JP4077164B2 - Charging device and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a charging device.And image forming apparatusMore particularly, the present invention relates to a non-contact roller charging device suitable for use in an image forming apparatus such as a printer, a facsimile machine, and a copying machine.
[0002]
[Prior art]
A conventional charging device of this type is a contact type. For example, in the charging roller and the charging device disclosed in Japanese Patent Application Laid-Open No. 6-348110, an elastic body layer and a surface layer containing pressure-sensitive conductive rubber are laminated on a core metal, and the pressure is adjusted for a long time. The charged member (photosensitive member) can be uniformly charged to a desired charging voltage.
[0003]
In the contact charging system as described above, consideration is given to uniform stabilization of the charging potential. However, foreign matters remaining on the surface of the photosensitive member, which is a member to be charged (remaining toner components that could not be removed by cleaning, , Paper constituents such as paper dust, talc, etc.) are unavoidably stuck to the charging roller, and charging unevenness occurs over time, resulting in a short lifespan. The commercialization of the required class of electrophotographic copying machines has not been realized. In order to solve this problem, a non-contact roller charging device using a non-contact charging roller has been studied.
[0004]
[Problems to be solved by the invention]
However, using a non-contact roller charging device to apply an applied voltage of about 800 V and perform stable and stable photoconductor charging, the gap (air gap) between the charging roller and the member to be charged is 10 μm to 50 μm. Must be kept. As a technique that makes this possible, for example, there is a technique described in Japanese Utility Model Laid-Open No. 5-15057. In this technique, ring-shaped elastic spacer members are mounted on the circumferential portions (both ends circumferential portions) on both sides of the member to be charged so as to maintain the gap between the charging roller and the member to be charged. However, in this method, unless the variation in the circumferential thickness of the ring-shaped elastic spacer member is set to 30 μm or less, uneven charging due to the variation in the gap occurs in one rotation cycle of the member to be charged.
[0005]
In the technique described in Japanese Patent Application Laid-Open No. 9-31526, as a method for maintaining the gap between the charging roller and the member to be charged, a spacer roller is disposed at the shaft end of the charging roller and the spacer roller is abutted against the member to be charged. The gap is set at half the difference between the diameter of the spacer roller and the charging roller. Otherwise, it is difficult to make the variation in the gap of one rotation of the charging roller 30 μm or less, resulting in uneven charging due to the variation in the gap of the charging roller.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate uneven charging due to fluctuations in the gap between the charging rollers so that the minute gap between the charging roller and the member to be charged can be kept constant in the non-contact roller charging device. And
[0007]
[Means for Solving the Problems]
  In order to solve the above-described problems and achieve the above object, the invention described in each claim employs the following characteristic means.
  According to a first aspect of the present invention, there is provided a charging device for charging a member to be charged by keeping the rotating charging roller in a non-contact state with the member to be charged, and both ends of the charging roller and both ends of the member to be charged. Sandwiched betweenEngulfed,Low friction resistance spacer member having a thickness capable of maintaining the non-contact stateAnd variable means for changing the position of the contact portion of the spacer member that contacts both ends of the charging roller and both ends of the charged body, and the spacer member has a certain thickness, The variable means is a moving mechanism that moves the spacer member along the rotation direction of the charging roller.It is characterized by that.
[0008]
  The invention according to claim 2The rotating charging roller is kept in a non-contact state with the object to be charged to charge the object to be charged.In the charging device,A spacer member having a low frictional resistance having a thickness capable of maintaining the non-contact state between the both ends of the charging roller and the both ends of the member to be charged, both ends of the charging roller, and And a variable means for changing the position of the contact portion of the spacer member that contacts both ends of the charged body, and the spacer member is a belt-like spacer member having a flexible belt-like shape. The variable means is a winding mechanism for winding the belt-shaped spacer member.It is characterized by that.
[0009]
  The invention described in claim 3The rotating charging roller is kept in a non-contact state with the object to be charged to charge the object to be charged.In the charging device,A low frictional resistance spacer member sandwiched between both ends of the charging roller and both ends of the charged body and having a thickness capable of maintaining the non-contact state;Variable means for changing the position of the contact portion of the spacer member that contacts both ends of the charging roller and both ends of the member to be charged;And the spacer member is a rotatable disc-like spacer member having a disc-like shape, and the variable means is a rotating mechanism for rotating the disc-like spacer member.It is characterized by that.
[0010]
  The invention according to claim 4 is the claim of claimAny one of 1 to 3In the charging device described,The spacer member is made of a fluororesin material.It is characterized by that.
[0011]
  The invention according to claim 5An image forming apparatus comprising the charging device according to claim 1.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention including examples will be described with reference to the drawings (hereinafter simply referred to as “embodiments”). In each embodiment, members, components, and the like having the same function and shape are denoted by the same reference numerals and description thereof is omitted. In the drawing, members and components that are configured as a pair and do not need to be specifically distinguished and described are described by appropriately describing one of them in order to simplify the description. In addition, in order to simplify the drawings and the description, even members and components that are to be represented in the drawings may be omitted without any notice unless necessary. .
[0015]
First, with reference to FIG. 1, the technical matter common to embodiment mentioned later is demonstrated. These common technical matters will not be described in the embodiments described later.
In FIG. 1, reference numeral 1 denotes a charging roller, reference numeral 2 denotes a photosensitive member as an example of an object to be charged, reference numeral 3 denotes a charging roller power source (hereinafter simply referred to as “power source 3”), and reference numeral 4 denotes an electrostatic latent. Reference numeral 5 denotes a developing device, reference numeral 6 denotes a transfer unit, reference numeral 7 denotes a charge eliminating / separating unit, and reference numeral 8 denotes a transfer sheet as a transfer material. In FIG. 2 to FIG. 8 showing each embodiment to be described later, the charging roller 1 and the photosensitive member 2 are simply shown for the sake of simplification of the drawing.
[0016]
The charging roller 1 is supported at both ends of the core shaft 1c by a bearing (not shown), and can be rotated counterclockwise as indicated by an arrow in FIG. 1 by a driving mechanism (not shown) (see FIG. 6 described later). Yes. The charging roller 1 charges the outer peripheral surface of the photosensitive member 2 while being kept in a non-contact state with the outer peripheral surface of the photosensitive member 2 by a spacer member of each embodiment described later. The charging roller 1 is pressed with a constant pressure by a pressure mechanism (not shown) in a direction in which the spacer member is sandwiched and pressed against the photoconductor 2 (see, for example, a pressure mechanism 29 in FIG. 8 described later).
[0017]
The charging roller 1 includes a middle to high resistance layer portion 1a (hereinafter simply referred to as “high resistance layer portion 1a”), an inner periphery low resistance layer portion 1b, and an innermost core shaft 1c. Become. The high resistance layer portion 1a has a resistance value ρ1 (Ω · cm) of ρ1> 10.^FiveIt is preferable that the thickness of the thinnest layer is 0 to 10 μm. The low resistance layer portion 1b has a resistance value ρ2 (Ω · cm) of ρ2 <ρ1. In addition, since the voltage application from the power supply 3 is performed with respect to the core shaft 1c, a conductive metal is used for the core shaft 1c.
[0018]
When the photosensitive member 2 is charged, the voltage of the air gap or gap (air gap) between the surface of the high resistance layer portion 1a forming the outer peripheral surface of the charging roller 1 and the outer peripheral surface of the photosensitive member 2 is the air breakdown voltage. A voltage is applied by the power source 3 so as to exceed the range.
In order to perform stable charging of the photosensitive member without unevenness, the outer peripheral surface of the charging roller 1 (hereinafter simply referred to as “charging roller 1”) and the outer peripheral surface of the photosensitive member 2 (hereinafter simply referred to as “photosensitive member 2”). It is better to set the gap G to 6 to 48 μm and the applied voltage to around 800V.
[0019]
The photoreceptor 2 is supported at both ends of the shaft by a bearing (not shown), and is rotated in the clockwise direction indicated by an arrow in FIG. 1 by a driving mechanism (not shown) (see FIG. 6 described later).
[0020]
  The charging device shown in FIG. 1 has a gap between both ends of the charging roller 1 (front side and back side of the paper in FIG. 1) and both ends of the photosensitive member 2 (front side and back side of the paper in FIG. 1). Charging is performed in such a manner that a low friction resistance spacer member having a thickness capable of maintaining a non-contact state, that is, a thickness capable of maintaining a gap G within a predetermined range is sandwiched.
  Therefore, according to the charging device shown in FIG. 1, the advantages common to first to fifth described later, that is, the minute gap G between the charging roller 1 and the photosensitive member 2 can be maintained constant, and the charging roller There is an advantage that uneven charging due to fluctuations in the gap of 1 can be eliminated.
(First embodiment)
  2 and 3 show the first embodiment.The
  As shown in FIGS. 2 and 3, a spacer member 10 having a thickness of 10 to 50 μm is sandwiched between both ends of the charging roller 1 and both ends of the photosensitive member 2, and is fixed to the apparatus main body side. The spacer member 10 is fixed by the spacer support member 11 so as not to move due to the rotation of the charging roller 1. The spacer member 10 is a thin plate-like member.
  One end of the spacer member 10 is fixed to the left spacer support member 11 in FIG. 2, and the other end is between one end of the charging roller 1 and one end of the photosensitive member 2 and the other end of the charging roller 1. And the other end of the photosensitive member 2, that is, between the both ends of the charging roller 1 and the two ends of the photosensitive member 2.
[0021]
The charging roller 1 is supported at both ends of the core shaft 1c by a bearing (not shown), and can be rotated in a counterclockwise direction indicated by an arrow in FIG. 1 by a driving mechanism (not shown) (see FIG. 6 described later). ing. The charging roller 1 is pressed at a constant pressure by a pressure mechanism (not shown) in a direction in which the spacer member 10 is sandwiched and pressed against the photoconductor 2 (see, for example, a pressure mechanism 29 in FIG. 8 described later). The photoreceptor 2 is supported at both ends of its shaft by a bearing (not shown), and is rotated in a clockwise direction indicated by an arrow in FIG. 1 by a driving mechanism (not shown) (see FIG. 6 described later).
[0022]
In the first embodiment, as described above, the low frictional resistance spacer member 10 having a thickness capable of holding the gap G in a predetermined range is sandwiched between the both ends of the charging roller 1 and the photoreceptor 2. As a result, a gap G of 10 to 50 μm is formed between the charging roller 1 and the photosensitive member 2. Therefore, according to the first embodiment, there is no fluctuation of the gap G due to one rotation period of the charging roller 1 while maintaining a constant gap G. Further, there is an advantage that gap variation due to machining accuracy can be minimized.
[0023]
Here, the material of the spacer member 10 is sandwiched between both ends of the charging roller 1 and both ends of the photosensitive member 2, and is in contact with both ends of the charging roller 1 and both ends of the photosensitive member 2. In order to reduce the frictional resistance as much as possible to reduce its rotational resistance and wear, it is preferable to form it with a low frictional resistance fluororesin. The same applies to the spacer members of the second to fifth embodiments described later.
Examples of the fluororesin material include polytetrafluoroethylene (PTFE), tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymer. A polymer (ETFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF) and the like are preferably used.
[0024]
  The spacer member 10 may be formed of an appropriate low-friction-resistant resin other than the low-friction-resistant fluororesin, as long as the advantages as described above are not desired.Yes.
(Second Embodiment)
  FIG. 4 shows the second embodiment.The
  Compared to the first embodiment, the second embodiment has a movable spacer support member 11A instead of the spacer support member 11 fixed on the apparatus main body side in the first embodiment. And a moving mechanism for moving the spacer member 10 along the rotation direction of the charging roller 1 as a variable means for changing the position of the contact portion of the spacer member 10 that contacts both ends of the charging roller 1 and both ends of the photosensitive member 2. Is mainly different.
[0025]
As shown in FIG. 4, the other end portion of the spacer member 10 having a constant thickness of 10 to 50 μm is sandwiched between both end portions of the charging roller 1 and the photoreceptor 2, and the spacer is supported by the spacer support member 11A. The member 10 is fixed so as not to move due to the rotation of the charging roller 2.
[0026]
On one end portion side of the spacer support member 11A, a moving mechanism configured by a rack 12 and a pinion 13 meshing with the rack 12 is disposed so as to move the spacer support member 11A horizontally along the rotation direction of the charging roller 2. ing. The pinion 13 is rotatably supported in a clockwise direction indicated by an arrow in FIG. 4 at a fixed position on the apparatus main body side via a bearing (not shown). By the moving mechanism, the spacer member 10 together with the spacer support member 11 </ b> A is sent out horizontally in a constant amount along the rotation direction of the charging roller 2.
[0027]
For example, when the pinion 13 is connected to the output shaft of an electric motor 13A fixed on the apparatus body side, and the electric motor 13A wears and decreases due to a command from a control device (not shown). You may comprise so that it may be rotationally driven. Then, a detecting means for detecting indirectly or directly that the thickness of the spacer member 10 has been worn and reduced is appropriately disposed, and the control device detects the spacer member based on an output signal from the detecting means. The electric motor 13 </ b> A may be controlled so as to adjust the 10 movement amount.
In addition, if the moving mechanism of 2nd Embodiment does not need the above-mentioned advantage by electricity, it is also conceivable that the handle attached to the pinion 13 is manually rotated and adjusted, for example.
[0028]
The charging roller 1 sandwiches the other end portion of the spacer member 10 and is pressurized with a constant pressure by a pressure mechanism (not shown) in a direction in which the charge roller 1 is pressed against the photosensitive member 2 (see, for example, a pressure mechanism 29 in FIG. 8 described later). ). The charging roller 1 is supported at both ends of the core shaft 1c by a bearing (not shown), and can be rotated in a counterclockwise direction indicated by an arrow in FIG. 4 by a driving mechanism (not shown) (see FIG. 6 described later). ing. The photosensitive member 2 is supported at both ends of its shaft by a bearing (not shown), and is rotated in a clockwise direction indicated by an arrow in FIG. 4 by a driving mechanism (not shown) (see FIG. 6 described later).
[0029]
  According to the second embodiment, since the moving mechanism is provided, even if the thickness of the spacer member 10 is reduced due to wear, the reduction of the thickness of the spacer member 10 is restored by sending out a new spacer member 10. A decrease in the gap G between the charging roller 1 and the photosensitive member 2 can be eliminated.
(Third embodiment)
  FIG. 5 shows a third embodiment.The
  Compared to the first embodiment, the third embodiment replaces the spacer member 10 fixed on the apparatus main body side with a belt-shaped spacer member 10A (hereinafter referred to as a belt-shaped spacer member having flexibility). The spacer member 10A as a variable means for changing the position of the contact portion of the spacer member 10A that contacts the both ends of the charging roller 1 and the both ends of the photoreceptor 2. The main difference is that it has a winding mechanism.
[0030]
As shown in FIG. 5, a spacer member 10 </ b> A having a thickness of 10 to 50 μm is sandwiched between both ends of the charging roller 1 and the photoreceptor 2, and moves horizontally in the rotation direction of the charging roller 1. A feeding mechanism 14 for feeding the spacer member 10A and a winding mechanism 15 for winding the fed spacer member 10A are provided. The spacer member 10A is made of the above-described fluororesin material having a predetermined flexibility, and the spacer member 10A is fed out by the feeding mechanism 14, and the used spacer member 10A is wound into a roll shape by the winding mechanism 15. It has come to be taken. The winding mechanism includes a feeding mechanism 14 and a winding mechanism 15.
[0031]
The delivery mechanism 14 is detachable with respect to the apparatus main body side, locks one end of the spacer member 10A, winds the spacer member 10A in a roll shape, and rotates in a clockwise direction indicated by an arrow in FIG. A flexible feed shaft 14A and a support member (not shown) provided on the apparatus main body side that rotatably supports the feed shaft 14A.
The winding mechanism 15 is detachable with respect to the apparatus main body side, locks the other end of the spacer member 10A, and can rotate in a clockwise direction indicated by an arrow in FIG. A support member (not shown) provided on the apparatus main body side that rotatably supports the winding shaft 15A, and an electric motor 15B that rotates the winding shaft 15A in the clockwise direction.
[0032]
In this way, the delivery shaft 14A and the take-up shaft 15A are configured as a kind of spacer member storage cassette connected via the spacer member 10A, and the spacer member storage cassette is attached to and detached from the apparatus main body side. Also good.
[0033]
The electric motor 15B is configured to be driven to rotate when the thickness of the spacer member 10A is reduced by wear according to a command from a control device (not shown). A detecting means for detecting indirectly or directly that the thickness of the spacer member 10A has decreased due to wear is appropriately disposed. Based on an output signal from the detecting means, the controller controls the spacer member 10A. The electric motor 15B may be controlled so as to adjust the feed amount.
In addition, if the moving mechanism of the third embodiment does not need the above-described advantages by electric power, for example, it is conceivable to manually rotate and adjust a handle attached to the winding shaft 15A.
[0034]
The charging roller 1 is pressed with a constant pressure by a pressure mechanism (not shown) in a direction in which the spacer member 10A is sandwiched and pressed against the photoreceptor 2 (see, for example, a pressure mechanism 29 in FIG. 8 described later). The charging roller 1 is supported at both ends of the core shaft 1c by a bearing (not shown), and can be rotated in a counterclockwise direction indicated by an arrow in FIG. 5 by a driving mechanism (not shown) (see FIG. 6 described later). ing. The photoreceptor 2 is supported at both ends of its shaft by a bearing (not shown), and is rotated in the clockwise direction indicated by an arrow in FIG. 5 by a driving mechanism (not shown) (see FIG. 6 described later).
[0035]
  According to the third embodiment, even if the thickness of the spacer member 10A is reduced due to wear, the reduction in the thickness of the spacer member 10A is restored by sending out a new spacer member 10A. The decrease in the gap G can be eliminated. In addition, since the amount of the spacer member 10A delivered increases, there is an advantage that the time for maintaining the gap G constant increases.
(Fourth embodiment)
  6 and 7 show a fourth embodiment.The
  Compared to the first embodiment, the fourth embodiment replaces the spacer member 10 fixed to the apparatus main body side, and is a rotatable disk-shaped spacer member 16 (hereinafter simply referred to as “ Rotation of rotating the spacer member 16 as a variable means for changing the position of the abutting portion of the spacer member 16 in contact with both ends of the charging roller 1 and both ends of the photosensitive member 2. The main difference is that the mechanism 31 is provided.
[0036]
A disc-shaped spacer member 16 having a thickness of 10 to 50 μm and a constant thickness is sandwiched between both ends of the charging roller 1 and the photoreceptor 2. The spacer member 16 is formed in a circular plate shape from the above-described fluororesin material.
[0037]
As shown in FIGS. 6 and 7, the rotation mechanism 31 includes a rotation shaft 20 that passes through the spacer member 16 and is attached to the rotation center thereof, a bearing 19 provided at one upper end of the rotation shaft 20, An apparatus main body having a driven gear 17B provided at the lower end of the other end of the shaft 20, an idle gear 17A that meshes with the driven gear 17B, a drive gear 17 that always meshes with the idle gear 17A, and the drive gear 17 as an output shaft. It is mainly comprised from the disk-shaped spacer member drive motor 18 fixed by the side. The idle gear 17A is rotatably supported and disposed on the apparatus main body side via a bearing (not shown).
[0038]
Each spacer member 16 is rotatably supported by a bearing 19 via a rotating shaft 20 so that the upper and lower surfaces of each spacer member 16 are perpendicular to the outer peripheral buses of the charging roller 1 and the photoreceptor 2. Are arranged symmetrically at both ends of the charging roller 1. Disc-shaped spacer members 16 are disposed at both end portions of the charging roller 1. Accordingly, the rotation mechanism 31 is also arranged symmetrically on both sides of the charging roller 1. As shown in FIG. 7, the left and right disc-like spacer member driving motors 18 shown in FIG.
[0039]
As shown in FIG. 6, the driving mechanism of the charging roller 1 includes a pair of left and right bearings 23 and 23 that rotatably support the core shaft 1c at both ends of the charging roller 1, and the core shaft 1c of the charging roller 1 shown in FIG. In FIG. 2, the driven gear 22A fixed at the right end, the drive gear 22 meshing with the driven gear 22A, and the charging roller drive motor 21 having the drive gear 22 as an output shaft are mainly configured.
As described above, the charging roller 1 is rotationally driven by the charging roller driving motor 21 of the driving mechanism.
[0040]
On the other hand, as shown in FIG. 6, the driving mechanism of the photosensitive member 2 includes a pair of left and right bearings 24 and 24 for rotatably supporting the shafts at both ends of the photosensitive member 2, and the right side of the shaft of the photosensitive member 2 in FIG. A driven pulley 25A fixed at the end, a drive pulley 25 provided on the apparatus main body side in the vicinity of the driven pulley 25, a belt 25B spanned between the driven pulley 25A and the drive pulley 25, and a drive It is mainly composed of a photoreceptor driving motor 26 having a pulley 25 as an output shaft and fixed on the apparatus main body side. As described above, the photoreceptor 2 is rotationally driven by the photoreceptor drive motor 26 of the drive mechanism.
[0041]
  According to the fourth embodiment, by having the disc-shaped spacer member 16 having a constant thickness, the disc-shaped spacer member driving motor 18 of the rotating mechanism is driven even if the thickness of the spacer member 16 decreases due to wear. Then, by rotating the spacer member 16 to bring out the contact portion of the new spacer member 16, the reduction in the thickness of the spacer member 16 is restored, so that the reduction in the gap G between the charging roller 1 and the photosensitive member 2 is eliminated. There is an advantage that can be.
(Reference example)
  Figure 8Reference exampleShowThe
  Reference example shown in FIG.Compared with the first embodiment, instead of the spacer member 10 fixed on the apparatus main body side, a wedge-shaped spacer member 27 having a wedge-shaped shape whose thickness changes along the rotation direction of the charging roller 1. (Hereinafter simply referred to as "spacer member 27"), and a spacer member as a variable means for changing the position of the contact portion of the spacer member 27 that contacts both ends of the charging roller 1 and both ends of the photoreceptor 2. The main difference is that it has a reciprocating mechanism 32 that reciprocally moves 27 along the rotation direction of the charging roller 1.
[0042]
As shown in FIG. 8, the thickness between the both ends of the charging roller 1 and the photoreceptor 2 is t.₁= 10 μm to t₂A wedge-shaped spacer member 27 that changes to = 50 μm is sandwiched, and the spacer member 27 is fixed by a spacer support member 11 A so that it does not move due to the rotation of the charging roller 1.
[0043]
The reciprocating mechanism 32 is in contact with the rack 12 fixed to the left end of the spacer support member 11A in FIG. 8, the pinion 13 meshing with the rack 12, and the upper and lower surfaces of the non-rack forming portion of the rack 12, and the spacer support member A pair of upper and lower rollers 28 and 28 as guide members for guiding 11A to reciprocate horizontally along the rotation direction of the charging roller 1 and a pinion 13 fixed to the output shaft thereof are fixed to the apparatus main body. It is mainly composed of an electric motor 13B capable of forward and reverse rotation.
The spacer member 27, the spacer support member 11 </ b> A, and the reciprocating mechanism 32 are similarly arranged between both ends of the charging roller 1 and the photoreceptor 2 on the near side and the far side of the paper surface in FIG. 8.
[0044]
The pinion 13 is supported at a fixed position on the apparatus main body side via a bearing (not shown) so as to be rotatable in the clockwise and counterclockwise directions indicated by double arrows in FIG. The reciprocating mechanism 32 allows the spacer member 27 together with the spacer support member 11 </ b> A to be sent out or pulled back in a fixed amount horizontally along the rotation direction of the charging roller 2.
[0045]
For example, the electric motor 13B may be configured to be rotationally driven when the thickness of the spacer member 27 is reduced due to a command from a control device (not shown). A detecting means for detecting indirectly or directly that the thickness of the spacer member 27 has decreased due to wear is appropriately disposed. Based on an output signal from the detecting means, the controller controls the spacer member 27. The electric motor 13B may be controlled so as to adjust the delivery direction and the movement amount.
[0046]
The charging roller 1 is pressed at a constant pressure by a pressing mechanism 29 having a pressing spring 29A (compression spring) or the like that sandwiches the spacer member 27 and urges the charging roller 1 in a direction in which the charging roller 1 is pressed against the photoreceptor 2. ing. Further, the charging roller 1 has core shafts 1c at both ends rotatably supported by bearings 30 (not shown), and rotates in a counterclockwise direction indicated by an arrow in FIG. 8 by a driving mechanism (not shown). .
The photoconductor 2 is supported at both ends of its shaft by a bearing (not shown), and is rotated in a clockwise direction indicated by an arrow in FIG. 8 by a driving mechanism (not shown).
[0047]
  In addition,Reference exampleThe reciprocating mechanism of the present invention is not limited to the reciprocating mechanism 32 as long as it does not require the above-described advantages by electric drive. For example, a handle (not shown) is attached to the pinion 13 and the handle is manually rotated and adjusted. Is also possible.
  The reciprocating mechanism 32 is not limited to the above-described example, and the reciprocating mechanism 32 may be disposed only at one central portion on the near side and the far side of the paper surface in FIG. 8 in order to reduce the number of parts.
[0048]
  Therefore,Reference example shown in FIG.Accordingly, the spacer member 27 whose thickness varies along the rotation direction of the charging roller 1 is reciprocated along the rotation direction of the charging roller 1 by the reciprocating mechanism 32, so that the spacer member 27 has an arbitrary thickness. There is an advantage that the gap G between the charging roller 1 and the photoreceptor 2 can be easily adjusted by moving and fixing to the position.
[0049]
As described above, the present invention has been described with respect to specific embodiments including examples. However, the configuration of the present invention is not limited to the above-described embodiments and modifications, and a combination thereof is appropriately provided. It will be apparent to those skilled in the art that various embodiments and examples can be configured within the scope of the present invention according to the necessity and application thereof.
[0050]
【The invention's effect】
  As described above, according to the present invention, a novel charging device that can solve the above-described problems of the conventional device and achieve the above-described object can be achieved.And image forming apparatusCan be provided. The effects for each claim are as follows.
  According to invention of Claim 1,With the above configuration,With charging rollerCharged body (eg photoconductor)A constant gap can be maintained between the charging roller and the charging roller so that there is no fluctuation in the gap due to one rotation period, and charging unevenness can be eliminated.Along withIt is possible to eliminate gap variation due to construction accuracy as much as possible.In addition, even if the thickness of the contact portion of the spacer member decreases due to wear, the position can be changed to a new contact portion of the spacer member, so that the gap between the charging roller and the member to be charged (for example, the photosensitive member) Can be eliminated. In addition, since the spacer member having a certain thickness moves along the rotation direction of the charging roller by the moving mechanism, the reduction in the thickness of the spacer is restored, so that the charging roller and the member to be charged (for example, the photosensitive member) It is possible to eliminate the reduction of the gap between the two.
[0051]
  According to invention of Claim 2,With the above configuration, it is possible to maintain a constant gap between the charging roller and the member to be charged (for example, a photoconductor), thereby eliminating fluctuations in the gap due to one rotation cycle of the charging roller and eliminating charging unevenness. At the same time, the gap variation due to processing accuracy can be eliminated as much as possible, and even if the thickness of the contact portion of the belt-shaped spacer member having flexibility is reduced due to wear, a new belt-shaped spacer member can be obtained. Since the position can be changed to the contact portion, it is possible to eliminate the decrease in the gap between the charging roller and the member to be charged (for example, the photosensitive member). In addition, since the belt-like spacer member is taken up by the take-up mechanism, the amount of the belt-like spacer member to be fed increases, so that the gap between the charging roller and the member to be charged (for example, the photosensitive member) is kept constant. Time to do.
[0052]
  According to invention of Claim 3,With the above configuration, it is possible to maintain a constant gap between the charging roller and the member to be charged (for example, a photoconductor), thereby eliminating fluctuations in the gap due to one rotation cycle of the charging roller and eliminating charging unevenness. In addition, gap variation due to machining accuracy can be eliminated as much as possible, and even if the thickness of the abutting portion of the rotatable disc-shaped spacer member that forms a disc-like shape decreases due to wear, a new contact of the disc-shaped spacer member Since the position can be changed to the portion, it is possible to eliminate the decrease in the gap between the charging roller and the member to be charged (for example, the photosensitive member). In addition, when the disc-shaped spacer member is rotated by the rotation mechanism, even if the thickness of the disc-shaped spacer member decreases due to wear, the disc-shaped spacer member is rotated and a new disc-shaped spacer member abutting portion is brought out. As a result, the reduction in the thickness of the disk-shaped spacer is restored, so that the reduction in the gap between the charging roller and the member to be charged (for example, the photosensitive member) can be eliminated.
[0053]
  According to invention of Claim 4,By forming the spacer member with a fluororesin material, the friction with the charging roller and the member to be charged (for example, the photoreceptor) is reduced, and the rotational resistance and wear due to the friction can be reduced.
[0054]
  According to invention of Claim 5,The image forming apparatus having the charging device according to any one of claims 1 to 4 exhibits the effect of the invention.
[Brief description of the drawings]
FIG. 1 is a front view around a charging device common to embodiments of the present invention.
FIG. 2 is a simplified partial cross-sectional front view of the charging device according to the first embodiment.
FIG. 3 is a side view of FIG. 2;
FIG. 4 is a simplified partial cross-sectional front view of a charging device according to a second embodiment.
FIG. 5 is a simplified partial cross-sectional front view of a charging device according to a third embodiment.
FIG. 6 is a simplified partial cross-sectional side view of a charging device according to a fourth embodiment.
7 is a plan view of the main part of FIG. 6. FIG.
[Fig. 8]Reference exampleFIG. 2 is a simplified partial cross-sectional front view of the charging device.
[Explanation of symbols]
1 Charging roller
2 Photoconductor as a member to be charged
10, 10A, 16, 27 Spacer member
12 Racks constituting a moving mechanism or a reciprocating mechanism
13 Pinion constituting moving mechanism or reciprocating mechanism
14 Feeding mechanism constituting winding mechanism
15 Winding mechanism constituting the winding mechanism
29 Pressurization mechanism
31 Rotating mechanism
32 Reciprocating mechanism

Claims (5)

In the charging device for charging the charged body by keeping the rotating charging roller in a non-contact state with the charged body at all times,
Sandwiched between the both end portions of the both end portions and the member to be charged the charging roller, and a spacer member of a low frictional resistance with a thickness capable of holding the non-contact state,
Variable means for changing the position of the contact portion of the spacer member that contacts both ends of the charging roller and both ends of the member to be charged;
The spacer member has a certain thickness;
The charging device, wherein the variable means is a moving mechanism that moves the spacer member along a rotation direction of the charging roller . In a charging device for charging a charged body by keeping a rotating charging roller in a non-contact state with the charged body at all times,
A low frictional resistance spacer member sandwiched between both ends of the charging roller and both ends of the charged body and having a thickness capable of maintaining the non-contact state;
Variable means for changing the position of the contact portion of the spacer member that contacts both ends of the charging roller and both ends of the member to be charged;
The spacer member is a belt-like spacer member having a flexible belt-like shape,
The charging device , wherein the variable means is a winding mechanism that winds up the belt-like spacer member . In a charging device for charging a charged body by keeping a rotating charging roller in a non-contact state with the charged body at all times,
A low frictional resistance spacer member sandwiched between both ends of the charging roller and both ends of the charged body and having a thickness capable of maintaining the non-contact state;
; And a changing means for changing the position of the abutting portion of both end portions abutting the spacer member of the opposite end portions and the member to be charged the charging roller,
The spacer member is a rotatable disc-like spacer member having a disc-like shape,
The charging device according to claim 1, wherein the variable means is a rotation mechanism that rotates the disk-shaped spacer member . The charging device according to any one of claims 1 to 3 ,
A charging device , wherein the spacer member is made of a fluororesin material . An image forming apparatus comprising the charging device according to claim 1.

Images