JP2006030284A - Developing device and image forming apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple structure developing device for securely stirring and mixing toner and developer and supplying the mixture to a developing roller. <P>SOLUTION: The developing device 1 has a housing 11 divided into two compartments by a partition plate 16 such that the two compartments communicate with each other only at both their ends. The side of one of the compartments of the housing 11 is open and the developing roller 13 is disposed in the opening. A toner supply port 50 is formed in the upper wall of the other compartment of the housing 11. Spiral stir rollers 12a and 12b are disposed in the corresponding compartments of the housing 11. In addition, a rib 15 is formed around the toner supply port 50 so as to extend a position below the average liquid surface of developer supplied into the housing 11 and cover the toner supply port 50. Further, shielding plates 17a and 17b are arranged at regular intervals in the width direction a prescribed distance away from the toner supply port 50. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing device that performs development by supplying toner to an electrostatic latent image formed on an image carrier, and an image that includes the developing device and that forms an image on a recording medium from toner supplied to the image carrier. The present invention relates to a forming apparatus.

  In an image forming apparatus using an electrophotographic recording method or an electrostatic recording method, an electrostatic latent image is formed on the surface of a photosensitive drum as an image carrier, and toner is attached to the electrostatic latent image from a developing device. To visualize. Then, the toner image thus formed is transferred and fixed to a recording sheet or the like as a recording medium, thereby forming a desired image.

  As developing devices for supplying toner to an electrostatic latent image, there are a two-component developing method of a magnetic brush developing method using toner and a developer (carrier) and a one-component developing method using only a toner. Even if this method is used, if the toner in the developing device is reduced by supplying toner to the image carrier, new toner must be replenished from a toner supply unit such as a toner cartridge.

FIG. 6 is a side sectional view showing a configuration of a conventional developing device and a toner cut ridge.
As shown in FIG. 6, the conventional developing device includes agitation rollers 12 a and 12 b arranged in parallel in the housing 11, and arranged in one opening of the housing 11 and arranged in parallel with the agitation rollers 12 a and 12 b. And a developing roller 13 in contact with the photosensitive drum, and a doctor blade 14 in contact with the developing roller 13. Further, a replenishing port 50 to which the toner cartridge 2 is connected is formed on the upper surface of the end portion side facing the developing roller 13 side of the housing 11. The replenishing port 22 is connected to the replenishing roller 22 side, and the toner cartridge 2 including the stirring blades 21 is connected to the inside. In such a configuration, the toner supplied from the toner cut ridge 2 is agitated by the agitating rollers 12 a and 12 b together with the developer in the housing 11 of the developing device and is supplied to the developing roller 13.

  However, in the developing device having such a configuration, the toner is dropped from above the developer and stirred by the stirring rollers 12a and 12b disposed in the developer, so that the toner dropped on the developer interface is sufficient. Are not agitated, or directly adhere to the photosensitive drum 3 through the space in the housing 11 or are separated into the image forming apparatus.

  Furthermore, in recent years, the toner has become smaller in size due to higher image quality, and it is not easy to mix (stir) the toner with the developer, and the toner is more easily released.

In order to solve such a problem, Patent Document 1 discloses a developing device having a structure as shown in FIG.
FIG. 7 is a side sectional view showing a schematic configuration of the developing device described in Patent Document 1.
As shown in FIG. 7, the developing device includes a stirrer in which a casing 51 is provided with a stirrer roller 52 and a developing roller 53, and the toner supplied from the toner cartridge 2. And a buffer unit 60 including stirring rollers 61 and 62 for preliminary stirring once. The buffer unit 60 includes a first tank provided with a stirring roller 61 and a second tank provided with a stirring roller 62 by a baffle plate 63. In the developing device having such a configuration, first, the toner is stirred together with the developer supplied from the stirring unit via the connection port 55 in the first layer of the buffer unit 60, and then stirred in the second layer of the buffer unit 60. Is done. Then, the toner and developer stirred in the buffer unit 60 are supplied to the stirring unit including the stirring roller 52 through the first connection port 55. In the stirring unit, the supplied mixed liquid of toner and developer is further stirred and supplied to the developing roller 13.
JP 11-258894 A

  However, in the configuration described in Patent Document 1, since the inside of the developing device is composed of two upper and lower layers, and stirring is performed using the stirring roller in each of the upper and lower two layers, the structure of the developing device becomes complicated, The device becomes large.

  Accordingly, an object of the present invention is to suppress the contamination of the photosensitive drum and the image forming apparatus due to the supply of the re-separated toner due to insufficient stirring to the photosensitive drum and the scattering of the toner even for a small-diameter toner. Another object of the present invention is to provide a developing device and an image forming apparatus including the developing device.

  According to the present invention, in a developing device that agitates a toner and a developer supplied from a toner supply port into a housing with a stirring roller and supplies the developer to the surface of the developing roller, a predetermined opening that opens only the direction of the stirring roller near the toner supply port The housing is provided with a first shielding member that forms a space and restricts the flow of toner and developer in the direction of the developing roller.

  In this configuration, the toner supplied from the toner supply port has a predetermined volume that opens only to the stirring roller surrounded by the upper wall of the housing near the toner supply port of the developing device housing and the first blocking member. Supplied only in space. At this time, the presence of the first blocking member prevents the toner from scattering from the closed space to the outside. Then, only in this space, the toner comes into contact with the developer separately supplied into the housing, and is stirred by the stirring roller so that they are mixed.

  Further, the developing device of the present invention is characterized in that the first shielding member is formed in a shape extending from the inner wall on the upper surface side of the housing to at least the lower side than the average liquid surface.

  In this configuration, the first blocking member is formed so as to extend below the liquid level of the mixed liquid composed of toner and developer, so that the open surface side of the space is blocked by the liquid level and the toner is supplied. The space thus formed becomes a substantially closed space, and the toner is prevented from scattering from the closed space to the outside. That is, toner scattering is reliably prevented. Further, at this time, since the shearing force acts on the mixed solution of the toner and the developer from the first shielding member, the stirring ability is further improved.

  Further, the developing device of the present invention is characterized in that the first shielding member is formed in a shape extending from the average liquid level to the lower side by 3 mm or more.

  In this configuration, since the lower end of the first shielding member is 3 mm or more below the liquid level of the mixed solution, it does not depend on the supply state of the developer or the supply state of the mixed solution of toner and developer to the developing roller. Thus, the closed space is more reliably formed. For this reason, toner scattering can be prevented more reliably.

  The housing of the developing device according to the present invention includes a plurality of spiral stirring rollers each between the toner supply port and the developing roller, and is parallel to the axial direction of the stirring roller between the plurality of stirring rollers. The second shielding member extending in the direction is provided.

  In this configuration, since the stirring roller has a spiral shape, the mixed liquid moves in the axial direction according to the rotation of the stirring roller. And since the mixed liquid moves in the axial direction of the agitation roller by arranging a plurality of agitation rollers, the agitation time of the toner and the developer becomes longer due to this movement, and the agitation is more reliably agitated. Insufficient liquid mixture is prevented from moving to the developing roller. Furthermore, by disposing the second shielding member between the stirring rollers, the liquid mixture moving in the direction perpendicular to the axial direction is suppressed from moving, and the insufficiently stirred liquid mixture is supplied to the developing roller. Is further suppressed.

  Further, the housing of the developing device according to the present invention includes a plurality of third blocking members that restrict the flow of the toner and the developer between the toner supply port and the downstream end of the toner and the developer of the second blocking member. It is characterized by providing.

  In this configuration, when the mixed solution moves in the axial direction of the stirring roller, a shearing force acts on the mixed solution by the third blocking member, and the stirring ability is improved.

  An image forming apparatus according to the present invention includes the developing device described above and an image forming unit that forms an image on a recording medium using toner supplied from the developing device.

  In this configuration, as described above, the mixture of the toner and the developer is sufficiently stirred by the developing device, so that the electrostatic latent image is charged on the photosensitive drum on which the electrostatic latent image is formed from the developing roller. An exact amount of toner according to the amount adheres. As a result, an accurate image is formed on the recording medium by the toner attached according to the electrostatic latent image.

  The image forming apparatus according to the present invention further includes a developing device for each of a plurality of types of toner that performs different coloring, and includes an image forming unit that forms a color image with the toner of each color supplied from each developing device. It is characterized by having prepared.

  In this configuration, the above-described configuration is realized by a plurality of developing devices that attach the toner of each color to the photosensitive drum, so that an accurate color image is formed on the recording medium by the toner attached according to the electrostatic latent image. The

  According to the present invention, since the toner is agitated and mixed with the developer in the closed space opened only in the developer direction by the first blocking member, the toner is scattered in the photosensitive drum and the image forming apparatus. A developing device can be configured to prevent. Further, since the toner does not scatter, a developing device that reliably stirs and mixes the toner and the developer can be configured.

  In addition, according to the present invention, since the first blocking member has a shape extending below the average liquid level of the mixed solution, it is possible to prevent generation of toner that is scattered without being mixed with the developer. Furthermore, the stirring ability can be improved by the shearing force acting on the mixed liquid from the first blocking member.

  In addition, according to the present invention, the first blocking member has a shape that extends downward by a predetermined length (for example, 3 mm) or more from the average liquid level, so that the supply state of the developer and the mixture liquid to the developing roller Regardless of the supply state, the toner can be more reliably prevented from scattering and the stirring ability can be improved.

  Further, according to the present invention, a plurality of agitation rollers are arranged in parallel in a spiral shape, and the second blocking member is arranged between the agitation rollers, so that a flow path to the mixed liquid from the toner supply port to the developing roller is achieved. Can be taken for a long time, and the toner can be stirred and mixed with the developer more reliably.

  Further, according to the present invention, the third blocking member is arranged so as to block the mixed liquid flowing along the stirring roller, so that a shearing force acts on the mixed liquid by the third blocking member, and more The stirring ability can be further improved.

  In addition, according to the present invention, by using the above-described developing device, it is possible to reliably attach toner according to the electrostatic latent image formed on the photosensitive drum, so that the image formation that realizes an image clearly A device can be configured.

  In addition, according to the present invention, in the case of a color toner, since it has a smaller particle size, it is affected by the agitation and mixing effect described above. As a result, an image forming apparatus that realizes a clear color image more reliably can be configured.

  A developing device according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a side sectional view of the developing device according to the present embodiment.
2A is a plan view of the developing device according to the present embodiment, and FIG. 2B is a cross-sectional view taken along the line BB ′.
FIG. 3 is a side sectional view showing the AA ′ section shown in FIG. 2A of the developing device according to the present embodiment.
FIG. 4 is an external perspective view of the stirring roller used in the developing device according to the present embodiment.

  As shown in FIGS. 1 to 3, the developing device 1 is disposed on a housing 11, two stirring rollers 12 a and 12 b disposed in the housing 11, and an open surface of the housing 11 and is photosensitive. A developing roller 13 that abuts on the body drum 3 and a doctor blade 14 that has one end abutting on the developing roller 13 and the other end fixed to the end of the open surface of the housing. The housing 11 is provided with a toner supply port 50 to which the toner cut ridge 2 is connected on the open surface and the end side that opens. The toner supply port 50 is surrounded by a predetermined wall from the upper wall of the housing 11. Ribs 15 extending downward in length are formed. In addition, a partition plate 16 formed in a shape extending in the axial direction of the stirring rollers 12a and 12b is formed between the two stirring rollers 12a and 12b. Shielding plates 17a and 17b are installed at predetermined positions in the axial direction.

  Next, the structure of the developing device 1 will be specifically described.

  The casing 11 is a plan view in which the axial direction of the photosensitive drum 3 is the width direction, the surface facing the photosensitive drum 3 is an opening surface, and only the width in the vicinity of the opening surface is narrower than other portions. The shape is formed in a deformed substantially rectangular parallelepiped shape. The bottom wall portion of the housing 11 is composed of two semi-cylindrical portions, and these two semi-cylindrical portions are connected with the width direction of the housing 11 as a cylindrical length direction (direction perpendicular to the radial direction). It is formed in a shape. Inside the case 11 corresponding to the connection portions of these semi-cylindrical portions, both ends in the width direction do not reach the inner wall of the case 11, that is, both ends are separated from the inner wall in the width direction of the case 11 by a predetermined distance. A partition plate 16 having a length up to is formed. The partition plate 16 is formed in a shape that is connected to the upper inner wall and the lower inner wall of the housing 11 in the height direction. As a result, two rooms are formed in the housing 11 that pass only at a predetermined width at both ends in the width direction. The upper wall portion of the housing 11 has a substantially flat plate shape, and has a rectangular shape with a predetermined dimension in the vicinity of the end portion on the side facing the opening surface and the end portion on the side whose width is shortened in plan view. A toner supply port 50 is formed. Further, at a predetermined distance on the outer peripheral side of the toner supply port 50, a rib 15 is formed so as to surround the toner supply port 50 and project from the upper wall portion into the housing 11 by a predetermined length. The rib 15 has a thickness of about 1 mm to 3 mm, is made of a rigid body, and may have a predetermined flexibility. In the room on the side of the housing 11 that includes the toner supply port 50, shielding plates 17 a and 17 b that extend downward from the inner wall of the upper surface by a predetermined length are formed in order from the end on the toner supply port 50 side at predetermined intervals. These shielding plates 17a and 17b are also made of a rigid body like the ribs 15, and may have a predetermined flexibility. Here, the rib 15 corresponds to the “first shielding member” of the present invention, the partition plate 16 corresponds to the “second shielding member” of the present invention, and the shielding plates 17a and 17b correspond to the “third shielding member” of the present invention. Corresponds to “member”. The ribs 15 and the shielding plates 17a and 17b are formed in a shape that reaches below the average liquid level of the liquid in a state where a predetermined amount of developer described later is supplied into the housing 11, and more preferably. , Formed in a shape that extends 3 mm or more downward from the average liquid level.

  As shown in FIG. 4, the stirring rollers 12 a and 12 b have a spiral shape, and are installed in a direction in which the axial direction coincides with the width direction of the housing 11. Here, the stirring roller 12 a is disposed in a room on the toner supply port 50 side of the casing 11, and the stirring roller 12 b is disposed in a chamber on the photosensitive drum 3 side of the casing 11. The stirring rollers 12a and 12b are connected to each other by a gear 18 outside the casing 11, and the rotation directions of the stirring rollers 12a and 12b are reversed.

  The developing roller 13 is arranged on the opening surface of the housing 11 so that the axial direction thereof coincides with the width direction of the housing 11, that is, the axial direction coincides with the stirring rollers 12 a and 12 b. And it connects with the gear 18 outside the housing | casing 11 of the developing roller 13, and rotates in the opposite direction to the stirring roller 12a in the same direction as the stirring roller 12b.

  The doctor blade 14 is installed obliquely below the developing roller 13 on the opening surface of the housing 11, and the developer or the mixed solution of toner and developer supplied into the housing 11 is more than necessary. The developing roller 13 is in contact with the developing roller 13 at a predetermined angle so as not to adhere to the roller 13.

  The toner cartridge 2 includes a replenishing port having a replenishing roller 22 at one end, and includes a stirring blade 21 in a substantially central portion in the length direction, and the replenishing port including the replenishing roller 22 serves as a toner in the housing 11. It is connected to the supply port 50.

  In the developing device 1 and the toner cartridge 2 configured as described above, a mixed solution of toner and developer is supplied to the developing roller 13 as described below.

  First, the toner cartridge 2 supplies the toner to the casing 11 of the developing device 1 from the replenishing roller 22 provided at the replenishing port while rotating the stirring blade 21 to stir the toner held inside. When the toner is supplied from the toner supply port 50, the developing device 1 rotates the agitating rollers 12a and 12b, and first agitates together with the developer supplied in a predetermined amount into the housing 11 by the agitating roller 12a. And mix the toner with the developer. At this time, the presence of the ribs 15 causes the toner to exist only in the closed space surrounded by the upper inner wall of the housing 1, the ribs 15 and the developer, and does not scatter directly to the outside. Then, the toner and the developer in the closed space move while being stirred and mixed along the stirring roller 12a and flow to the outside of the rib 15. At this time, the rib 15 is formed so that the tip of the rib 15 is located at a position below the average liquid level of the developer, preferably at least 3 mm below the average liquid level. A shearing force is applied to the liquid so that the mixture is more easily stirred and mixed. Next, the mixed liquid thus stirred and mixed is partially dammed by the shielding plate 17a. As a result, the flow of the mixed liquid is changed and further mixed, and by passing through this portion, the shearing force from the shielding plate 17a acts to further mix. Next, the same flow and action occur in the shielding plate 17b, and the mixed liquid is further mixed. Next, the mixed liquid that has flowed to the end of the stirring roller 12a is guided to a room in which the stirring roller 12b is disposed through a path that passes between the chambers of the casing 11, and along the axial direction of the stirring roller 12b. The mixed liquid is supplied to the developing roller 13 while being stirred and mixed. In such a configuration, the flow distance of the mixed liquid in the housing 11 can be made longer than that of a conventional developing device including a single stirring roller. Thereby, the stirring performance is further improved, and the mixed liquid in which the toner is uniformly stirred and mixed can be supplied to the developing roller 13. In addition, since the shape that promotes stirring is formed at a plurality of positions and the stirring working distance can be extended with almost no change in the outer shape while having a simple structure, a developing device with extremely excellent stirring performance can be obtained. It can be configured in a small and simple structure.

  Next, an image forming apparatus according to a second embodiment will be described with reference to FIG.

  FIG. 5 is a configuration diagram showing a schematic configuration of the image forming apparatus according to the present embodiment.

  A document table 111 and an operation panel to be described later are provided on the upper surface of the image forming apparatus main body 100, and an image reading unit 110 and an image forming unit 210 are provided inside the image forming apparatus main body 100.

  A reversing automatic document feeder (RADF) 112 is mounted on the upper surface of the document table 111 so as to be openable and closable with respect to the document table 111 and having a predetermined positional relationship with respect to the surface of the document table 111. Has been.

Further, the double-sided automatic document feeder 112 first transports the original so that one side of the original faces the image reading unit 110 at a predetermined position on the original table 111, and after the image reading on the one side is completed. The document is reversed and conveyed toward the document table 111 so that the other side faces the image reading unit 110 at a predetermined position on the document table 111. The double-sided automatic document feeder 112 discharges the original after one-sided image reading for one original is completed, and executes a double-sided conveyance operation for the next original. The above document transport and front / back reversing operations are controlled in relation to the operation of the entire copying machine.

The image reading unit 110 is disposed below the document table 111 in order to read an image of the document conveyed on the document table 111 by the double-sided automatic document feeder 112. The image reading unit 110 includes document scanning bodies 113 and 114 that reciprocate in parallel along the lower surface of the document table 111, an optical lens 115, and a CCD line sensor 116 that is a photoelectric conversion element.

  The document scanning bodies 113 and 114 are composed of a first scanning unit 113 and a second scanning unit 114. The first scanning unit 113 includes an exposure lamp that exposes the surface of the document image and a first mirror that deflects a reflected light image from the document in a predetermined direction. While maintaining the distance, the robot moves back and forth in parallel at a predetermined scanning speed. The second scanning unit 114 includes second and third mirrors that deflect the reflected light image from the original deflected by the first mirror of the first scanning unit 113 further in a predetermined direction. It is reciprocated in parallel with one scanning unit 113 while maintaining a constant speed relationship.

  The optical lens 115 reduces the reflected light image from the original deflected by the third mirror of the second scanning unit, and forms the reduced light image at a predetermined position on the CCD line sensor 116.

  The CCD line sensor 116 sequentially photoelectrically converts the formed light image and outputs it as an electrical signal. The CCD line sensor 116 is a three-line color CCD that can read a black-and-white image or a color image and output line data separated into R (red), G (green), and B (blue) color components. . The document image information converted into an electrical signal by the CCD line sensor 116 is further transferred to the image processing unit 210 and subjected to predetermined image data processing.

  Next, the configuration of the image forming unit 210 and the configuration of each unit related to the image forming unit 210 will be described.

  Below the image forming unit 210, a paper feed mechanism 211 that separates sheets (recording media) P stacked and accommodated in a paper tray one by one and supplies them to the image forming unit 210 is provided. The sheets P separated and supplied one by one are transported to the image forming unit 210 with timing controlled by a pair of registration rollers 212 disposed in front of the image forming unit 210. Further, the paper P on which an image is formed on one side is re-supplied and conveyed to the image forming unit 210 in synchronization with the image formation of the image forming unit 210.

  A transfer conveyance belt mechanism 213 is arranged below the image forming unit 210. The transfer conveyance belt mechanism 213 is configured to convey the paper P by electrostatically adsorbing the transfer conveyance belt 216 stretched between the driving roller 214 and the driven roller 215 so as to extend substantially in parallel. A pattern image detection unit is provided adjacent to the lower side of the transfer conveyance belt 216.

  Further, a fixing device 217 for fixing the toner image transferred and formed on the paper P onto the paper P is disposed on the downstream side of the transfer and transport belt mechanism 213 in the paper transport path. The paper P that has passed through the nip between the pair of fixing rollers of the fixing device 217 is discharged onto a paper discharge tray 220 attached to the outer wall of the copier body 1 by a discharge roller 219 through a conveyance direction switching gate 218. The

The switching gate 218 selectively switches the conveyance path of the paper P after fixing between a path for discharging the paper P to the copying machine main body 1 and a path for resupplying the paper P toward the image forming unit 210. Is. The paper P whose transport direction has been switched again toward the image forming unit 210 by the switching gate 218 is turned upside down via the switchback transport path 221 and then supplied again to the image forming unit 210.

Further, above the transfer conveyance belt 216 in the image forming unit 210, in close proximity to the transfer conveyance belt 216, the first image forming station Pa, the second image forming station Pb, the third image forming station Pc, and The fourth image forming stations Pd are arranged in order from the upstream side of the sheet conveyance path.

The transfer / conveying belt 216 is frictionally driven by the driving roller 214 in the direction indicated by the arrow Z in FIG. 5 to carry the paper P fed through the paper feeding mechanism 211 as described above. Convey sequentially to Pd.

  Each of the image stations Pa to Pd has substantially the same configuration. Each of the image stations Pa, Pb, Pc, and Pd includes photosensitive drums 222a, 222b, 222c, and 222d that are driven to rotate in the direction of arrow F shown in FIG.

  Around each of the photosensitive drums 222a to 222d, there are chargers 223a, 223b, 223c, and 223d for uniformly charging the photosensitive drums 222a to 222d, and electrostatic latent images formed on the photosensitive drums 222a to 222d. Developing devices 224a, 224b, 224c, and 224d that respectively develop the images; transfer dischargers 225a, 225b, 225c, and 225d that transfer the developed toner images on the photosensitive drums 222a to 222d to the paper P; Cleaning devices 226a, 226b, 226c, and 226d that remove toner remaining on the drums 222a to 222d are sequentially arranged along the rotation direction of the photosensitive drums 222a to 222d.

Laser beam scanner units 227a, 227b, 227c, and 227d are provided above the respective photosensitive drums 222a to 222d. The laser beam scanner units 227a to 227d are a semiconductor laser element (not shown) that emits dot light modulated according to image data, and a polygon mirror (deflection) for deflecting the laser beam from the semiconductor laser element in the main scanning direction. Device) 240 and an fθ lens 241 and mirrors 242 and 243 for forming an image of the laser beam deflected by the polygon mirror 240 on the surface of the photosensitive drums 222a to 222d.

The laser beam scanner 227a has a pixel signal corresponding to the black component image of the color original image, the laser beam scanner 227b has a pixel signal corresponding to the cyan component image of the color original image, and the laser beam scanner 227c has a color original image. The pixel signal corresponding to the magenta color component image is input to the laser beam scanner 227d, and the pixel signal corresponding to the yellow color component image of the color original image is input to the laser beam scanner 227d.

Thereby, electrostatic latent images corresponding to the color-converted document image information are formed on the respective photosensitive drums 222a to 222d. The developing device 227a contains black toner, the developing device 227b contains cyan toner, the developing device 227c contains magenta toner, and the developing device 227d contains yellow toner. The electrostatic latent images on the photosensitive drums 222a to 222d are developed with the toners of these colors. As a result, the document image information color-converted by the image forming unit 210 is reproduced as a toner image of each color.

Further, a sheet adsorbing charger 228 is provided between the first image forming station Pa and the sheet feeding mechanism 211. The adsorbing charger 228 charges the surface of the transfer conveyance belt 216 to supply the sheet. The paper P supplied from the mechanism 211 is transported without being shifted between the first image forming station Pa and the fourth image forming station Pd in a state where the paper P is reliably adsorbed on the transfer transport belt 216.

On the other hand, a static eliminator 229 is provided almost directly above the drive roller 214 between the fourth image station Pd and the fixing device 217. An AC current for separating the sheet P electrostatically attracted to the transport belt 216 from the transfer transport belt 216 is applied to the static eliminator 229.

  In the color image forming apparatus having the above configuration, cut sheet-like paper is used as the paper P. When the paper P is fed out from the paper feed cassette and supplied into the guide of the paper feed conveyance path of the paper feed mechanism 211, the leading end of the paper P is detected by a sensor (not shown). Is temporarily stopped by the pair of registration rollers 212 on the basis of the detection signal output from.

  Then, the paper P is sent onto the transfer conveyance belt 216 rotating in the direction of the arrow Z in FIG. 5 in time with the image stations Pa to Pd. At this time, the transfer conveyance belt 216 is charged by the charging charger 228 as described above, so that the sheet P is stably conveyed and supplied while passing through the image stations Pa to Pd. .

In each of the image stations Pa to Pd, a toner image of each color is formed and superimposed on the support surface of the paper P that is electrostatically attracted and transported by the transfer transport belt 216. When the transfer of the image by the fourth image station Pd is completed, the paper P is sequentially peeled off from the transfer conveyance belt 216 from the leading end portion thereof by the discharger for discharging, and guided to the fixing device 217. Finally, the paper P on which the toner image is fixed is discharged onto a paper discharge tray 220 from a paper discharge port (not shown).

  In such a color image forming apparatus, the developing device shown in the first embodiment is applied. That is, the developing device 1 shown in the first embodiment is applied to each of the developing devices 224a to 224d shown in the present embodiment. At this time, the photosensitive drum 3 shown in the first embodiment corresponds to the photosensitive drums 222a to 222d of the present embodiment.

  By applying such a developing device, toner of an amount corresponding to the electrostatic latent image is reliably supplied to the photosensitive drums 222a to 222d. Further, since the stirring and mixing in the developing device is sufficient, it is possible to prevent the toner from being released from the developing solution and adhering to the photosensitive drums 222a to 222d or scattering into the image forming apparatus. Accordingly, it is possible to configure an image forming apparatus that does not cause image contamination due to unnecessary toner and that reliably forms an image. In the above description, the color image forming apparatus has been described. However, the same configuration can be applied to the monochrome image forming apparatus, and the same effect can be obtained. Since the color toner is often smaller in the toner diameter than the monochrome toner, the color image forming apparatus having the structure shown in the present embodiment using the developing device having the above-described structure is more monochrome. The obtained effect is higher than that of the image forming apparatus.

  In the above description, the image forming apparatus has been described in which laser beam scanner units 227a to 227d scan and expose a laser beam to perform optical writing on the photosensitive member. However, instead of the laser beam scanner unit, a writing optical system (LED head) including a light emitting diode array and an imaging lens array may be used. The LED head is smaller than the laser beam scanner unit and has no moving parts and is silent. As described above, the above-described configuration can be suitably used in an image forming apparatus such as a tandem digital color copying machine that requires a plurality of optical writing units.

1 is a side sectional view of a developing device according to a first embodiment. FIG. 2 is a plan view of the developing device according to the first embodiment and a B-B ′ plan sectional view thereof. Side surface sectional view which shows the A-A 'cross section shown to Fig.2 (a) of the image development apparatus concerning this embodiment. FIG. 3 is an external perspective view of a stirring roller used in the developing device according to the first embodiment. 1 is a configuration diagram showing a schematic configuration of an image forming apparatus according to a second embodiment. It is side surface sectional drawing which shows the structure of the conventional image development apparatus and a toner cut ridge. 2 is a side cross-sectional view illustrating a schematic configuration of a developing device described in Patent Document 1. FIG.

Explanation of symbols

1-developing device 11-casing 12a, 12b-stirring roller 13-developing roller 14-doctor blade 15-rib 16-partition plates 17a, 17b-shielding plate 50-toner supply port

Claims (7)

In a developing device including a stirring roller that stirs toner and developer supplied from a toner supply port into a housing and supplies the developer to the surface of the developing roller.
The housing includes a first shielding member that forms a predetermined space that opens only in the direction of the stirring roller in the vicinity of the toner supply port and restricts the flow of toner and developer in the direction of the developing roller. A developing device.   The developing device according to claim 1, wherein the first shielding member has a shape extending from an inner wall on the upper surface side of the housing to at least a lower side than the average liquid surface.   3. The developing device according to claim 2, wherein the first shielding member has a shape extending from the average liquid level to the lower side by 3 mm or more. The housing includes a plurality of stirring rollers each having a spiral shape between the toner supply port and the developing roller,
The developing device according to claim 1, further comprising a second shielding member extending in parallel with an axial direction of the stirring roller between the plurality of stirring rollers.   5. The housing includes a plurality of third blocking members that regulate the flow of the toner and the developer between the toner supply port and the downstream end of the toner and the developer of the second blocking member. The developing device according to 1. A developing device according to claim 1;
An image forming apparatus comprising: an image forming unit configured to form an image on a recording medium with toner supplied from the developing device. The developing device is provided for each color of a plurality of toners that perform different coloring,
The image forming apparatus according to claim 6, further comprising the image forming unit configured to form a color image with toner of each color supplied from each developing device.

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