JP6379926B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus.

  For developing devices that develop a latent image on the surface of an image carrier into a visible image, techniques described in Patent Documents 1 to 3 below are known.

  In Japanese Patent Application Laid-Open No. 05-150634 as Patent Document 1, a suction portion (11) is provided at a position downstream of the developing roller (81) with respect to the rotation direction of the photoconductor (9). 11) A suction port (4) is provided with a toner collecting electrode (2) for electrically collecting floating toner, and a suction duct (12) to which the suction portion (11) is connected. A technique is described in which a fan (13) is provided, and the toner repaired by the toner collecting electrode (2) is sucked by the fan (13). In the configuration described in Patent Document 1, suction is performed by the suction port portion (4) having a width corresponding to the entire width direction of the photoconductor (9), and the center of the photoconductor (9) in the width direction is separated from the photoconductor (9). The floating toner is collected at the center in the width direction by the partition plate (16) inclined in the direction and is conveyed rearward by the connecting pipe (15) extending from the center in the width direction to the axial direction of the photoreceptor (9).

  In Japanese Patent Application Laid-Open No. 11-161119 as Patent Document 2, the air inlet (5) of the duct (4) is disposed downstream of the developing sleeve (3) with respect to the rotation direction of the photosensitive drum (1). A technique for sucking and collecting floating developer from an air inlet (5) by an air intake means (11) connected to a duct (4) is described. In the technique described in Patent Document 2, the duct (4) extends along the axial direction of the photosensitive drum (1), and is sucked from the one end side of the duct (4) by the suction means (11).

  In Japanese Patent Application Laid-Open No. 2010-151933 as Patent Document 3, a suction opening (31e) for sucking scattered toner is provided in the vicinity of the end of the developing device (31), and in the vicinity of the central portion of the developing device (31). A configuration is described in which a discharge opening (31f) is provided, and the scattered toner sucked by the suction opening (31e) is transported to the discharge opening (31f) through the transport path (31g) and discharged. In the configuration described in Patent Document 3, the discharge opening (31f) is connected to the air suction port (44) of the cleaning device (40) of the adjacent image forming unit (11), and the housing of the cleaning device (40). The air is exhausted by the exhaust fan (50) connected to the tip of the air discharge port (45) formed in (41).

JP 05-150634 A (“0010” to “0012”, “0015” to “0020”, FIGS. 1 and 2) JP-A-11-161119 ("0015" to "0020", FIGS. 1 and 2) JP 2010-151933 A ("0039" to "0054", FIGS. 3 to 6 and FIG. 12)

  It is a technical object of the present invention to suppress the leakage of the developer while suppressing leakage of the floating developer.

In order to solve the technical problem, the developing device of the invention according to claim 1 comprises:
A developer holding body disposed on the surface, facing the image holding body, and rotated while holding the developer;
A first opening disposed downstream of the developer holder relative to the rotation direction of the image carrier and capable of sucking the floating developer;
A flow path connected to the first opening;
A suction device connected to the flow path for sucking a gas;
A leakage preventing member disposed downstream of the first opening with respect to the rotation direction of the image carrier, and preventing leakage of the developer;
A second opening disposed in a space between the leakage preventing member and the first opening and connecting the flow path;
The second opening disposed downstream of the first opening and upstream of the leakage preventing member with respect to the rotation direction of the image carrier;
A third opening disposed upstream of the second opening and downstream of the first opening with respect to the rotation direction of the image carrier;
The first opening partitioned at a predetermined interval with respect to the axial direction of the developer holder;
With
With respect to the axial direction of the developer holder, the distance between the end partition on the other end side of the first opening and the end wall is L1, and the axial length of the second opening is L2. When the length of the third opening in the axial direction is L3, L1>L2> L3 is set .

The invention according to claim 2 is the developing device according to claim 1,
The flow path extending along the axial direction of the developer holder;
The suction device connected to one end of the flow path in the axial direction and sucking gas;
In the space between the leakage prevention member and the first opening, the second opening disposed corresponding to the other end side of the flow path;
It is provided with.

In order to solve the technical problem, an image forming apparatus according to claim 3 is provided.
An image carrier,
A latent image forming apparatus for forming a latent image on the surface of the image carrier;
The developing device according to claim 1 or 2 , wherein a latent image on the surface of the image carrier is developed into a visible image;
A transfer device for transferring a visible image of the surface of the image carrier to a medium;
A fixing device for fixing a visible image on the surface of the medium;
It is provided with.

According to the first and third aspects of the invention, the floating developer leaks as compared with the configuration in which the second opening is not provided corresponding to the space between the leakage preventing member and the first opening. It is possible to suppress the developer from falling down while suppressing the above.
Further, according to the first and third aspects of the present invention, the generation of vortices in the space between the leakage preventing member and the first opening can be further suppressed as compared with the case where the third opening is not provided.
Further, according to the first and third aspects of the invention, compared to the case where L1>L2> L3 is not set, the loss of the suction performance of the first opening is reduced, and leakage of the second opening is achieved. The loss of the suction capability in the space between the prevention member and the first opening is also reduced.
According to the second aspect of the present invention, the developer can be suppressed while suppressing the enlargement of the developing device as compared with the case where the suction device is connected to one end side and the second opening is not formed on the other end side. Can also be suppressed.

FIG. 1 is an explanatory diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of the developing device according to the first embodiment. 3 is a view as seen from the direction of arrow III in FIG. FIG. 4 is a plan view of the flow path forming member of the first embodiment. FIG. 5 is an explanatory view of a gas flow in a conventional developing device. FIG. 6 is an explanatory diagram of a gas flow in the developing device of the first embodiment. FIG. 7 is an explanatory diagram of the gas flow when the upper vent is not provided in the developing device of the first embodiment.

Next, specific examples of embodiments of the present invention (hereinafter referred to as examples) will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.
In the following description using the drawings, illustrations other than members necessary for the description are omitted as appropriate for easy understanding.

FIG. 1 is an explanatory diagram of an image forming apparatus according to a first embodiment of the present invention.
In FIG. 1, a copying machine U as an example of an image forming apparatus according to the first exemplary embodiment is an example of a main body of an image forming apparatus, and includes a printer unit U1 as an example of an image recording apparatus. A scanner unit U2 as an example of a reading unit and an example of an image reading device is supported on the upper portion of the printer unit U1. An auto feeder U3 as an example of a document transport device is supported on the upper portion of the scanner unit U2. The scanner unit U2 of the first embodiment supports a user interface U0 as an example of an input unit. The user interface U0 can be operated by the operator by inputting the user interface U0.
A post-processing device U4 is arranged on the right side of the printer unit U1.

  A document tray TG1 as an example of a medium container is disposed on the upper part of the auto feeder U3. A plurality of documents Gi to be copied can be stacked and stored in the document tray TG1. A document discharge tray TG2 as an example of a document discharge unit is formed below the document tray TG1. A document transport roll U3b is disposed between the document tray TG1 and the document discharge tray TG2 along the document transport path U3a.

A platen glass PG as an example of a transparent document table is disposed on the upper surface of the scanner unit U2. In the scanner unit U2 of the first embodiment, a reading optical system A is disposed below the platen glass PG. The optical system A for reading in Example 1 is supported so as to be movable in the left-right direction along the lower surface of the platen glass PG. The reading optical system A is normally stopped at the initial position shown in FIG.
On the right side of the optical system A for reading, an imaging element CCD as an example of an imaging member is arranged. An image processing unit GS is electrically connected to the image sensor CCD.
The image processing unit GS is electrically connected to the control unit C and the writing circuit D of the printer unit U1. The writing circuit D is electrically connected to Y: yellow, M: magenta, C: cyan, K: black exposure devices ROSy, ROSm, ROSc, ROSK.

In FIG. 1, photosensitive drums Py, Pm, Pc, and Pk as examples of an image holding member are disposed below exposure apparatuses ROSy to ROSk as examples of a latent image forming apparatus.
Around the photosensitive drum Pk for K color, along the rotation direction of the photosensitive drum Pk, a charger CRk, a developing device Gk, a primary transfer roll T1k as an example of a primary transfer device, and an image carrier A drum cleaner CLk as an example of a cleaner is disposed.
A charging voltage for charging the photosensitive drum Pk is applied from the power supply circuit E to the charger CRk. The developing device Gk includes a developing roll R0 as an example of a developer holding body. A developing voltage is applied from the power supply circuit E to the developing roll R0. A primary transfer voltage having a polarity opposite to the charging polarity of the developer is applied from the power supply circuit E to the primary transfer roll T1k.

In the first embodiment, the photosensitive drum Pk, the charger CRk, and the drum cleaner CLk are unitized as an image carrier unit UK. The image carrier unit UK is detachably supported with respect to the printer unit U1.
For each of the colors Y, M, and C, image carrier units UY, UM, and UC configured similarly to the K color are provided. Therefore, each image carrier unit UY, UM, UC also includes photosensitive drums Py, Pm, Pc, chargers CRy, CRm, CRc, and drum cleaners CLy, CLm, CLc.
In the first exemplary embodiment, the developing devices Gy to Gk are also unitized and supported to be detachable from the printer unit U1.
The respective image carrier units UY, UM, UC, UK and developing devices Gy, Gm, Gc, Gk constitute toner image forming members UY + Gy, UM + Gm, UC + Gc, UK + Gk.

A belt module BM as an example of an intermediate transfer device is disposed below the image carrier units UY to UK. The belt module BM includes an intermediate transfer belt B as an example of an intermediate transfer member, belt support rolls Rd, Rt, Rw, Rf, T2a as examples of support members of the intermediate transfer member, and primary transfer rolls T1y, T1m. , T1c, T1k. Belt support rolls Rd, Rt, Rw, Rf, and T2a include a belt drive roll Rd as an example of a drive member, a tension roll Rt as an example of a tension applying member, a walking roll Rw as an example of a meandering prevention member, and a driven member A plurality of idler rolls Rf as an example and a backup roll T2a as an example of a counter member for secondary transfer are included.
The intermediate transfer belt B is supported by the belt support rolls Rd, Rt, Rw, Rf, T2a so as to be rotatable in the direction of the arrow Ya.

  Below the backup roll T2a, a secondary transfer unit Ut as an example of a medium transport device is disposed. The secondary transfer unit Ut is an example of a secondary transfer member, and includes a secondary transfer roll T2b as an example of a second transport member. The secondary transfer roll T2b is supported by the backup roll T2a so as to be separated and in contact with an intermediate transfer belt B as an example of a first conveying member. An area where the secondary transfer roll T2b is in contact with the intermediate transfer belt B forms a secondary transfer area Q4 which is an example of a transfer area and an example of a counter area. Further, a contact roll T2c as an example of a contact member for applying a voltage is in contact with the backup roll T2a. A secondary transfer voltage having the same polarity as the toner charging polarity is applied to the contact roll T2c from the power supply circuit E at a preset time. The rolls T2a to T2c constitute a secondary transfer device T2.

A belt cleaner CLB as an example of an intermediate transfer member cleaner is disposed on the downstream side of the secondary transfer region Q4 with respect to the rotation direction of the intermediate transfer belt B.
The primary transfer rolls T1y to T1k, the intermediate transfer belt B, the secondary transfer unit T2, the belt cleaner CLB, and the like constitute a transfer device T1 + B + T2 + CLB that transfers the image on the surface of the photosensitive drums Py to Pk onto the sheet S.

Under the printer unit U1, paper feed trays TR1 to TR3 as an example of a medium storage unit are supported so as to be able to enter and exit. The sheet feeding trays TR1 to TR3 store sheets S as an example of a medium.
A pickup roll Rp as an example of a medium take-out member is disposed on the upper left side of each of the paper feed trays TR1 to TR3. On the left side of the pick-up roll Rp, a separating roll Rs as an example of a separating member is disposed.
On the left side of each of the paper feed trays TR1 to TR3, a medium transport path SH1 extending upward is formed. A plurality of transport rolls Ra as an example of a medium transport member are arranged in the transport path SH1.
In the transport path SH1, a registration roll Rr as an example of a feeding member is disposed on the downstream side in the transport direction of the sheet S and on the upstream side of the secondary transfer region Q4.

A registration guide SGr as an example of a medium guide member and a sheet guide SG1 before transfer are sequentially arranged on the downstream side of the registration roll Rr with respect to the conveyance direction of the sheet S.
A post-transfer sheet guide SG2 as an example of a medium guide member is disposed on the downstream side of the secondary transfer region Q4 with respect to the conveyance direction of the sheet S. A conveyance belt BH as an example of a medium conveyance member is disposed on the downstream side of the sheet guide SG2 after transfer with respect to the conveyance direction of the sheet S.
A fixing device F is disposed on the downstream side of the conveyance belt BH with respect to the conveyance direction of the sheet S. The fixing device F includes a heating roll Fh as an example of a heat fixing member and a pressure roll Fp as an example of a pressure fixing member. A fixing region Q5 is formed by a region where the heating roll Fh and the pressure roll Fp are in contact with each other.

A discharge path SH3 as an example of a medium transport path is formed on the downstream side of the fixing device F with respect to the transport direction of the sheet S. The discharge path SH3 extends rightward toward the post-processing device U4. A transport roll Rb as an example of a medium transport member is disposed at the downstream end of the discharge path SH3. An upstream end of a reversing path SH4 as an example of a medium transport path is connected to the downstream end of the discharge path SH3. The reversing path SH4 according to the first embodiment joins the conveyance path SH1 on the upstream side of the registration roll Rr through the space below the secondary transfer unit Ut and above the uppermost sheet feed tray TR1. A plurality of transport rolls Ra as an example of a medium transport member are arranged on the reversing path SH4.
A first gate GT1 as an example of a transfer path switching member is disposed at a branch portion between the discharge path SH3 and the reversal path SH4.

The post-processing device U4 has a processing path SH5 as an example of a medium transport path. In the processing path SH5, a plurality of transport rolls Rb as an example of a medium transport member are arranged. In addition, the conveyance roll Rb of Example 1 is comprised so that normal / reverse rotation is possible. A decurler U4a as an example of a curvature correction device is disposed in the processing path SH5. The decurler U4a according to the first embodiment includes a first curl correction member h1 and a second curl correction member h2 as examples of a curvature correction member.
A discharge roll Rh as an example of a discharge member is disposed on the downstream side of the decurler U4a with respect to the conveyance direction of the sheet S. A discharge tray TH1 as an example of a discharge unit is disposed on the downstream side of the discharge roll Rh with respect to the conveyance direction of the sheet S. The discharge tray TH1 according to the first exemplary embodiment is supported to be movable in the vertical direction according to the stacking amount of the sheets S.
The medium transport path SH of the first embodiment is configured by the elements having the symbols SH1 to SH5. Further, a medium transport system SU is constituted by the elements having the symbols SH, Ra, Rb, Rr, Rh, SGr, SG1, SG2, BH, GT1 and the like.

(Description of image forming operation)
In FIG. 1, in the copying machine U according to the first embodiment, when a copy start key is input on the user interface U0, the scanner unit U2 reads a document.
When the automatic feeder U3 is used to automatically convey and copy a document, each document that sequentially passes through the reading position on the platen glass PG with the reading optical system A stopped at the initial position. Gi is exposed. Accordingly, the plurality of documents Gi stored in the document tray TG1 sequentially pass through the document reading position on the platen glass PG and are discharged to the document discharge tray TG2.
When the operator places the document Gi on the platen glass PG by hand, the optical system A for reading moves in the left-right direction, and the document on the platen glass PG is scanned while being exposed.

The reflected light from the original document Gi passes through the optical system A for reading and is condensed on the image sensor CCD. The image pickup device CCD converts the reflected light of the original collected on the image pickup surface into an electric signal.
The image processing unit GS converts the read signal input from the image sensor CCD into a digital image signal and outputs the digital image signal to the writing circuit D of the printer unit U1. The writing circuit D outputs a laser drive signal corresponding to image information of Y: yellow, M: magenta, C: cyan, and K: black input from the image processing unit GS at a preset time. Are output to the exposure apparatuses ROSy, ROSm, ROSc, and ROSk of the respective colors as an example.
The control unit C outputs a signal for controlling the timing when the writing circuit D outputs a signal, the power supply circuit E, and the like.

  The surfaces of the photosensitive drums Py to Pk are charged by the chargers CRy to CRk, respectively. On the photosensitive drums Py to Pk whose surfaces are charged, electrostatic latent images are formed by laser beams Ly, Lm, Lc, and Lk as an example of writing light output from the exposure apparatuses ROSy to ROSk. The electrostatic latent images on the surfaces of the photosensitive drums Py to Pk are converted into toner images as examples of visible images of Y: yellow, M: magenta, C: cyan, and K: black by the developing devices Gy to Gk. Developed.

The toner images on the surfaces of the photosensitive drums Py to Pk are transferred onto the intermediate transfer belt B by primary transfer rolls T1y to T1k. When a multicolor image, that is, a so-called color image is formed, the toner images on the photosensitive drums Py to Pk are sequentially transferred to the intermediate transfer belt B in a superimposed manner. In the case of only black image data, only the black toner image is formed using only the K: black photosensitive drum Pk and the developing device Gk. Accordingly, only the black toner image is transferred to the intermediate transfer belt B.
After the primary transfer, the toner remaining on the surface of the photosensitive drums Py to Pk is cleaned by the drum cleaners CLy to CLk.
The toner image transferred to the intermediate transfer belt B is conveyed to the secondary transfer area Q4.

  The sheets S of the respective trays TR1 to TR3 are taken out by the pickup roll Rp at a preset sheet feeding time. The sheets S picked up by the pick-up roll Rp are separated one by one by the rolling roll Rs when picked up in a state where a plurality of sheets S are overlapped. The sheet S that has passed the separating roll Rs is conveyed to the registration roll Rr by a plurality of conveying rolls Ra.

The registration roll Rr sends out the sheet S in accordance with the time when the toner image is conveyed to the secondary transfer region Q4. The sheet S sent out by the registration roll Rr is guided by the guides SGr and SG1 and conveyed to the secondary transfer region Q4.
The toner image on the intermediate transfer belt B is transferred to the sheet S by the secondary transfer unit T2 when passing through the secondary transfer region Q4. In the case of a color image, the toner images primarily transferred onto the surface of the intermediate transfer belt B are secondarily transferred to the sheet S at once.
The intermediate transfer belt B after passing through the secondary transfer region Q4 is cleaned of residual toner by a belt cleaner CLB.

The sheet S on which the toner image is secondarily transferred is conveyed to the fixing device F through a medium guide member SG2 after transfer and a conveyance belt BH as an example of a medium conveyance member before fixing. The toner image on the surface of the sheet S is heated and fixed by the fixing device F when passing through the fixing region Q5. The sheet S on which the toner image is heated and fixed in the fixing area Q5 is conveyed through the discharge path SH3.
When the sheet S is discharged to the discharge tray TH1, the sheet S conveyed through the discharge path SH3 is carried into the processing path SH5 of the post-processing device U4. The switching gate h3 switches the conveyance destination to the first curl correction member h1 or the second curl correction member h2 in accordance with the curvature of the sheet S conveyed to the processing path SH5, the so-called curl direction. The curl correction members h1 and h2 correct the curl of the sheet S that passes therethrough. The sheet S with the curl corrected is discharged to the discharge tray TH1 by the discharge roll Rh.

  When the sheet S is printed on both sides, the first gate GT1 switches the conveyance destination of the sheet S to the reversing path SH4 after the rear end of the sheet S passes through the first gate GT1. And the conveyance roll Rb of the downstream end of discharge path SH3 and the conveyance roll Rb of process path SH5 reversely rotate. Accordingly, the sheet S that has passed through the first gate GT1 is carried into the reversing path SH4 in a state where the transport direction is reversed by the transport roll Rb. That is, the sheet S is switched back. The switched-back sheet S is conveyed through the reversing path SH4 and conveyed to the registration roll Rr with the front and back sides reversed.

(Description of developing device)
FIG. 2 is an explanatory diagram of the developing device according to the first embodiment.
Next, the developing devices Gy, Gm, Gc, and Gk according to the first embodiment of the present invention will be described. Since the developing devices Gy, Gm, Gc, and Gk of the respective colors are configured in the same manner, the development of the Y color is performed. Only the apparatus Gy will be described in detail, and detailed descriptions of the other color developing apparatuses Gm, Gc, Gk will be omitted.
In FIG. 2, the developing device Gy arranged to face the photosensitive drum Py has a developing container V that stores a two-component developer containing toner and a carrier. The developing container V has a lower container body 1. A container cover 2 as an example of a lid member is supported on the upper part of the container body 1. The container cover 2 closes the upper surface of the container body 1.

The developing container main body 1 is formed with a developing roll chamber 4 as an example of a housing portion for a developer holding body in the upper left portion of the inside. A supply chamber 6 as an example of a first storage chamber is formed below the developing roll chamber 4. The supply chamber 6 is connected to the developing roll chamber 4. On the right side of the supply chamber 6, a stirring chamber 7 as an example of a second storage chamber is formed.
The supply chamber 6 and the stirring chamber 7 are partitioned by a partition wall 8 as an example of a partition member.

  The developing roll chamber 4 accommodates a developing roll R0y as an example of a developer holding body. The developing roll R0y has a part of the upper left outer surface disposed so as to face the photosensitive drum Py. The developing roll R0y has a magnet roll 11 as an example of a magnet member. The magnet roll 11 is supported by the developing container V so as not to rotate. On the outer periphery of the magnet roll 11, a developing sleeve 12 as an example of a rotating body is disposed. The developing sleeve 12 is rotatably supported by the developing container V. In the developing device Gy of Example 1, the developing sleeve 12 rotates in the same direction as the moving direction of the surface of the photosensitive drum Py in the developing region Q2y.

Above the developing roll chamber 4, a trimmer 13 as an example of a regulating member having a layer thickness is disposed. The trimmer 13 is supported with a predetermined gap with respect to the developing sleeve 12.
3 and 4, a supply auger 16 as an example of a first conveying member is disposed in the supply chamber 6. In the stirring chamber 7, a stirring auger 17 as an example of a second transport member is disposed.

3 is a view as seen from the direction of arrow III in FIG.
FIG. 4 is a plan view of the flow path forming member of the first embodiment.
In FIG. 2, the developing container V has a flow path forming member 21 supported at the lower part of the container body 1. 2 to 4, the flow path forming member 21 has a plate-like flat portion 22 that faces the lower surface of the container body 1. It is supported on the lower surface of the container body 1 at the right end of the flat portion 22 and the edge portions 22a at both front and rear ends. The flat portion 22 is supported with a gap from the lower surface of the container body 1 at a portion other than the edge portion 22a.
A left wall portion 23 is integrally formed at the left end of the flat portion 22. An upper surface 23 a of the left wall portion 23 extends obliquely upward to the left along the lower surface of the container body 1. The upper surface 23 a of the left wall portion 23 of the first embodiment is disposed in a state where a gap is opened with respect to the lower surface of the container body 1.

3 and 4, an exhaust part 24 is formed at the rear end of the flow path forming member 21. A fan 26 as an example of a suction device is connected to the exhaust unit 24.
2 to 4, as an example of the flow path, the space surrounded by the upper surface of the flat portion 22 and the upper surface 23a of the left wall portion 23, the lower surface of the container body 1, and the front and rear edges and the right edge. The duct 31 is configured. A main air inlet 32 as an example of a first opening is formed at the end of the upper surface 23a of the left wall portion 23 on the photosensitive drum Py side. Therefore, when the fan 26 is operated, gas is sucked from the main air inlet 32 and gas is exhausted from the exhaust unit 24 to the outside of the developing device Gy through the duct 31.

  3 and 4, the left wall portion 23 of the first embodiment is formed with partition walls 36 at both ends in the front-rear direction, which is the axial direction of the developing roll R0y. Therefore, the partition wall 36 divides the front and rear end portions of the main air inlet 32 extending in the front-rear direction.

In FIG. 2, a base end of a film seal 41 as an example of a leakage preventing member is supported on the lower end 23 b of the left wall portion 23. The film seal 41 is made of a thin film resin. The tip of the film seal 41 is disposed in the state of being close to the surface of the photosensitive drum Py.
Therefore, as shown in FIG. 2, in the first embodiment, the downstream space 42 of the development region Q2y is constituted by the space surrounded by the left surface 23c of the left wall 23, the surface of the photosensitive drum Py, and the film seal 41. ing.

2 to 4, a lower vent 46 as an example of a second opening is formed in the left wall portion 23 of the first embodiment corresponding to the lower portion of the downstream space 42. The lower vent 46 penetrates the left wall portion 23 to the left and right to connect the downstream space 42 and the duct 31.
Further, an upper vent 47 as an example of a third opening is formed in the upper portion of the downstream space 42. Similar to the lower vent 46, the upper vent 47 penetrates the left wall portion 23 to the left and right to connect the downstream space 42 and the duct 31.

In FIG. 4, in Example 1, the width L2 in the front-rear direction of the lower vent 46 is set to be larger than the width L3 in the front-rear direction of the upper vent 47. In the first embodiment, the width L2 in the front-rear direction of the lower vent 46 is set to be smaller than the width L1 between the front partition wall 36 and the front end face 32a of the main intake port 32.
In the first embodiment, (opening area of the main intake port 32)> (opening area of the lower ventilation port 46)> (opening area of the upper ventilation port 47) is set. In particular, in the first embodiment, (opening area of the main intake port 32)> (opening area of the lower ventilation port 46) + (opening area of the upper ventilation port 47) is set.

(Operation of developing device)
In the developing device Gy of Embodiment 1 having the above-described configuration, when the image forming operation is started, the developing rolls R0y to R0k and the augers 16 and 17 rotate. As the augers 16 and 17 rotate, the developer circulates between the circulation chambers 6 + 7 while being stirred. The developer in the supply chamber 6 is attracted to the developing sleeve 12 by magnetic force. When the developer adsorbed on the developing sleeve 12 passes through the trimmer 13, only a preset developer corresponding to the gap between the trimmer 13 and the developing sleeve 12 passes. Therefore, the developer that has passed through the trimmer 13 is in the form of a layer having a preset thickness. The developer that has passed through the trimmer 13 develops the latent images on the photosensitive drums Py to Pk in the development areas Q2y to Q2k. The developer not used for development is returned to the circulation chamber 6 + 7.

At the time of image formation, if an alternating voltage is applied as a developing agent or a developing voltage that is insufficiently charged in the developing region Q2y, the developer falls off the developing roll R0y or the photosensitive drum Py in the vicinity of the developing region Q2y. And may float.
If the floating developer is left as it is, there are problems such as adhering to the photosensitive drum Py and the recording sheet S, degrading the image quality, and staining the inside of the copying machine U. Correspondingly, like the techniques described in Patent Documents 1 to 3, the floating developer is sucked together with the gas on the downstream side of the development region Q2y.

  In the first embodiment, the film seal 31 is disposed on the downstream side of the development area Q2, and can receive the floating developer that cannot be completely sucked and the developer that has dropped off directly from the development area Q2y. Therefore, the leakage of the developer is reduced as compared with the configuration in which the film seal 31 is not provided.

FIG. 5 is an explanatory view of a gas flow in a conventional developing device.
In FIG. 5 and FIGS. 6 and 7 described later, the direction of the arrow corresponds to the direction of the gas flow, and the length of the arrow corresponds to the gas flow velocity.
In FIG. 5, in the conventional developing device, in the configuration in which the film seal 02 is disposed on the downstream side with respect to the main suction port 01, the air toward the main suction port 01 flows between the film seal 02 and the surface of the photoconductor 03. It flows through the gap. At this time, the air that has passed through the gap between the film seal 02 and the photoconductor 03 enters the space 06 between the film seal 02, the photoconductor 03, and the left wall portion 04. This space 06 is wider than the gap between the film seal 02 and the photoconductor 03, and the flow of air is weakened, and as shown in FIG. 5, a flow in which the vortex 07 is wound in the space 06 is formed.

Therefore, the floating developer dropped from the surface of the photoreceptor 03 in the space 06, the developer dropped directly from the development area Q2, and the developer scattered and floated when the photoreceptor drums Py to Pk collide with the intermediate transfer belt B. And the like are likely to stay in the form of being wound in the vortex 07 and hardly move toward the main suction port 01. Therefore, the developer tends to accumulate and accumulate in the space 06 over time. If the amount of accumulated developer increases, the developer may spill downward from the gap between the film seal 02 and the photoreceptor 03, and the image may be stained.
In particular, in the configuration in which gas is sucked from one end side of the developing device as in the technique described in Patent Document 2, the gas is discharged at the other end side away from the fan or the like compared to one end side near the suction device such as a fan or the like. The suction power becomes weak. Therefore, there is a problem that the developer is likely to accumulate on the other end side and is likely to spill compared to the one end side. Note that, as in the techniques described in Patent Documents 1 and 3, in the configuration in which the suction is performed from the main intake ports in the entire front-rear direction, which is the width direction of the developing device, and after being collected in the center in the front-rear direction, Since the arrangement for guiding the main intake port to the center is arranged, there is a problem that the size of the developing device in the left-right direction is increased.

FIG. 6 is an explanatory diagram of a gas flow in the developing device of the first embodiment.
On the other hand, in the first embodiment, the downstream space 42 is formed with a lower vent 46 connected to the duct 31. Therefore, as shown in FIG. 6, gas can be sucked directly into the duct 31 from the downstream space 42. Therefore, the vortex 07 in the space 06 is suppressed as compared with the conventional configuration in which the lower vent 46 is not provided. Therefore, compared to the conventional configuration in which the vortex 07 is formed, it is reduced that the developer spills.
In particular, in the developing device Gy of Example 1, the air is exhausted from the exhaust portion 24 at the rear end, and the front end where the suction force of the fan 26 is weakened while suppressing the size of the developing device Gy from increasing in the left-right direction. A lower air vent 46 is provided on the side to reduce developer spillage.

Here, if (width L2 of the lower vent 46)> (width L1 of the main inlet 32) or (open area of the lower vent 46)> (open area of the main inlet 32) The suction of the lower vent 46 tends to be more dominant than the suction of the main intake port 32, and the suction ability of the floating developer from the main intake port 32 may be reduced. On the other hand, in the first embodiment, L2 <L1, in particular, (opening area of the main intake port 32)> (opening area of the lower ventilation port 46) is set. Therefore, a reduction in the suction capacity from the main inlet 32 is also suppressed. As a result of experiments conducted by the present inventors, the effect of vortex elimination tends to be deeply related to the width in the axial direction, and the suction ability is considered to be deeply related to the opening area.
Further, if the lower vent 46 is provided in the central portion of the downstream space 42, there is a distance from the upper surface of the film seal 31, and there is a possibility that the developer that has dropped on the upper surface of the film seal 31 cannot be sucked. On the other hand, in the first embodiment, the lower vent 46 is disposed in the lower part of the downstream space 42 and can efficiently suck the developer received on the upper surface of the film seal 31.

FIG. 7 is an explanatory diagram of the gas flow when the upper vent is not provided in the developing device of the first embodiment.
In FIG. 7, if the upper vent 47 is not provided in the first embodiment, intake of the downstream space 42 is performed only by the lower vent 46 disposed at the lower portion of the downstream space 42. Therefore, as shown in FIG. 7, a vortex 51 is formed in the upper part of the downstream space 42. The vortex 51 is smaller than the vortex 07 in the conventional configuration shown in FIG. Therefore, it is also confirmed that the lower vent 46 alone can suppress the adverse effects caused by the vortex 07 as compared with the conventional configuration. In addition, as shown in FIG. 7, two small vortices 51 are generated in the upper portion of the downstream space 42 at a position relatively close to the photosensitive drum Py, and are wound around the vortex 51 in the form of the photosensitive member. The developer on the surface of the drum Py may be peeled off. Therefore, as in the first embodiment, it is desirable to provide the upper vent 47 to suppress the generation of the vortex 51.

  In the first embodiment, (width L3 of the upper vent 47) <(width L2 of the lower vent 46), particularly (open area of the upper vent 47) <(open area of the lower vent 46). Thus, the suction of the gas in the downstream space 42 is dominant in the suction from the lower vent 46. Therefore, the lowering of the suction efficiency of the lower vent 46 is suppressed. In particular, in the first embodiment, (opening area of the main intake port 32)> (opening area of the lower ventilation port 46) + (opening area of the upper ventilation port 47) is set. It is hard to be damaged, and the intake capacity of the lower vent 46 is not easily damaged even in the downstream space 42.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is made in the range of the summary of this invention described in the claim. Is possible. Modification examples (H01) to (H06) of the present invention are exemplified below.
(H01) In the above-described embodiment, the copying machine U as an example of the image forming apparatus is illustrated. However, the present invention is not limited to this, and can be applied to a printer, a FAX, or a multifunction machine having a plurality of these functions.

(H02) In the above embodiment, it is desirable to provide the upper vent 47. However, even if only the lower vent 46 is provided, an improvement effect is seen as shown in FIGS. A configuration is also possible. At this time, it is desirable to form the lower vent 46 at the lower part of the downstream space 42, but it is also possible to provide it at the central part 11 or the upper part in the vertical direction.
(H03) In the above-described embodiment, the relationship between the widths L1 to L3 of the openings 32, 46, and 47 and the relationship between the opening areas are preferably illustrated relationships, but are not limited thereto. It can be arbitrarily changed according to the suction capacity, design, specifications, etc. to be secured.

(H04) In the above embodiment, the configuration in which the fan 26 sucks from the rear end of the developing device Gy is exemplified, but the present invention is not limited to this. It is also possible to adopt a configuration in which suction is performed from the front end, or a configuration in which suction is performed by guiding to the center portion in the front-rear direction and connecting to a pipe as in Patent Documents 1 and 3. When suction is performed from the front end, the lower vent 46 and the upper vent 47 are preferably arranged at the rear end. In the configuration of guiding to the center, the vents 46 and 47 are provided at both front and rear ends. It is desirable. In the configuration of the first embodiment, the vent holes 46 and 47 are preferably provided only on the front end side, but it is also possible to provide vent holes on the rear end side.

(H05) In the above-described embodiment, the configuration in which the main intake port 32 is partitioned by the partition wall 36 is illustrated, but the present invention is not limited to this, and a configuration in which the partition wall 36 is not provided is also possible.
(H06) In the above-described embodiment, the vent is illustrated as a single unit on the rear end side of the developing device, but the present invention is not limited to this. It is also possible to arrange a plurality of vents according to the numerical aperture, the opening air volume, and the position of the cloud generation source in the axial direction.

26 ... suction device,
31 ... flow path,
32 ... 1st opening,
41 ... Leakage prevention member,
42 ... a space between the leakage preventing member and the first opening,
46 ... second opening,
47. Third opening,
F: Fixing device,
Gy, Gm, Gc, Gk ... developing device,
L1: the distance between the end partition on the other end of the first opening and the end wall;
L2: the axial length of the second opening,
L3: the axial length of the third opening,
Py, Pm, Pc, Pk ... image carrier,
R0y, R0m, R0c, R0k, a developer holder,
ROSy, ROSm, ROSc, ROSk ... latent image forming device,
S ... medium,
T1 + B + T2 + CLB ... transfer device,
U: Image forming apparatus.

Claims (3)

A developer holding body disposed on the surface, facing the image holding body, and rotated while holding the developer;
A first opening disposed downstream of the developer holder relative to the rotation direction of the image carrier and capable of sucking the floating developer;
A flow path connected to the first opening;
A suction device connected to the flow path for sucking a gas;
A leakage preventing member disposed downstream of the first opening with respect to the rotation direction of the image carrier, and preventing leakage of the developer;
A second opening disposed in a space between the leakage preventing member and the first opening and connecting the flow path;
The second opening disposed downstream of the first opening and upstream of the leakage preventing member with respect to the rotation direction of the image carrier;
A third opening disposed upstream of the second opening and downstream of the first opening with respect to the rotation direction of the image carrier;
The first opening partitioned at a predetermined interval with respect to the axial direction of the developer holder;
With
With respect to the axial direction of the developer holder, the distance between the end partition on the other end side of the first opening and the end wall is L1, and the axial length of the second opening is L2. The developing device is characterized in that L1>L2> L3 when the length of the third opening in the axial direction is L3 . The flow path extending along the axial direction of the developer holder;
The suction device connected to one end of the flow path in the axial direction and sucking gas;
In the space between the leakage prevention member and the first opening, the second opening disposed corresponding to the other end side of the flow path;
The developing device according to claim 1, further comprising: An image carrier,
A latent image forming apparatus for forming a latent image on the surface of the image carrier;
The developing device according to claim 1 or 2 , wherein a latent image on the surface of the image carrier is developed into a visible image;
A transfer device for transferring a visible image of the surface of the image carrier to a medium;
A fixing device for fixing a visible image on the surface of the medium;
An image forming apparatus comprising:

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