in the second concave portion or the first concave portion in which the first convex portion is inserted, which is provided on at least one of the first support member and the second support member. The charging device according to claim 1, wherein the charging device is a second convex portion. The holder is provided with the first concave portion;
The charging device according to claim 2, wherein the second convex portion is provided on the support member side.   The charging device according to claim 2, wherein a cross-sectional shape of the convex portion is a polygon.   5. The charging device according to claim 2, wherein the convex portion includes a pair of protrusions arranged side by side in the thickness direction of the discharge electrode.   The charging device according to claim 5, wherein the tip of the protrusion is provided with a taper whose diameter decreases toward the tip. The discharge electrode is long in the longitudinal direction, and includes a shield case that surrounds the discharge electrode and is open at a surface facing the charged body.
The first support member is attached to one end in the longitudinal direction of the shield case,
The second support member is attached to the other end in the longitudinal direction of the shield case,
The holder is located in the shield case;
The guide means includes a guide piece provided in the holder and a long hole provided in the shield case along the longitudinal direction and into which the guide piece of the holder is fitted. 7. The charging device according to any one of 6 above. The long hole is provided in a bottom portion facing the opening of the shield case,
When the long hole is divided into both end portions and the central portion in the longitudinal direction, assuming that the width of at least one end portion is M1 and the width of the central portion is M2, the relationship is M2 <M1.
The guide piece is provided at a bottom portion of the holder facing the long hole,
The tip of the guide piece protrudes outside the shield case through the long hole,
A narrow constricted portion in the width direction is provided at a portion where the holder and the guide piece are connected, the width direction length of the constricted portion is R1, and the width length of the guide piece is 8. The charging device according to claim 7, wherein a relationship of R1 <M2 <R2 <M1 <R3 is satisfied, where R2 is a thickness and R3 is the length in the width direction of the bottom of the holder. The discharge electrode is long in the longitudinal direction, and includes a shield case that surrounds the discharge electrode and is open at a surface facing the charged body.
The first support member is attached to one end in the longitudinal direction of the shield case,
The second support member is attached to the other end in the longitudinal direction of the shield case,
The holder is located in the shield case;
The convex portions are provided on a surface of the first support member facing the holder, and have first and second flexible members arranged side by side in the thickness direction of the discharge electrode. With two protrusions,
The shield case has a notch into which the bottom of each of the first and second protrusions provided on the first support member is fitted at a position where the first support member is mounted;
The first protrusion of the second protrusion from the first surface of the first protrusion opposite to the surface facing the second protrusion before the first support member is attached to the shield case. When the width of the protrusion up to the second surface opposite to the surface opposite to the first surface is the first value,
After being mounted, the first and second protrusions are fitted into the notches during mounting, and the first and second protrusions are deflected by forces acting on each other to approach each other. The charging device according to claim 3, wherein the width of the protrusion is configured to be a second value that is narrower than the first value. An image forming apparatus provided with a charging means for charging the surface of an object to be charged for image formation,
An image forming apparatus comprising the charging device according to claim 1 as the charging unit.

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