HK1120118A - Image forming device - Google Patents

Description

Image forming apparatus with a toner supply device

Technical Field

The present invention relates to an image forming apparatus having an electrophotographic image forming process section, and more particularly, to an improvement in a cleaning member in a corona discharger constituting the image forming process section.

Background

Image forming apparatuses having an electrophotographic image forming process section are often used in copiers, facsimile machines, printers, so-called multi-functional peripheral machines having these functions, and the like. A corona discharger is incorporated as one component of such an image forming processing unit. Corona dischargers are used for chargers for uniformly charging the surface of a photosensitive drum, transferors for transferring toner images on the surface of a photosensitive drum onto a recording medium (recording paper), and dischargers for removing electricity from the surface of a photosensitive drum. Conventionally, a wire electrode has been used as an electrode of a corona discharger, but there is a problem of generation of ozone, and recently, a needle electrode with less generation of ozone is frequently used.

The corona discharger using the needle electrode is suitable as a charger or the like constituting the image forming process section as described above because ozone is less generated, but foreign matters (toner, paper powder, silicon, or the like) are likely to adhere to the needle electrode with time, and when these deposits increase, discharge unevenness occurs, which may cause an image forming failure. Therefore, a corona discharger having a cleaning device capable of appropriately wiping the surface of the cleaning needle electrode as shown in japanese patent No. 3259515 has been put into practical use. The cleaning device for a corona discharger disclosed in japanese patent No. 3259515 is configured to: the needle electrode is nipped by a pair of rollers rotatably supported, and the pair of rollers is allowed to perform a sliding movement in a longitudinal direction of the needle electrode in such a nipped state.

However, in the cleaning device disclosed in japanese patent No. 3259515, two shaft portions supporting a pair of rollers are biased in directions opposite to each other, and thus the two rollers rotate in a state in which a load acts on both surfaces of the needle electrode. Therefore, the load acts to hinder the rotation of the two rollers, so that the above-described sliding resistance also becomes large. In order to alleviate such a load that hinders the rotation of the rollers, it is necessary to support the rollers on the support shafts by bearing members or support the rotating shafts integral with the rollers by bearing members, and to receive the load by these bearing members.

As a countermeasure against the increase in the number of components, it is conceivable to adopt the following configuration: the needle electrode is cleaned by combining a shaft-rotating sliding member (roller) and a non-rotating sliding member, applying a load only to the non-rotating sliding member, sandwiching the needle electrode between the two members, and sliding the two members. In this case, since the load is not directly applied to the shaft rotation sliding member, a bearing member for alleviating the load for inhibiting the rotation is not required, and a good cleaning function can be realized without increasing the number of components, and it is expected that the practical value will be increased. However, when the two members are slid by sandwiching the two members and sandwiching the needle electrode between the sandwiching portions, the needle portion of the needle electrode may be caught by the sliding surface of the non-rotating sliding member, and the needle electrode may be bent.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide an image forming apparatus having a corona discharger which can realize efficient cleaning without increasing the number of components.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming apparatus including a corona discharger which can perform efficient cleaning without increasing the number of components and which does not cause a scratch of a needle electrode in accordance with a cleaning operation.

An image forming apparatus of the present invention is an image forming apparatus having a corona discharger, characterized in that: the corona discharger comprises a needle electrode and a cleaning member which holds the needle electrode and is slidable in a longitudinal direction thereof, wherein the cleaning member comprises: a moving body mounted on a housing portion of the corona discharger so as to be capable of reciprocating along a longitudinal direction of the needle electrode; two sliding members supported by the moving body and sandwiching the needle electrode from both sides; and a biasing member provided between the movable body and the sliding contact member so that the sliding contact member on one side applies an elastic force to the sliding contact member on the other side.

In the present invention, the one sliding contact member may be a non-rotating member that is non-rotatably supported by the movable body so as to be movable toward the other sliding contact member, and the other sliding contact member may be a shaft rotating member that is rotatably supported around a shaft by a bearing portion of the movable body. The corona discharger may be used as a charger for charging the surface of the photosensitive drum constituting the image forming process unit.

An image forming apparatus of the present invention is an image forming apparatus having a corona discharger, characterized in that: the corona discharger includes a housing, a needle electrode stretched in the housing, and a cleaning member which holds the needle electrode and is slidable in a longitudinal direction thereof, the cleaning member including: a moving body mounted on the housing portion so as to be capable of reciprocating in a longitudinal direction of the needle electrode; two sliding members each composed of a combination of a non-rotational sliding member and a shaft-rotational sliding member supported by the movable body and holding the needle electrode from both sides; and a biasing member provided between the movable body and the non-rotating sliding member so that the non-rotating sliding member applies an elastic force to the shaft-rotating sliding member. The mutual positions of the two sliding members are set as follows: the clamping part is slightly deviated to the non-rotating sliding part side than the stretching line of the needle electrode.

In the present invention, the non-rotating sliding contact member may be supported by the movable body so as to be movable toward the shaft rotating sliding contact member and non-rotatable, and the shaft rotating member may be supported by a bearing portion of the movable body so as to be rotatable about the shaft. The corona discharger may be used as a charger for charging the surface of the photosensitive drum constituting the image forming process unit.

In the image forming apparatus of the present invention, the corona discharger includes the needle electrode and the cleaning member which holds the needle electrode and is slidable in the longitudinal direction thereof, and therefore, the needle electrode can be cleaned by sliding the cleaning member in the longitudinal direction of the needle electrode. The cleaning member includes: a moving body mounted on a housing portion of the corona discharger so as to be capable of reciprocating in a longitudinal direction of the needle electrode; two sliding members supported by the moving body and sandwiching the needle electrodes from both sides; and a biasing member provided between the movable body and the sliding contact member so that the sliding contact member on one side applies an elastic force to the sliding contact member on the other side, so that when the needle electrode is held between the two sliding contact members and the movable body is reciprocated, the needle electrode can be reciprocated while the sliding contact member on one side applies an elastic force to the sliding contact member on the other side by the biasing member, and thus both surfaces of the needle electrode are elastically held, and wiping and cleaning of toner, silicon, and the like can be effectively performed. Further, since a load is applied to only one of the two sliding members, the sliding resistance does not increase, and it is not necessary to provide bearing members for receiving the load to relax the load on the two sliding members, and the number of members does not increase.

In the case where the one sliding contact member is constituted by the non-rotating sliding contact member which is supported by the movable body so as to be movable to the other sliding contact member side and non-rotatable, and the other sliding contact member is constituted by the shaft rotating member which is supported by the bearing portion of the movable body so as to be rotatable about the shaft, since the load is not directly applied to the shaft rotating member but applied to the non-rotating member, it is not necessary to provide the bearing portion which supports the shaft rotating member so as to be rotatable about the shaft, and another member provided so as not to inhibit the rotation of the shaft rotating member, and the number of members is effectively reduced.

In the image forming apparatus of the present invention, the corona discharger includes the needle electrode and the cleaning member which holds the needle electrode and is slidable in the longitudinal direction thereof, and therefore, the needle electrode can be cleaned by sliding the cleaning member in the longitudinal direction of the needle electrode. The cleaning member includes: a moving body mounted on a housing portion of the corona discharger so as to be capable of reciprocating in a longitudinal direction of the needle electrode; two sliding members each composed of a combination of a non-rotational sliding member and a shaft-rotational sliding member supported by the movable body and holding the needle electrode from both sides; and a biasing member provided between the movable body and the non-rotational sliding contact member so that the non-rotational sliding contact member applies an elastic force to the rotational sliding contact member; therefore, when the needle electrode is held between the two sliding members and the moving body is reciprocated, the needle electrode can be reciprocated while the non-rotating sliding member is caused by the urging member to apply an elastic force to the rotating sliding member, whereby both surfaces of the needle electrode are elastically held, and wiping and cleaning of toner, silicon, and the like can be effectively performed. Further, since the load is applied only to the non-rotating sliding contact member, the sliding resistance does not increase, and it is not necessary to provide bearing members for receiving the load for load alleviation in the two sliding contact members, and the number of components does not increase.

In addition, the mutual positions of the non-rotating sliding member and the shaft rotating sliding member are set as follows: since the clamping portion is located slightly closer to the non-rotating slidable member side than the tension line of the needle electrode, the needle portion of the needle electrode is less likely to be introduced into the clamping portion from the non-rotating slidable member side during the reciprocating movement of the movable body, and therefore the needle electrode is less likely to be bent due to the needle portion being scraped against the non-rotating slidable member side. Further, although the needle electrode is highly likely to be introduced into the nip portion from the shaft rotation sliding member side, the shaft rotation sliding member rotates around the shaft in accordance with the relative movement of the needle electrode, and therefore, the scraping resistance of the needle portion is reduced, and the needle electrode is less likely to be bent.

When the non-rotatable sliding member is supported by the movable body so as to be movable toward the shaft-rotatable sliding member and non-rotatable, and the shaft-rotatable sliding member is supported by the bearing portion of the movable body so as to be rotatable about the shaft, a load is applied to the non-rotatable sliding member and an acting load is not directly applied to the shaft-rotatable sliding member.

Further, when the corona discharger is used as a charger for charging the surface of the photosensitive drum constituting the image forming process unit, the applicability as a cleaning device for a charger which is easy to adhere toner, paper dust, silicon, and the like to the needle electrode is further increased.

Other features, elements, processes, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.

Drawings

Fig. 1 is a schematic longitudinal sectional view showing an image forming apparatus according to an embodiment of the present invention.

Fig. 2 is a longitudinal sectional view of a drum unit in the image forming apparatus of fig. 1.

Fig. 3 is a perspective view of a charger incorporated in the image forming apparatus of fig. 1.

Fig. 4 is a partially sectional perspective view seen from the X-ray direction indicated by an arrow in fig. 3.

Fig. 5 is an exploded perspective view of the cleaning member attached to the charging unit of fig. 3.

Fig. 6 is a sectional view taken along line Y-Y in fig. 4.

Fig. 7 is a cross-sectional view taken along line Z-Z in fig. 6.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a schematic longitudinal sectional view showing an image forming apparatus according to an embodiment of the present invention, fig. 2 is a longitudinal sectional view of a drum unit in the image forming apparatus, fig. 3 is a perspective view of a charging unit incorporated in the image forming apparatus, fig. 4 is a partially sectional perspective view seen from an X-line direction indicated by an arrow in fig. 3, fig. 5 is an exploded perspective view of a cleaning member attached to the charging unit, fig. 6 is a sectional view taken along a Y-Y line in fig. 4, and fig. 7 is a sectional view taken along a Z-Z line in fig. 6.

The image forming apparatus a shown in fig. 1 is exemplified by a printer having an electrophotographic recording unit, but is not limited to this, and may be a copying machine having an image reading device, a facsimile machine, a so-called multifunction peripheral having both of these functions, or the like. In the figure, an apparatus main body 1 of an image forming apparatus a is configured by stacking a paper feeding section 2 for recording paper (paper), an image recording section 3 of an electrophotographic system, and a discharge section 4 for printed recording paper in this order in the height direction. The recording paper feeding section 2 includes: a push-pull type paper feed cassette 2a capable of stacking and storing a plurality of recording sheets, a separation paper feed roller 2b provided at a front end portion of the paper feed cassette 2a in a paper feed direction, and a separation pad 2c elastically contacting a periphery of the separation paper feed roller 2 b.

Further, the following may be configured: the same cassettes are further stacked below the paper feed cassette 2a to form a multi-stage cassette, or an optional cassette (not shown) may be provided. Further, a retard roller may be provided instead of the above-described separation pad 2 c.

The image recording section 3 includes a processing section in which a corona charging type charger (corona discharger) 6, an exposure unit 7 including an LED or the like, a developing unit 8, a transfer roller (transfer unit) 9, and a cleaning device 10 for removing toner remaining at the time of transfer are arranged in this order around the photosensitive drum 5, and a fixing unit 11 on the downstream side thereof. The processing section is formed as a processing unit constituted by a drum unit 50 and a developer unit 80, in addition to the exposer 7 and the transfer roller 9, wherein the drum unit 50 includes the photosensitive drum 5, the charger 6, and the cleaning device 10; the developer unit 80 includes a developer housing 81, agitating conveyance screws 82, 83, a supply paddle 84, a developing roller 85, and the like.

The illustrated developer unit 80 is a developer of a type using a two-component developer, and is configured to: the toner and the carrier are accommodated in a developer housing 81, and the developer housing 81 also serves as a developer container formed by resin molding, and the developer is supplied to a developing roller 85 to which a bias is applied by a supply paddle 84 while being stirred and conveyed by two parallel stirring and conveying screws 82, 83. A magnetic sensor 86 is attached to an outer surface of the developing device case 81 to detect a toner concentration (a mixing ratio of toner and carrier) in the developing device case 81. A toner container 12 and a toner hopper 13 as toner containing portions are provided at a position away from the developing unit 80, and when the magnetic sensor 86 detects that the toner concentration in the developing housing 81 has decreased, the toner is replenished from the toner hopper 13 into the developing housing 81 by a screw conveyor (pipe screw) 14. The toner container 12 is provided with a toner stirring agitator 15 and a toner conveying and discharging screw 16 for conveying and discharging toner to and from the toner hopper 13, and the toner container 12 provided with the toner stirring agitator 15 and the toner conveying and discharging screw 16 is formed integrally with a waste toner container 17 described later and is configured as a toner cartridge 18 detachably attached to the apparatus main body 1.

The drum unit 50 and the developer unit 80 are detachably mounted to the apparatus main body 1 from the front side of the apparatus main body 1 in a state where they are coupled to each other individually or by some coupling means. Further, it may be a process unit in which all the process sections other than the exposure device 7 and the transfer roller 9 are integrated. The toner cartridge 18 is also detachably attached to the apparatus body 1 from the front side of the apparatus body 1. These process units 50, 80 and the developer cartridge 18 are consumable items, and can be replaced with appropriate new items. Here, the front side of the apparatus main body 1 refers to a side close to a person on the paper surface of fig. 1. The paper feed cassette 2a may be pushed or pulled with respect to the apparatus main body 1 from the front side of the apparatus main body 1.

To the waste toner container 17 constituting the toner cartridge 18, an auger 19 is connected, and the auger 19 is used to gradually convey and throw the waste toner removed and recovered by the cleaning device 10 into the waste toner container 17. The waste toner discharged from the waste toner discharge port and charged into the waste toner container 17 is dispersed and accumulated in the waste toner container 17 by a conveyance screw 17a disposed in the waste toner container 17.

A switching gate 4a, a discharge roller pair 4b, and a discharge tray 4c, which constitute the discharge portion 4, are provided in series on the downstream side of the fixing device 11. A registration roller pair 20 is disposed in the vicinity of the upstream side of the processing unit, and recording paper (paper) is separated one by one from the paper feed cassette 2a by a separation paper feed roller 2b and a separation pad 2c, fed out, and then registered by the registration roller pair 20 and introduced into a registration portion between the photosensitive drum 5 and the transfer roller 9. The surface of the photosensitive drum 5 is uniformly negatively charged by the charger 6 while the photosensitive drum 5 rotates in the direction of the arrow in fig. 1, and an optical image based on image information is irradiated onto the surface of the photosensitive drum 5 by the exposure unit 7 to form an electrostatic latent image on the surface of the photosensitive drum 5. The electrostatic latent image is formed such that the potential of the light irradiated portion changes according to the characteristics of the photoconductor on the surface of the photosensitive drum 5, while the potential of the other portions remains unchanged.

Then, the electrostatic latent image is developed step by the developing device 8 to which a bias is applied, and is sent to a joint portion of the photosensitive drum 5 and the transfer roller 9 as a toner image. In this development, a potential difference between the developing unit 8 and a portion where the potential is changed by light irradiation causes the toner to be attracted to the photosensitive drum 5 and changed to a black portion, and the other portion is changed to a white portion without attracting the toner, so that a black-and-white toner image is formed based on image information as a whole. After the registration control, the registration roller pair 20 is rotationally driven so that the recording paper and the toner image on the surface of the photosensitive drum 5 are synchronously guided to the mating portion.

The transfer roller 9 is biased and is rotationally driven in the direction of the arrow (the direction in which the transfer roller rotates with the photosensitive drum 5) together with the photosensitive drum 5, and is conveyed with the recording paper therebetween, and at this time, the toner image on the surface of the photosensitive drum 5 is transferred onto the recording paper. The toner and the like (including paper dust in some cases) remaining on the surface of the photosensitive drum 5 are removed and collected by the cleaning device 10. The recording paper with the toner image transferred thereto is guided to the fixing device 11, fixed as a permanent image, and then ejected to the ejection tray 4c via the pair of ejection rollers 4b by pushing up the switching gate 4 a. The feeding of the series of recording sheets is performed along a main feeding path P which is raised substantially vertically immediately after being drawn out from the sheet feeding cassette 2a, and is U-folded at the pair of sheet discharging rollers 4b to be turned substantially 180 degrees from the direction drawn out from the sheet feeding cassette 2 a. With such a layout structure, the entire device can be miniaturized.

The illustrated image forming apparatus a has a double-sided recording function, and a reverse feeding/discharging path P1 merging into the main feeding/discharging path P in a circulating manner is formed from the mounting position of the switching gate 4a of the main feeding/discharging path P to the upstream side of the registration roller pair 20. The discharge roller pair 4b is rotatable in the forward and reverse directions. Further, the reverse feeding and discharging path P1 is provided with the pair of transport rollers 21 and 22, and when double-sided recording is performed, the recording paper subjected to single-sided recording as described above is transported along the main feeding and discharging path P, and when the trailing edge of the recording paper reaches the pair of discharge rollers 4b, the pair of discharge rollers 4b is temporarily stopped, and sandwiches the trailing edge of the recording paper. Then, the discharge roller pair 4b is reversed, and the recording paper is conveyed on the reverse feeding and discharging path P1 from the trailing end thereof by the conveying roller pairs 21 and 22, and merges into the main feeding and discharging path P and reaches the registration roller pair 20. The recording paper is positioned by the registration roller pair 20, and is again guided to the mating portion between the photosensitive drum 5 and the transfer roller 9, and recording is performed on the reverse side thereof. The recording paper subjected to the double-sided recording is then discharged onto the discharge tray 4c along the main feeding and discharging path P as described above.

The illustrated image forming apparatus a further has a function of manually feeding recording paper, and a three-stage manual paper feed tray 23 that can be opened and closed vertically and is slidable and extendable is attached to a side portion of the apparatus main body 1. The manual feed tray 23 is closed in a contracted state as shown by a two-dot chain line in fig. 1 when not in use, and is opened by pulling the handle 23a when in use, and is appropriately pulled in accordance with the size of a recording sheet placed for feeding the sheet. A manual separation paper feed roller 23b and a separation pad 23c are provided in elastic contact with the front end of the manual paper feed tray 23, and a manual paper feed path P2 merging into the main paper feed path P is provided continuously on the downstream side thereof.

The toner hopper 13 is used to temporarily store the toner supplied from the toner container 12, and when the magnetic sensor 86 of the developing device 8 sends a signal that there is no toner, the screw conveyor 14 connected to the toner hopper 13 operates, and the toner is supplied into the developing device casing 81. In order to always store a predetermined amount of toner in the toner hopper 13, the operation of the toner conveying and discharging screw 16 is controlled based on a detection signal of a sensor (not shown) provided in the toner hopper 13. The predetermined amount of toner stored in the toner hopper 13 is set to, for example: the toner in the toner container 12 is depleted, and the printing operation can be continued for a sufficient amount until the toner cartridge 18 is replaced with a new one.

Next, referring to fig. 2, the photosensitive drum unit 50 integrally provided with the charger 6 will be described in detail. The photosensitive drum 5 is formed by coating a photoconductor on the surface of a conductive cylindrical body made of aluminum or the like, and flange members 5a and 5b made of insulating resin or the like are fixed to openings at both ends thereof. The photosensitive drum 5 has a shaft (drum shaft) 51c coaxially inserted through flange members 5a and 5b at both ends thereof, and is supported by a unit frame 51 made of a resin molded product through bearings 51a and 51b so as to be rotatable about the axis. Gears 5c and 5d are concentrically formed on the peripheral surfaces of the flange members 5a and 5b, and the gear 5c is engaged with a drive transmission system, not shown, in the apparatus main body 1 to obtain a driving force thereof, so that the photosensitive drum 5 is axially rotated about the drum shaft 51 c. A driven transmission gear (not shown) of a mechanism portion such as the transfer roller 9 meshes with the gear 5d on the opposite side, and transmits rotational drive to these mechanism portions.

The charger 6 is composed of a Scorotron type corona discharger, and is formed by unitizing: a pair of mounting members 61, 62 fixed to both end portions of the unit frame 51, a needle electrode 63 stretched between the mounting members 61, 62, a shield case (case portion) 64 having a U-shaped cross section which is coupled to the mounting members 61, 62, supported between them and covers the needle electrode 63, and a grill 65 stretched between the mounting members 61, 62 and disposed in an opening portion on the photosensitive drum side of the shield case 64. The mounting members 61, 62 are connected and fixed to the unit frame 51 by screws 61b, 62b through screw holes 61a, 62a formed respectively.

The needle electrode 63 is an electrode for corona discharge, and is formed of a thin strip metal plate-like body having a plurality of needle electrodes 63a. One end 63b of the needle electrode 63 is hung in the one mounting member 61, and the other end 63c is hung in the other mounting member 62 by a tension spring 63d, and is stretched between the two mounting members 61, 62 in a state where tension is applied. The grill 65 is formed of a thin metal plate having a plurality of slits formed therein, and one end 65a thereof is hung on the one mounting member 61, and the other end 65b thereof is hung on the other mounting member 62 via a swinging member 65c and a tension spring 65 d.

The swinging member 65c is disposed so as to penetrate from the photosensitive drum 5 side to the opposite side thereof, and is swingably supported by the mounting member 62 with the fulcrum pin 65ca as a fulcrum. The other end 65b of the grill 65 is hung on the side of the swinging member 65c projecting from the photosensitive drum 5, and the extension spring 65d is hung on the opposite side of the swinging member. When the photosensitive drum unit 50 is mounted at a predetermined position in the image forming apparatus a, the pin electrode 63 and the grid 65 are connected to a power supply electrode (not shown) in the apparatus main body 1, and predetermined voltages are applied thereto. Further, the two mounting members 61, 62 and the shield shell 64 have been integrated.

The charging unit 6 includes a cleaning member 24 that holds the needle electrode 63 and is slidable in the longitudinal direction thereof. As shown in fig. 2 to 7, the cleaning member 24 includes: a moving body 25 mounted on the shield case 64 so as to be capable of reciprocating in the longitudinal direction of the needle electrode 63; two sliding members 30 and 31 supported by the moving body 25 and sandwiching the needle electrode 63 from both sides; and a biasing member 32 provided between the movable body 25 and the sliding contact member 30 so that one sliding contact member 30 applies an elastic force to the other sliding contact member 31. The moving body 25 is formed of an コ -shaped moving body 26 holding the two sliding members 30 and 31, a pressing member 27 for pressing the sliding members 30 and 31 so as not to be detachable is supported by the moving body 26, and a mounting member 28 for mounting the moving body 25 to the tip of the operating lever 29 is fixed to the back of the moving body 26 by a screw 28 a. When the movable body 26 and the mounting member 28 are integrally fixed by the screw 28a, the screw penetrates an opening 64a provided in the back of the U-shaped shield case 64 along the longitudinal direction thereof, and sandwiches the opening peripheral edge portion across the width direction thereof. In a state where the moving body main body 26 and the mounting member 28 are integrated, the moving body main body can move in the longitudinal direction of the shield case 64 (the needle electrode 63) in the opening 64 a.

The movable body 26 has two legs formed to be elastically deformable, and has locking claws 26a and 26b formed at the distal ends thereof. The locking claws 26a and 26b are inserted into the pressing member 27 through locking holes 27a and 27b formed in the pressing member 27 and locked by the pressing member 27, whereby the pressing member 27 is attached to the moving body 26 so as to hold the two slidable members 30 and 31 at predetermined positions so as not to be disengaged therefrom as will be described later.

The one sliding contact member 30 is constituted by a non-rotating sliding contact member which is supported by the moving body main body 26 so as to be movable toward the other sliding contact member 31 and non-rotatable. More specifically, the non-rotating sliding-contact member 30 includes a sliding-contact portion 30a having a semicircular cross section, a base portion 30b having a concave cross section and formed integrally with the sliding-contact portion 30a along the longitudinal direction on the back side thereof, and locking pins 30c and 30d formed at both ends in the longitudinal direction. In the state where the non-rotating slidable member 30 is attached to and held by the movable body 25, the locking pins 30c and 30d at both ends thereof are inserted into the elongated holes 26c and 27c formed in the movable body 26 and the pressing member 27. The long holes 26c, 27c are oriented in the longitudinal direction in the direction of opposition of the two sliding members 30, 31, so that the non-rotating sliding member 30 can move in the direction of opposition (see the direction indicated by the arrow a in fig. 6) in the attached and held state.

The base portion 30b engages the base portion of the locking hole 27a and the elastic member 26d in a manner surrounding them in the recess thereof, and the oblong locking pin 30d is in an engagement relationship with the oblong hole 26c, and the non-rotatable slide-on member 30 is not rotatable about the axis in the attached and held state, wherein the elastic member 26d is formed in a cantilever manner on the leg portion side on one side of the movable body main body 26. A projection 30e is formed on the inner surface of the recess of the base 30b, and the projection 30e abuts on the elastic member 26d in the attached and held state, and elastically deforms the elastic member 26d from the two-dot chain line to the solid line position in fig. 6 and 7. The elastic member 26d functions to apply an elastic force to the non-rotating sliding contact member 30 toward the other shaft rotating sliding contact member 31 side due to its restoring elastic force, thereby constituting the urging member 32.

The shaft rotation sliding member 31 is composed of a roller member 31a having a circular cross section and rotation support shafts 31b and 31c coaxially formed at both ends in the longitudinal direction thereof. In the movable body 26 and the pressing member 27, a shaft hole 26e and a shaft hole 27d are formed as bearing portions, and in the above-described attached and held state where the shaft rotation sliding member 31 is attached and held to the movable body 25, the rotation support shafts 31b and 31c are supported by the shaft hole 26e and the shaft hole 27d, and the shaft rotation sliding member 31 is rotatable around the axial centers of the rotation support shafts 31b and 31 c. The two sliding members 30 and 31 are attached to the moving body 26 and the pressing member 27 so as to sandwich the needle electrode 63 of the charger 6 from both sides, are held by the moving body 26 and the pressing member 27, and are attached to the shield case 64 by the attachment member 28 coupled to the tip end of the operating lever 29, thereby constituting the cleaning member 24 slidable in the longitudinal direction of the needle electrode 63. The two sliding members 30 and 31 and the moving body 25 are preferably formed of an integral resin molding.

The mutual positions of the two sliding members (non-rotating sliding member and shaft-rotating sliding member) 30 and 31 are set as follows: the nip portion n is positioned slightly closer to the non-rotatable sliding contact member 30 than the extension line L of the needle electrode 63, as shown in fig. 6. Therefore, when the movable body 25 is reciprocated as described later and the needle electrode 63 is cleaned by the cleaning member 24, the sliding members 30 and 31 are slid in a state where the needle electrode 63 is gently bent at the nip portion n. The offset width δ of the nip portion n from the tension line L toward the non-rotatable slider 30 side is set to: the sliding resistance of the sliding members 30, 31 is not excessive.

The following describes the cleaning procedure of the needle electrode 63 in the charging unit 6 having the cleaning member 24 configured as described above. As shown in fig. 2 and 3, an operation grip 29a is formed on the base side of the operation lever 29 (on the side of an unillustrated opening/closing door provided in the apparatus body 1), and an operator opens the opening/closing door and repeatedly pushes and pulls the operation grip 29 a. By this pushing and pulling operation, the cleaning member 24 repeatedly reciprocates along the longitudinal direction of the needle electrode 63 as shown by arrow b in fig. 6. During this reciprocating movement, the needle electrode 63 is held between the two sliding members 30 and 31, and therefore, the sliding action of the sliding members 30 and 31 can wipe off the adhering toner, paper powder, silicon, and the like. Then, the biasing member 32 applies a biasing force in the direction of arrow a to the non-rotating sliding contact member 30. This elastically sandwiches the needle electrode 63 between the two sliding members 30 and 31, and therefore, wiping can be effectively performed.

When the needle electrode 63 reciprocates in a state of being urged in this manner, the sliding member 31 is rotated about the shaft, and the needle electrode rotates about the shaft as indicated by arrow c in fig. 6 in accordance with the relative movement of the needle electrode 63. This allows the cleaning member 24 to smoothly reciprocate. Since the shaft rotation sliding member 31 does not directly receive the load by the elastic force, the load does not hinder the sliding thereof. The non-rotating sliding contact member 30 has a semicircular sliding contact portion 30a that elastically slides on the needle electrode 63 in a state where the sliding contact member 31 is always elastically urged against the shaft. Since the curved surface portion of the sliding contact portion 30a is a sliding surface with the pin electrode 63, the resistance to the elastic sliding is small. Such a function of the cleaning member 24 can be realized without using a bearing member for receiving a load, and is effective for reducing the number of components.

Since the nip portion n of the sliding contact members 30 and 31 is offset toward the non-rotating sliding contact member 30 by the width δ from the tension line L of the needle electrode 63, the needle electrode 63a of the needle electrode 63 is introduced into the nip portion n from the side of the shaft-rotating sliding contact member 31 (see fig. 2) when the sliding contact members 30 and 31 slide. Therefore, the degree of contact between the needle-like electrodes 63a and the sliding contact portion 30a of the non-rotating sliding contact member 30 is reduced, and the possibility of the needle-like electrodes 63a being scraped by the surface of the sliding contact portion 30a is low. Thereby, the possibility of bending of the needle electrode 63 caused by the scratch is also reduced. Although the needle electrode 63 is highly likely to be introduced into the nip portion n from the shaft-rotation sliding member 31 side, the shaft-rotation member 31 rotates around the shaft in response to the relative movement of the needle electrode 63, and therefore, the scraping resistance of the needle electrode 63a.

In addition, although the example in which the corona discharger is the charger has been described in the above embodiment, the present invention can be applied to another corona discharger provided around the transfer device and the photosensitive drum as needed. In addition, as the biasing member 32, a member including a plate spring and another elastic biasing member may be used in addition to the elastic member 26d and the projection 30e shown in the figure. In addition, although the example in which the process units 50, 80 and the toner cartridge 18 are attached from the front side of the apparatus main body 1 has been described, the present invention can be applied to the case where they are attached from the left and right side surfaces or the back surface side, as well as from above. Further, although the embodiment using a two-component developer is described as an example of the developing device 8, the present invention is not limited to this, and is also applicable to a one-component developing method.

While the invention has been described with reference to preferred embodiments, it will be apparent to those skilled in the art that the invention may be modified in numerous ways and may assume many embodiments other than those specifically set out and described above. Accordingly, it is intended by the appended claims to cover all modifications of the invention which fall within the true spirit and scope of the invention.

Claims (6)

1. An image forming apparatus having a corona discharger,

the corona discharger comprises a needle electrode, and a cleaning component which clamps the needle electrode and can slide along the length direction of the needle electrode;

the cleaning member includes: a moving body mounted on a housing portion of the corona discharger so as to be capable of reciprocating in a longitudinal direction of the needle electrode; two sliding members supported by the moving body and sandwiching the needle electrodes from both sides; and a biasing member provided between the movable body and the sliding contact member so that the sliding contact member on one side applies an elastic force to the sliding contact member on the other side.

2. The image forming apparatus according to claim 1,

the sliding contact member on the one side is constituted by a non-rotating member which is supported by the movable body so as to be movable to the sliding contact member on the other side and non-rotatable;

the other sliding member is constituted by a shaft rotating member which is pivotally supported by a bearing portion of the movable body.

3. The image forming apparatus according to claim 1 or 2,

the corona discharger is a charger for charging the surface of the photosensitive drum.

4. An image forming apparatus having a corona discharger,

the corona discharger comprises a casing, a needle electrode stretched in the casing, and a cleaning member which holds the needle electrode and is slidable in the longitudinal direction of the needle electrode;

the cleaning member includes: a moving body mounted on the housing portion so as to be capable of reciprocating in a longitudinal direction of the needle electrode; two sliding members each composed of a combination of a non-rotational sliding member and a shaft-rotational sliding member supported by the movable body and holding the needle electrode from both sides; and a biasing member provided between the movable body and the non-rotational sliding contact member so that the non-rotational sliding contact member applies an elastic force to the rotational sliding contact member;

the mutual positions of the two sliding members are set as follows: the clamping part is slightly deviated to the non-rotating sliding part side than the stretching line of the needle electrode.

5. The image forming apparatus according to claim 4,

the non-rotatable sliding member is supported by the movable body so as to be movable but not rotatable toward the shaft-rotatable sliding member, and the shaft-rotatable sliding member is supported by a bearing portion of the movable body so as to be rotatable about an axis.

6. The image forming apparatus according to claim 4 or 5,

the corona discharger is a charger for charging the surface of the photosensitive drum.