Developing device and image forming apparatus

Abstract

To achieve both exhaust of air inside a developing device and suction of scattered toner, while avoiding an increase in the size of the developing device, compared to a case where an exhaust passage and a suction passage are all arranged at the same position along an axial direction of developer holding means.SOLUTION: A developing device comprises: a housing that stores developer; developer holding means that is arranged in an opening of the housing facing an image carrier, and rotates while holding the developer; an exhaust passage that exhausts air inside the housing to the outside; and a suction passage that sucks in the developer leaking from the opening of the housing to the outside. The exhaust passage and the suction passage are arranged at different positions along an axial direction of the developer holding means.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a developing device and an image forming apparatus. [Background technology]

[0002] Conventionally, techniques relating to developing devices have already been proposed, for example, as disclosed in Patent Documents 1 to 3.

[0003] Patent Document 1 discloses a developer storage container that stores developer, a developer holder that is arranged at the opening of the developer storage container to rotate opposite to an image holder and holds the developer, an exhaust passage that exhausts air from within the developer storage container to the outside, a capturing member that captures toner in the exhaust air that passes through the exhaust passage, and a blocking member whose base end is held by the developer storage container and whose tip end is sandwiched between the developer storage container and the developer held in the developer holder on the downstream side of the opening in the direction of rotation of the developer holder to block the gap.

[0004] Patent Document 2 discloses a configuration in which an air vent is formed along the bottom wall of a developing tank that contains a developer carrier, and a suction means is provided to suck air from a duct formed in the air vent through a toner filter.

[0005] Patent Document 3 discloses a configuration including a duct provided above a developing device and communicating with an air outlet passage, exhaust means for generating an air flow within the duct, and a filter disposed on the air flow exhaust side of the duct for collecting toner that has passed through the duct together with the air in the developing container. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-049118 A [Patent Document 2] Japanese Patent Application Publication No. 08-220882 [Patent Document 3] JP 2013-125148 A Summary of the Invention [Problem to be solved by the invention]

[0007] The object of this invention is to achieve both the exhaust of air from within the developing device and the suction of scattered toner while avoiding an increase in size of the developing device, compared to when the exhaust passage and the suction passage are all located at the same position along the axial direction of the developer holding means. [Means for solving the problem]

[0008] The invention described in claim 1 comprises a housing for accommodating a developer, a developer holding means that is disposed in an opening of the housing facing the image carrier and that holds the developer and rotates; an exhaust passage for discharging air within the housing to the outside; a suction passage for suctioning the developer leaking to the outside through an opening of the housing; Equipped with In the developing device, the exhaust passage and the suction passage are disposed at different positions along the axial direction of the developer holding means.

[0009] The invention recited in claim 2 is the developing device according to claim 1, wherein the suction passage is disposed downstream in the direction of rotation of the developer holding means with respect to the opening of the housing.

[0010] The invention recited in claim 3 is the developing device according to claim 1, wherein the exhaust passage is disposed in an upper portion along the vertical direction of the housing.

[0011] The invention described in claim 4 is a developing device described in claim 3, wherein the exhaust passage is located downstream in the rotational direction of the developer holding means at the opening of the housing and at the same position as the suction passage when viewed in the direction of the rotational axis of the developer holding means.

[0012] The invention described in claim 5 is the developing device according to claim 1, wherein the suction passages are disposed at least at both ends in the axial direction of the developer holding means.

[0013] The invention described in claim 6 is the developing device described in claim 5, in which a further suction passage is disposed between the suction passages disposed at both axial ends of the developer holding means.

[0014] The invention described in claim 7 is the developing device described in claim 6, wherein the suction passages are disposed at N equal intervals (N is an integer of 2 or more) along the axial direction of the developer holding means.

[0015] An eighth aspect of the present invention is the developing device according to the fifth aspect, wherein the exhaust passage is disposed at a position other than the suction passage along the axial direction of the developer holding means.

[0016] The invention recited in claim 9 is the developing device according to claim 1, wherein the exhaust passage is provided at an outlet thereof with trapping means for trapping the developer leaking from the exhaust passage to the outside.

[0017] The invention described in claim 10 is the developing device described in claim 9, wherein the trapping means is provided in all of the exhaust passages.

[0018] An eleventh aspect of the present invention is the developing device according to the ninth aspect, wherein the trapping means is provided in a location other than the exhaust passage adjacent to the suction passage.

[0019] The invention described in claim 12 is a developing device described in claim 1, wherein a portion of the exhaust passage along the axial direction of the developer holding means is blocked, and the blocked exhaust passage is connected to the suction passage.

[0020] In the invention described in claim 13, the suction passages are provided at a plurality of locations including both ends and a center portion along an axial direction of the developer holding means, 13. The developing device according to claim 12, wherein the exhaust passage is closed at a position adjacent to the suction passage except for both ends and a central portion of the suction passage in the axial direction of the developer holding means.

[0021] The invention described in claim 14 comprises an image holding means for holding an electrostatic latent image, a developing means for developing the electrostatic latent image on the image holding means; Equipped with The image forming apparatus uses the developing device according to any one of claims 1 to 13 as the developing means. Effect of the Invention

[0022] According to the invention described in claim 1, compared to a case in which the exhaust passage and the suction passage are arranged at the same position along the axial direction of the developer holding means, it is possible to avoid increasing the size of the developing device while simultaneously exhausting air from within the developing device and suctioning scattered toner.

[0023] According to the invention described in claim 2, the suction passage can effectively suck in developer discharged with the rotation of the developer holding means, compared to when the suction passage is positioned upstream of the opening of the housing in the direction of rotation of the developer holding means.

[0024] According to the invention described in claim 3, the exhaust passage can exhaust air inside the housing to the outside without interfering with the developer inside the housing, compared to when the exhaust passage is located at the bottom along the vertical direction of the housing.

[0025] According to the invention as set forth in claim 4, the exhaust passage is positioned at a different position from the suction passage along the rotation direction of the developer holding means, so that the developing device can be prevented from becoming large in size, compared to a case in which the exhaust passage is positioned at a different position from the suction passage along the rotation direction of the developer holding means.

[0026] According to the invention described in claim 5, the suction passage can effectively suck in developer leaking to the outside from the opening, compared to when the suction passage is not positioned at both ends along the axial direction of the developer holding means.

[0027] According to the invention described in claim 6, it becomes easier to suck up developer leaking from a middle position along the axial direction of the developer holding means, compared to when suction passages are arranged only at both ends along the axial direction of the developer holding means.

[0028] According to the invention described in claim 7, the suction passage can evenly suck in developer leaking to the outside from the opening, compared to when the suction passage is arranged unevenly along the axial direction of the developer holding means.

[0029] According to the invention described in claim 8, the exhaust passage can be prevented from becoming large in size as compared to a case in which the exhaust passage overlaps partially or entirely with the suction passage along the axial direction of the developer holding means.

[0030] According to the invention described in claim 9, the exhaust passage can suppress leakage of developer from the exhaust passage compared to a case in which the exhaust passage does not have a capturing means at its outlet portion for capturing developer leaking to the outside from the exhaust passage.

[0031] According to the invention as recited in claim 10, the capturing means can reduce the amount of developer leaking from the exhaust passage, compared to a case in which the capturing means is provided in a part of the exhaust passage.

[0032] According to the invention described in claim 11, the trapping means can suppress a decrease in the exhaust effect caused by clogging of the trapping means with developer, compared to a case in which the trapping means is provided in every exhaust passage.

[0033] According to the invention described in claim 12, the exhaust effect of the exhaust passage can be maintained as compared with the case where the exhaust passage is simply blocked.

[0034] According to the invention described in claim 13, it is possible to more effectively exhaust air from within the developing device and to suction the scattered toner, compared to a case in which the exhaust passage is blocked regardless of the position of the suction passage.

[0035] According to the invention described in claim 14, it is possible to achieve both the discharge of air from within the developing device and the suction of scattered toner, compared to a case in which a developing device described in any of claims 1 to 13 is not used as the developing means. [Brief description of the drawings]

[0036] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus to which a developing device according to a first embodiment of the present invention is applied; [Diagram 2] 1 is a configuration diagram showing an image forming section of an image forming apparatus to which a developing device according to a first embodiment of the present invention is applied. [Diagram 3] 1 is a vertical cross-sectional view showing a developing device according to a first embodiment of the present invention; [Figure 4] 1 is a rear configuration view showing a developing device according to a first embodiment of the present invention; [Diagram 5] 1 is a vertical cross-sectional view showing a developing device according to a first embodiment of the present invention; [Figure 6] 1 is a rear view of a developing device according to a first embodiment of the present invention, showing a state in which a passage forming member is removed; [Figure 7] 1 is a perspective configuration diagram showing a main part of a developing device according to a first embodiment of the present invention; [Figure 8] FIG. 2 is a perspective view showing the arrangement of a developing device and a suction duct; [Figure 9] 4 is an explanatory diagram showing the operation of the developing device according to the first embodiment of the present invention; FIG. [Figure 10] 4 is an explanatory diagram showing the operation of the developing device according to the first embodiment of the present invention; FIG. [Figure 11] 11 is a perspective configuration view showing a main part of a developing device according to a second embodiment of the present invention; FIG. [Figure 12] FIG. 11 is a perspective configuration view showing a main portion of a developing device according to a third embodiment of the present invention. [Figure 13] 13 is a rear view of a developing device according to a fourth embodiment of the present invention with a passage forming member removed. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0038] [Embodiment 1] Figures 1 and 2 show an image forming apparatus to which a developing device according to embodiment 1 is applied. Figure 1 shows an overview of the entire image forming apparatus, and Figure 2 shows an enlarged view of the main parts (imaging device, etc.) of the image forming apparatus. In Figure 1, the symbol X indicates the horizontal direction (width direction) of the image forming apparatus, the symbol Y indicates the depth direction of the image forming apparatus, and the symbol Z indicates the vertical direction of the image forming apparatus.

[0039] <Overall configuration of image forming apparatus> The image forming apparatus 1 according to the first embodiment is configured as, for example, a color printer. As shown in Fig. 1, the image forming apparatus 1 includes, inside an apparatus main body 1a, a plurality of image forming devices 10 that form toner images developed with toner constituting a developer 4, an intermediate transfer device 20 that holds the toner images formed by the image forming devices 10 and transports them to a secondary transfer position where they are finally secondarily transferred onto a recording paper 5 as an example of a recording medium, a paper feed device 50 that stores and transports the required recording paper 5 to be supplied to the secondary transfer position of the intermediate transfer device 20, and a fixing device 40 that fixes the toner image on the recording paper 5 secondarily transferred by the intermediate transfer device 20. The apparatus main body 1a of the image forming apparatus 1 is formed of a support structure member, an exterior cover, and the like.

[0040] The imaging device 10 is composed of four imaging devices 10Y, 10M, 10C, and 10K that are dedicated to forming toner images of four colors, yellow (Y), magenta (M), cyan (C), and black (K), respectively. These four imaging devices 10 (Y, M, C, and K) are arranged in a line in an inclined state in the internal space of the device main body 1a. Of the four imaging devices 10 (Y, M, C, and K), the yellow (Y) imaging device 10Y is located relatively high above along the vertical direction Z, and the black (K) imaging device 10K is located relatively low.

[0041] As shown in Figures 1 and 2, each of the yellow (Y), magenta (M), cyan (C) and black (K) image creating devices 10 (Y, M, C, K) is equipped with a rotating photosensitive drum 11 as an example of an image holding means for holding an electrostatic latent image, and around this photosensitive drum 11, various devices as examples of toner image forming means, such as those described below, are mainly arranged. The main devices are a charging device 12 which charges the peripheral surface (image bearing surface) of the photosensitive drum 11 capable of forming an image to a required potential, an exposure device 13 which irradiates the charged peripheral surface of the photosensitive drum 11 with light based on image information (signal) to form an electrostatic latent image for each color with a potential difference, a developing device 14 as an example of a developing means which develops the electrostatic latent image with toner of the developer 4 of the corresponding color (Y, M, C, K) to form a toner image, a primary transfer device 15 which transfers each toner image to the intermediate transfer device 20, and a drum cleaning device 16 which removes and cleans any toner and other deposits remaining on and adhering to the image bearing surface of the photosensitive drum 11 after the primary transfer.

[0042] The photoconductor drum 11 has an image bearing surface formed on the peripheral surface of a grounded cylindrical or columnar substrate, the peripheral surface of which has a photoconductive layer (photosensitive layer) made of a photosensitive material. The photoconductor drum 11 is supported so as to rotate in the direction indicated by the arrow A by power transmitted from a drive device (not shown).

[0043] As shown in Fig. 2, the charging device 12 includes a contact-type charging roll 121 that is disposed in contact with the photoconductor drum 11. A cleaning roll 122 that cleans the surface of the charging roll 121 is disposed on the rear side of the charging roll 121. A charging voltage is supplied to the charging roll 121 of the charging device 12. When the developing device 14 performs reversal development, the charging voltage is a voltage or current of the same polarity as the charging polarity of the toner supplied from the developing device 14. Note that the charging device 12 may be a non-contact charging device such as a scorotron that is disposed in a non-contact state with the surface of the photoconductor drum 11.

[0044] The exposure device 13 forms an electrostatic latent image by irradiating the charged peripheral surface of the photoconductor drum 11 with light configured according to image information input to the image forming apparatus 1. When it is time to form a latent image, image information (signals) input to the image forming apparatus 1 by any means is transmitted to the exposure device 13.

[0045] The exposure device 13 is an LED print head that forms an electrostatic latent image by irradiating the photoconductor drum 11 with light corresponding to image information using LEDs (Light Emitting Diodes) as a plurality of light emitting elements arranged along the axial direction of the photoconductor drum 11. Note that the exposure device 13 may be one that deflects and scans laser light configured according to the image information along the axial direction of the photoconductor drum 11.

[0046] Each of the developing devices 14 is configured by arranging a developing roll 141 that holds the developer 4 and transports it to a development area facing the photosensitive drum 11, an agitation supply member 142 made of a screw auger or the like that supplies the developer 4 while stirring it so that it passes through the developing roll 141, an agitation transport member 143 made of a screw auger or the like that transports the developer 4 to the agitation supply member 142 while stirring it, and a layer thickness regulating member 144 that regulates the amount (layer thickness) of the developer held on the developing roll 141, inside a device housing 140 as an example of a casing in which an opening portion at a position facing the photosensitive drum 11 and a developer storage chamber are formed. A developing voltage is supplied to the developing device 14 between the developing roll 141 and the photosensitive drum 11 from a power supply device (not shown). For example, a two-component developer containing a non-magnetic toner and a carrier is used as the developer 4 of each color. The configuration of the developing device 14 will be described in detail later.

[0047] The primary transfer device 15 is a contact type transfer device that includes a primary transfer roll that rotates in contact with the periphery of the photosensitive drum 11 via the intermediate transfer belt 21 and is supplied with a primary transfer voltage. As the primary transfer voltage, a DC voltage showing a polarity opposite to the charge polarity of the toner is supplied from a power supply device (not shown).

[0048] 2, the drum cleaning device 16 is composed of a container-shaped main body 16a with a portion open, a cleaning plate 16b that is arranged to come into contact with the peripheral surface of the photosensitive drum 11 after primary transfer with a required pressure to remove and clean residual toner and other deposits, and a sending member 16c such as a screw auger that collects the toner and other deposits removed by the cleaning plate 16b and conveys them to a collection system (not shown). A plate-shaped member (e.g., a blade) made of a material such as rubber is used as the cleaning plate 16b.

[0049] As shown in Fig. 1, the intermediate transfer device 20 is disposed so as to be located above each of the image forming devices 10 (Y, M, C, K) in the vertical direction Z. As shown in Fig. 2, the intermediate transfer device 20 is mainly composed of an intermediate transfer belt 21 that rotates in the direction indicated by the arrow B while passing through a primary transfer position between the photosensitive drum 11 and the primary transfer device 15, a plurality of belt support rolls 22-25 that support the intermediate transfer belt 21 in a desired state from its inner surface and rotatably, a secondary transfer device 30 that is disposed on the outer peripheral surface (image bearing surface) side of the intermediate transfer belt 21 supported by the belt support roll 25 and performs a secondary transfer of the toner image on the intermediate transfer belt 21 to the recording paper 5, and a belt cleaning device 26 that removes and cleans the toner, paper powder, and other deposits that remain and adhere to the outer peripheral surface of the intermediate transfer belt 21 after passing through the secondary transfer device 30.

[0050] In this embodiment 1, as described above, the intermediate transfer device 20 is disposed so as to be located above each of the imaging devices 10 (Y, M, C, K) in the vertical direction Z. Therefore, since the developing device 14 disposed on the outer periphery of the photosensitive drum 11 transfers the toner image developed on the photosensitive drum to the intermediate transfer belt 21 of the intermediate transfer device 20 located above in the vertical direction Z as shown in FIG. 2, it is difficult to form a gap between the upper part of the developing device 14 and the intermediate transfer belt 21, and the upper end of the developing device 14 is inevitably disposed in a position close to the intermediate transfer belt 21.

[0051] An endless belt made of a material in which a resistance adjusting agent such as carbon black is dispersed in a synthetic resin such as polyimide resin or polyamide resin is used as the intermediate transfer belt 21. The belt support roll 22 is configured as a drive roll that is rotated by a drive unit (not shown) and as a support roll for a belt cleaning unit 26, the belt support roll 23 is configured as a surface finishing roll that maintains the running position of the intermediate transfer belt 21, the belt support roll 24 is configured as a tension applying roll that applies tension to the intermediate transfer belt 21, and the belt support roll 25 is configured as a backup roll for secondary transfer.

[0052] 1, the secondary transfer device 30 is a contact type transfer device including a secondary transfer roll 31 that rotates in contact with the circumferential surface of the intermediate transfer belt 21 and is supplied with a secondary transfer voltage at a secondary transfer position, which is the outer circumferential surface portion of the intermediate transfer belt 21 supported by the belt support roll 25 in the intermediate transfer device 20. A DC voltage having the same polarity as or opposite to the charge polarity of the toner is supplied as the secondary transfer voltage to the secondary transfer roll 31 or the belt support roll 25 of the intermediate transfer device 20.

[0053] The belt cleaning device 26 is composed of a container-shaped main body 260 with a portion open, a cleaning plate 261 that is arranged so as to come into contact with the peripheral surface of the intermediate transfer belt 21 after secondary transfer with a required pressure and removes and cleans any adhering matter such as residual toner, and a sending member 262 such as a screw auger that collects the adhering matter such as toner removed by the cleaning plate 261 and conveys it to a collection system (not shown). A plate-shaped member (for example, a blade) made of a material such as rubber is used as the cleaning plate 261.

[0054] 1, the fixing device 40 is configured by arranging a heating rotor 41 in the form of a roll or belt, which is heated by a heating means so that the surface temperature is maintained at a required temperature, and a pressure rotor 42 in the form of a roll or belt, which rotates in contact with the heating rotor 41 at a specified pressure in a state substantially along the axial direction of the heating rotor 41. In this fixing device 40, the contact portion where the heating rotor 41 and the pressure rotor 42 come into contact with each other becomes a fixing processing portion where the required fixing process (heating and pressurization) is performed. At the exit portion of the fixing device 40, an exit roll 43 is arranged to transport the recording paper 5 that has been subjected to the fixing process in the fixing device 40.

[0055] The paper feeder 50 is disposed so as to be located below the imaging devices 10 (Y, M, C, K) for yellow (Y), magenta (M), cyan (C), and black (K). This paper feeder 50 is mainly composed of one (or more) paper containers 51 that contain stacks of recording paper 5 of desired sizes, types, etc., and feeders 52, 53 that feed the recording paper 5 one sheet at a time from the paper container 51. The paper container 51 is attached so as to be able to be pulled out, for example, from the front side (the side that the user faces during operation) of the device main body 1a, or in the illustrated example, from the right side along the width direction X.

[0056] Examples of the recording paper 5 include plain paper, thin paper, and OHP sheets used in electrophotographic copiers, printers, etc. In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper 5 is as smooth as possible, and for example, coated paper in which the surface of plain paper is coated with a resin or the like, or so-called thick paper with a relatively large basis weight such as art paper for printing can be used.

[0057] 1, a paper feed conveying path 55 is provided between the paper feeder 50 and the secondary transfer device 30, the paper feeder conveying path 55 being configured with a single (or multiple) paper conveying roll pair 54 that conveys the recording paper 5 sent out from the paper feeder 50 to the secondary transfer position, a conveying guide (not shown), and the like. The paper conveying roll pair 54 disposed immediately before the secondary transfer device 30 is configured as, for example, a registration roll that adjusts the conveying timing of the recording paper 5. In addition, a paper discharge conveying path 58 is provided at the upper part of the fixing device 40 along the vertical direction Z, the paper discharge conveying path 58 being equipped with a paper discharge roll pair 57 that discharges the fixed recording paper 5 sent out from the exit roll 43 of the fixing device 40 to a discharge tray 56 provided at the upper part of the device main body 1a.

[0058] Inside the device main body 1a, there is provided a double-sided conveying path 60 equipped with multiple double-sided conveying roll pairs 59 that reverse the recording paper 5 and convey it again to the paper conveying roll pair 54 by switching the rotation direction of the paper discharge roll pair 57 from the forward direction (discharge direction) to the reverse direction while the rear end of the recording paper 5 with an image formed on one side is held by the paper discharge roll pair 57.

[0059] In Figure 1, symbol 61 indicates a manual feed tray that is openably and closably provided on the side (left side in the figure) of the device body 1a of the image forming device 1, and between the manual feed tray 61 and the pair of paper transport rolls 54, there is provided a feed device 62 that feeds out the recording paper 5 stored in the manual feed tray 61 one sheet at a time, and a manual feed paper transport path 64 that is composed of a pair of paper transport rolls 63 and a transport guide (not shown), etc.

[0060] In addition, the reference numerals 145 (Y, M, C, K) in FIG. 1 each indicate a toner cartridge arranged in a direction perpendicular to the paper surface, each cartridge containing developer including at least toner to be supplied to the corresponding developing device 14 (Y, M, C, K).

[0061] 1 indicates a control device that comprehensively controls the operation of the image forming apparatus 1. The control device 100 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), or a bus for connecting the CPU, the ROM, etc., a communication interface, etc. (not shown).

[0062] <Operation of image forming device> Hereinafter, a basic image forming operation by the image forming apparatus 1 will be described.

[0063] Here, an operation of forming a full-color image by combining toner images of four colors (Y, M, C, K) using the four image forming devices 10 (Y, M, C, K) will be described.

[0064] When the control device 100 of the image forming apparatus 1 receives command information requesting an image forming operation (printing), the four image forming devices 10 (Y, M, C, K), the intermediate transfer device 20, the secondary transfer device 30, the fixing device 40, etc. start up.

[0065] In each imaging device 10 (Y, M, C, K), first, each photoconductor drum 11 rotates in the direction indicated by arrow A, and each charging device 12 charges the surface of each photoconductor drum 11 to a required polarity (negative polarity in the first embodiment) and potential. Next, exposure device 13 irradiates the surface of the charged photoconductor drum 11 with light emitted based on an image signal obtained by converting image information input to image forming device 1 into each color component (Y, M, C, K), and forms an electrostatic latent image of each color component composed of a required potential difference on the surface.

[0066] Next, each image forming device 10 (Y, M, C, K) develops the electrostatic latent image of each color component formed on the photoconductor drum 11 by supplying toner of the corresponding color (Y, M, C, K) charged to the required polarity (negative polarity) from the developing roll 141 and electrostatically attaching it to the electrostatic latent image of each color component. Through this development, the electrostatic latent image of each color component formed on each photoconductor drum 11 is visualized as a toner image of four colors (Y, M, C, K) developed with the toner of the corresponding color.

[0067] Next, when the toner images of each color formed on the photosensitive drum 11 of each image creating device 10 (Y, M, C, K) are transported to the primary transfer position, the primary transfer device 15 (Y, M, C, K) performs primary transfer of the toner images of each color in such a manner that they are superimposed in order onto the intermediate transfer belt 21 rotating in the direction indicated by arrow B of the intermediate transfer device 20.

[0068] In addition, in each of the imaging devices 10 (Y, M, C, K) where the primary transfer has been completed, the drum cleaning device 16 scrapes off any adhering matter to clean the surface of the photosensitive drum 11. This makes each of the imaging devices 10 (Y, M, C, K) ready for the next image formation operation.

[0069] Next, the intermediate transfer device 20 conveys the primary transferred toner image to the secondary transfer position by the rotation of the intermediate transfer belt 21. Meanwhile, the paper feeder 50 sends out the required recording paper 5 to the paper feed path 55 in accordance with the image creation operation. In the paper feed path 55, a pair of paper feed rolls 54 as registration rolls sends out and supplies the recording paper 5 to the secondary transfer position in accordance with the transfer timing.

[0070] At the secondary transfer position, the secondary transfer roll 31 of the secondary transfer device 30 performs secondary transfer of the toner images on the intermediate transfer belt 21 all at once onto the recording paper 5. In the intermediate transfer device 20 where the secondary transfer is completed, the belt cleaning device 26 removes and cleans the surface of the intermediate transfer belt 21 to remove any adhering matter such as toner remaining thereon after the secondary transfer.

[0071] Next, the recording paper 5 onto which the toner image has been secondarily transferred is peeled off from the intermediate transfer belt 21 and the secondary transfer roll 31, and then conveyed to the fixing device 40. In the fixing device 40, the recording paper 5 after the secondary transfer is introduced into and passes through a contact portion between the rotating heating rotator 41 and the pressure applying rotator 42, thereby performing the necessary fixing process (heating and pressurizing) to fix the unfixed toner image onto the recording paper 5. Finally, in the case of an image forming operation in which an image is only formed on one side of the recording paper 5 after fixing, the recording paper 5 after fixing is discharged by a paper discharge roll pair 57 to a discharge tray 56 installed at the top of the device main body 1a.

[0072] When forming images on both sides of the recording paper 5, the recording paper 5 with an image formed on one side is not discharged to the discharge tray 56 by the paper discharge roll pair 57, but the rotation direction of the paper discharge roll pair 57 is switched to the reverse direction while the paper discharge roll pair 57 is holding the rear end of the recording paper 5. The recording paper 5 transported in the reverse direction by the paper discharge roll pair 57 is transported to a double-sided transport path 60 equipped with a double-sided transport roll pair 59 and the like, and is transported again to the paper transport roll pair 54 in an inverted state. The paper transport roll pair 54 sends out and supplies the recording paper 5 to the secondary transfer position in accordance with the transfer timing, forms an image on the back side of the recording paper 5, and discharges the recording paper 5 with the image fixed on the back side to the discharge tray 56 installed at the top of the device main body 1a by the paper discharge roll pair 57.

[0073] By the above operation, a recording sheet 5 is outputted, on one or both sides of which a full-color image formed by combining four color toner images is formed.

[0074] <Configuration of the developing device> Figures 3 and 4 show a developing device according to embodiment 1 that is applied to an image forming apparatus configured as described above. Figure 3 is a vertical cross-sectional view showing the developing device together with a photosensitive drum and the like, and Figure 4 is a rear view showing the developing device as viewed from the opposite side to the photosensitive drum.

[0075] 3, the developing device 14 includes a device housing 140 as an example of a case. The device housing 140 is roughly divided into a lower housing 140a disposed at a lower portion of the developing device 14 in the vertical direction Z, and an upper housing 140b disposed at an upper portion of the developing device 14 in the vertical direction Z. The lower housing 140a and the upper housing 140b are joined airtight, and a developer storage chamber 150 that stores the two-component developer 4 is formed inside the device housing 140.

[0076] In the developing device 14 according to this embodiment 1, the upper housing 140b is not constructed as a single unit, but is constructed by dividing it into an upper housing main body 140b' that covers the entire upper part of the developing device 14, and a passage forming member 140b'' that covers the upper end surface of the upper housing main body 140b' to form exhaust passages 163, 163... and suction passages 167, 167... inside the upper housing main body 140b', as will be described later.

[0077] An opening 151 is provided in an area of ​​the device housing 140 facing the photosensitive drum 11. Inside the device housing 140, a developing roll 141 as an example of a developer holding means that holds and rotates the developer 4 is arranged rotatably along the direction of the arrow C so as to be partially exposed to the opening 151. The developing roll 141 has a magnet roll 141a as an example of a magnetic field generating means that is fixedly arranged inside and has a plurality of magnetic poles of a required polarity arranged at required positions along the circumferential direction, and a cylindrical developing sleeve 141b as an example of a developer transport means that is arranged on the outer periphery of the magnet roll 141a so as to be rotatable at a required rotation speed along the direction of the arrow C. The developing sleeve 141b is formed into a cylindrical shape from a non-magnetic material such as aluminum or non-magnetic stainless steel. The developing sleeve 141b is rotated by a driving force transmitted from the device main body 1a.

[0078] In the developing device 14 according to the first embodiment, the rotation direction C of the developing sleeve 141b is set to be opposite to the rotation direction A of the photosensitive drum 11. That is, the rotation direction A of the photosensitive drum 11 is set to be counterclockwise as shown in Fig. 3, whereas the rotation direction C of the developing sleeve 141b is set to be clockwise. As a result, the outer peripheral surface of the developing sleeve 141b moves in the same direction as the movement direction of the surface of the photosensitive drum 11 in the development region facing the photosensitive drum 11.

[0079] The rotation speed of the developing sleeve 141b is determined according to the productivity of the image forming apparatus 1, which is determined by the rotation speed (process speed) of the photoconductor drum 11. The productivity of the image forming apparatus 1 is represented, for example, by the number of A4 size (LEF) recording papers 5 on which images can be formed per unit time. The rotation speed (circumferential speed) of the developing sleeve 141b becomes faster as the productivity of the image forming apparatus 1 increases.

[0080] Inside the device housing 140, an agitation supply member 142 consisting of a screw auger (supply auger) or the like that scoops up the developer 4 contained in the developer storage chamber 150 and supplies it to the developing roll 141 is disposed obliquely below the developing roll 141 in the vertical direction. The agitation supply member 142 is rotationally driven in a required rotation direction by a rotational driving force transmitted from the developing roll 141. Also, inside the device housing 140, an agitation transport member 143 consisting of a screw auger (admix auger) or the like that transports the developer 4 supplied to the inside of the device housing 140 while stirring it is disposed obliquely below the agitation supply member 142. The agitation transport member 143 is rotationally driven in a required rotation direction by a driving force transmitted from the agitation supply member 142 or the like.

[0081] The lower housing 140a is provided with a first storage section 147 and a second storage section 148 formed in a substantially semi-cylindrical cross section to store the agitation supply member 142 and the agitation transport member 143. The first storage section 147 and the second storage section 148 are separated by a partition wall 152 provided in the lower housing 140a. Above the first storage section 147 is a space for a developer storage chamber 150. The upper housing main body 140b' is provided with a third storage section 153 formed to form a part of a substantially cylindrical cross section that forms a transport passage for the developer 4 together with the second storage section 148 of the lower housing 140a.

[0082] At both ends of the partition wall 152 in the longitudinal direction, first and second passages (not shown) are provided for transferring the developer 4 between the agitation supply member 142 and the agitation transport member 143. The end of the agitation transport member 143 on the inner side along the axial direction is extended so as to protrude from the rear side of the device housing 140, as shown in FIG. 4. At the extended portion of the agitation transport member 143, a substantially cylindrical supply section 154 with a closed end is provided. The substantially cylindrical supply section 154 has a supply port 155 through which the developer 4 of the corresponding color is supplied from the toner cartridge 145 (Y, M, C, K). The supply port 155 is covered by a shutter member (not shown) so as to be openable and closable.

[0083] In FIG. 4, reference numeral 156 denotes a coupling portion that transmits a rotational driving force to the developing roll 141 from the apparatus main body 1a side.

[0084] In the developing device 14 configured as described above, the rotation speed of the developing roll 141 tends to be increased in order to meet the improvement in productivity required for the image forming apparatus 1. When the rotation speed of the developing roll 141 in the developing device 14 is increased, as shown in FIG. 3, the amount of air taken into the device housing 140 from the opening 151 increases with the rotation of the developing roll 141, and the internal pressure of the device housing 140 increases. Note that, in the opening 151 of the developing device 14, the upstream end along the rotation direction of the developing roll 141 is blocked by a layer thickness regulating member 144 that regulates the layer thickness of the magnetic brush of the developer 4 held on the outer periphery of the developing sleeve 141b, and the magnetic brush of the developer 4.

[0085] If the internal pressure of the device housing 140 rises and no measures are taken, toner will scatter to the outside from the area facing the opening 151 of the developing roll 141, causing a so-called toner cloud, and there is a risk that the inside of the device main body 1a will be contaminated by the scattered toner.

[0086] Therefore, as disclosed in Patent Document 1, the applicant has already proposed a configuration including an exhaust passage for discharging air from within a developer storage container to the outside, a capturing member for capturing toner in the exhaust gas passing through the exhaust passage, and a blocking member whose base end is held in the developer storage container and whose tip end is sandwiched between the developer storage container and the developer held in the developer holder on the downstream side of the opening in the direction of rotation of the developer holder to block the gap.

[0087] However, in the case of the technology disclosed in Patent Document 1, it was found that over time, the filter (an example of a capturing member) becomes clogged with the collected toner, making it impossible to exhaust the air inside the developing device to the outside through the exhaust passage, and the internal pressure of the developer storage container gradually increases, causing toner to flow out as scattered toner from the area facing the opening of the developer holder. This creates a new technical problem.

[0088] One possible solution to this new technical problem is to provide a suction duct on the rear side of the developing device along the longitudinal direction thereof, for sucking in scattered toner leaking from the developing device.

[0089] However, when the suction duct is located on the rear side of the developing device, since the suction duct is away from the opening of the developing device, it is possible to suck up a certain amount of scattered toner in the vicinity of the suction duct along the longitudinal direction of the developing device, but it is not possible to effectively suck up scattered toner leaking from the front side away from the suction duct along the longitudinal direction of the developing device, and it was found that the housing of the developing device becomes soiled by scattered toner.

[0090] In addition, to address this new technical issue, in addition to the exhaust passage, it may be possible to provide a suction passage that captures the scattered toner flowing out from the opening of the developing device over the entire area along the axial direction of the developer holding means at the opening of the developing device, thereby sucking in the scattered toner that leaks out from the opening of the developing device to the outside.

[0091] Due to its function, the suction passage is disposed at the downstream end in the direction of rotation of the developer holding means at the opening of the developing device, that is, at the upper end in the vertical direction of the developing device.

[0092] However, as described above, the intermediate transfer belt 21 of the intermediate transfer device 20 is present above the developing device 14. Therefore, if an exhaust passage is provided in addition to an exhaust passage at the upper end of the developing device 14 along the vertical direction Z, the developing device 14 will become larger, which will in turn result in an increase in the size of the image forming apparatus 1, creating another technical problem.

[0093] Therefore, in order to avoid increasing the size of the developing device while simultaneously exhausting the air inside the developing device and sucking up scattered toner, the developing device of this embodiment 1 is provided with an exhaust passage that exhausts the air inside the casing to the outside and a suction passage that sucks up the developer that leaks to the outside from an opening in the casing, and the exhaust passage and the suction passage are arranged at different positions along the axial direction of the developer holding means.

[0094] That is, as shown in FIG. 5, the developing device 14 according to this embodiment 1 has a double structure in which an area located above the developing roll 141 and agitation supply member 142 of the device housing 140 in the vertical direction Z is partitioned by an upper housing main body 140b' and a passage forming member 140b", and a space 157 that is relatively low in height in the vertical direction Z and relatively long in the horizontal direction X toward the inside of the device housing 140 is formed between the upper housing main body 140b' and the passage forming member 140b". The space 157 is open on the side facing the photosensitive drum 11 over substantially the entire length along the axial direction of the developing roll 141.

[0095] In order to form a space 157, the upper housing main body 140b' of the developing device 14 includes a covering cylindrical portion 158 that forms a part of a cylindrical shape covering the outer peripheral surface of the developing roll 141 exposed to the outside at the end of the opening 151 downstream in the rotation direction C of the developing roll 141, a curved portion 159 that curves obliquely downward from the back side of the covering cylindrical portion 158 toward the upper part of the agitation supply member 142, and a bent portion 160 that bends further downward from the back side of the curved portion 159 in a substantially V-shape. A recess 161 that is joined to the partition wall 152 of the lower housing 140a is provided at the lower end of the bent portion 160. In addition, a side wall 162 on the back side of the bent portion 160 is extended to the upper end of the device housing 140. This back side side wall 162 is joined to the passage forming member 140b'' to form the space 157.

[0096] As shown in FIGS. 3 and 6, between the upper housing main body 140b' and the passage forming member 140b'', exhaust passages 163, 163... are formed by partitioning a part of the space 157 for discharging air inside the device housing 140 to the outside.

[0097] In order to suppress an increase in the internal pressure of the developing device 14, it is desirable that the exhaust passages 163, 163... exhaust the air inside to the outside over substantially the entire area along the axial direction of the developing roll 141 of the developing device 14. In addition, since it is necessary to exhaust to the outside the air present in the upper part along the vertical direction Z of the developer storage chamber 150 inside the device housing 140 of the developing device 14, the exhaust passages 163, 163... are disposed at the upper part along the vertical direction Z of the developing device 14, that is, at the downstream end along the rotation direction of the developing roll 141 at the opening 151 of the device housing 140, on the intermediate transfer belt 21 side, which is the same position as the suction passages 167, 167... described later.

[0098] In this way, by arranging the exhaust passages 163, 163... at the upper part of the device housing 140 in the vertical direction Z, it becomes possible to exhaust the air inside the device housing 140 to the outside without interfering with the developer 4 inside the device housing 140, compared to when the exhaust passages 163, 163... are arranged at the lower part of the device housing 140 in the vertical direction Z.

[0099] In addition, by arranging the exhaust passages 163, 163... at the same position along the rotation direction C of the developing roll 141 as the suction passages 167, 167..., it is possible to avoid the developing device 14 becoming larger in size compared to a case where the position along the rotation direction C of the developing roll 141 is different from that of the suction passages 167, 167....

[0100] A plurality of exhaust passages 163, 163... are arranged along the axial direction of the developing roll 141. As shown in Fig. 3, an outlet end 163a of each exhaust passage 163, 163... opens into a downstream end along the rotation direction C of the developing roll 141 in the opening 151 of the device housing 140. Also, an inlet end 163b of each exhaust passage 163, 163... opens into the curved portion 159 of the upper housing main body 140b'.

[0101] An inlet end 163b of each exhaust passage 163, 163... is surrounded by a partition wall 164 erected on the curved portion 159 of the upper housing main body 140b' so as to intersect with the longitudinal direction of the exhaust passage 163, 163.... The partition wall 164 has an opening close to the inner surface of the passage forming member 140b", and constitutes the inlet end 163b of each exhaust passage 163, 163.... The partition wall 164 prevents toner in the developer accommodating chamber 150 from flowing out.

[0102] A side wall 165 on the rear side of the partition wall 164 extends to the upper end of the device housing 140. The side wall 165 of the partition wall 164 is joined to the passage forming member 140b" to partition the exhaust passages 163, 163.... Adjacent exhaust passages 163, 163... are separated from each other by partition walls 166, as shown in FIG. 6.

[0103] 3 and 6, suction passages 167, 167... are formed between the upper housing main body 140b' and the passage forming member 140b" by partitioning part of the space 157. The suction passages 167, 167... are arranged such that their positions along the axial direction of the developing roll 141 are all different from the exhaust passages 163, 163....

[0104] In this way, compared to a case in which the exhaust passages 163, 163... and the suction passages 167, 167... are partially positioned at different positions along the axial direction of the developing roll 141, it is possible to prevent the developing device 14 from becoming large.

[0105] The suction passages 167, 167... suck the scattered toner flowing out from the opening 151 of the developing device 14, and desirably suck the scattered toner flowing out over substantially the entire area along the axial direction of the developing roll 141 of the developing device 14. In addition, since the suction passages 167, 167... suck the scattered toner flowing out from the opening 151 of the developing device 14, they are disposed on the intermediate transfer belt 21 side, which is the downstream end in the rotation direction of the developing roll 141 at the opening 151 of the developing device 14, that is, the upper part of the developing device 14 in the vertical direction Z.

[0106] As shown in Fig. 5, an inlet end 167a of each of the suction passages 167, 167... is opened at a downstream end in the rotation direction of the developing roll 141 at the opening 151 of the device housing 140. That is, each of the suction passages 167, 167... is opened at a downstream end in the rotation direction of the developing roll 141 at the opening 151 of the device housing 140, i.e., at the same position as the exhaust passages 163, 163.... Also, as shown in Fig. 6, an outlet end 167a of each of the suction passages 167, 167... is disposed inside the device housing 140.

[0107] In this way, the suction passages 167, 167... are able to effectively suck in toner discharged from the opening 151 as the developing roll 141 rotates, compared to when the suction passages 167, 167... are opened upstream in the direction of rotation of the developing roll 141 at the opening 151 of the device housing 140.

[0108] The suction passages 167, 167... have their ends 167b on the inner side of the device housing 140 joined to a communication passage 168 arranged along the axial direction of the developing roll 141, so that the suction passages 167, 167... are in communication with each other.

[0109] 6 and 7, the exhaust passages 163, 163... are formed in the upper part of the upper housing body 140b', and as a result, the suction passages 167, 167... are partitioned from the exhaust passages 163, 163... as the remaining passages of the space 157. In other words, the remaining passage areas of the space 157 that are not partitioned by the exhaust passages 163, 163... are the suction passages 167, 167....

[0110] As shown in Fig. 3, the communication passage 168 is configured as a passage-like space located at the rear end of the curved portion 159 of the upper housing main body 140b' and above the bent portion 160 in the space 157. The communication passage 168 extends to the rear end of the developing device 14, and is connected to a suction fan (not shown) as an example of a suction means via a suction duct 169 as shown in Fig. 8. A filter for removing toner is provided at the exhaust port of the suction fan.

[0111] As described above, in the developing device 14 according to the first embodiment, the exhaust passages 163, 163... and the suction passages 167, 167... are all disposed at different positions along the axial direction of the developing roll 141. In other words, the exhaust passages 163, 163... and the suction passages 167, 167... are not provided at the same positions along the axial direction of the developing roll 141.

[0112] 6 and 7, the suction passages 167, 167... are disposed at both ends in the axial direction of the developing roll 141 and at N equal intervals (here, N is 4) between both ends. Among the suction passages 167, 167..., the interval between the suction passage 167 located at the front end in the axial direction of the developing roll 141 and the adjacent suction passage 167 is set to be slightly smaller than the intervals between the other suction passages 167.

[0113] In this way, by arranging the suction passages 167, 167... at both ends along the axial direction of the developing roll 141, toner leaking from both ends of the opening 151 can be effectively sucked in compared to a case where the suction passages 167, 167... are not arranged at both ends along the axial direction of the developing roll 141.

[0114] In addition, by arranging the suction passages 167, 167... at positions that divide the area between both ends along the axial direction of the developing roll 141 into N equal parts, it becomes easier to suck in toner that leaks from intermediate positions along the axial direction of the developing roll 141 compared to when the suction passages are arranged only at both ends.

[0115] Furthermore, by arranging the suction passages 167, 167... evenly along the axial direction of the developing roll 141, it is possible to evenly suck in toner leaking to the outside from the opening 151 while limiting the number of suction passages 167, 167..., compared to when they are arranged unevenly between both ends of the developing roll 141 along the axial direction.

[0116] In the illustrated example, the opening width W1 of the suction passages 167, 167 located at both ends in the axial direction of the developing roll 141 is set to be larger than the opening width W2 of the other suction passages 167, 167..., but the opening width W1 of the suction passages 167, 167 located at both ends may be set to be equal to or smaller than the opening width W2 of the other suction passages 167, 167.... When the opening width W1 of the suction passages 167, 167 located at both ends is set to be smaller than the opening width W2 of the other suction passages 167, 167..., it is desirable to increase the suction wind speed of the suction passages 167, 167 located at both ends.

[0117] On the other hand, in the developing device 14 of this embodiment 1, as shown in Figure 6, the exhaust passages 163, 163... are arranged at positions other than the suction passages 167, 167... along the axial direction of the developing roll 141, i.e., adjacent to the suction passages 167, 167... located at both ends along the axial direction of the developing roll 141 and the suction passages 167, 167... located in between.

[0118] 6, adjacent exhaust passages 163, 163... are separated from each other by partition walls 166, but adjacent exhaust passages 163, 163... may be formed as a continuous exhaust passage 163 without being separated from each other by partition walls 166. However, when adjacent exhaust passages 163, 163... are separated from each other by partition walls 166, the exhaust direction of the exhaust passages 163, 163... can be oriented in a direction intersecting the axial direction of the developing roll 141.

[0119] <Function of the developing device> In the above-described configuration, the developing device of embodiment 1 is capable of exhausting air from within the developing device and suctioning scattered toner while avoiding an increase in size of the developing device, as compared to a case in which the exhaust passages and suction passages are all positioned at the same position along the axial direction of the developer holding means, as follows.

[0120] That is, in an image forming apparatus 1 employing the developing device 14 according to this embodiment 1, as shown in Figures 1 and 2, in each image creating device 10 (Y, M, C, K), an electrostatic latent image is formed on the surface of the photosensitive drum 11, and the electrostatic latent image formed on the surface of the photosensitive drum 11 is developed by the corresponding developing device 14.

[0121] In the developing device 14, as shown in FIG. 3, the developing roll 141, the stirring supply member 142, and the stirring transport member 143 are rotationally driven in a required rotational direction, and the electrostatic latent image on the surface of the photosensitive drum 11 is visualized and developed with toner by a magnetic brush of the developer 4 held on the surface of the developing sleeve 141b of the developing roll 141.

[0122] As shown in FIG. 3, in the developing device 14, the developing roll 141 is driven to rotate at a required speed along the direction of the arrow C. As the developing roll 141 rotates, outside air is introduced into the device housing 140 through the opening 151, and the internal pressure tends to increase.

[0123] 9, the developing device 14 according to the first embodiment is provided with a plurality of exhaust passages 163, 163... along the axial direction of the developing roll 141, so that the air inside the device housing 140 is exhausted to the outside through each of the exhaust passages 163, 163.... Therefore, even in the developing device 14 in which the rotation speed of the developing roll 141 is increased to improve productivity, it is possible to suppress the internal pressure of the device housing 140 from increasing and scattering of toner to the outside of the developing device 14 from the opening 151.

[0124] 10, the developing device 14 according to the first embodiment is provided with a plurality of suction passages 167, 167... along the axial direction of the developing roll 141. Therefore, even if there is a risk that the toner leaks to the outside from the opening 151 or the exhaust passages 163, 163... of the device housing 140, the toner leaking to the outside from the opening 151 or the exhaust passages 163, 163... can be sucked in by the plurality of suction passages 167, 167.... Therefore, even in the developing device 14 in which the rotation speed of the developing roll 141 is increased to improve productivity, the toner can be prevented from floating inside the image forming device even if it leaks from the opening 151.

[0125] Furthermore, in the developing device 14 according to this embodiment 1, as shown in Figures 6 and 7, a plurality of exhaust passages 163, 163... and a plurality of suction passages 167, 167... are all arranged at different positions along the axial direction of the developing roll 141.

[0126] As a result, even if the developing device 14 has multiple exhaust passages 163, 163... and multiple suction passages 167, 167... arranged at the upper part of the device housing 140 along the vertical direction Z, which is the downstream end in the direction of rotation of the developing roll, at the opening 151 of the device housing 140, there is no need to arrange the exhaust passages 163, 163... and the suction passages 167, 167... at the same position along the axial direction of the developing roll 141, that is, in a so-called two-story structure at the upper part of the device housing 140 along the vertical direction Z, and this makes it possible to achieve both the exhaust of air from within the developing device 14 and the suction of scattered toner while avoiding an increase in the size of the developing device 14 and, by extension, the size of the image forming apparatus 1.

[0127] [Embodiment 2] Second Embodiment FIG. 11 is a structural view showing a developing device according to a second embodiment of the present invention.

[0128] 11, the developing device 14 according to the second embodiment is configured so that the end portions 163a on the outlet side of the exhaust passages 163, 163... are all blocked by filter members 170 as an example of a trapping means. The filter members 170 are provided at the end portions 163a on the outlet side of the exhaust passages 163, 163... by means of adhesion or the like.

[0129] In this way, in the case of the developing device 14 according to the above-mentioned embodiment 2, the toner discharged to the outside together with the air from the exhaust passages 163, 163... can be captured by the filter member 170, and the toner can be prevented from leaking to the outside from the exhaust passages 163, 163....

[0130] Furthermore, in the developing device 14 according to the above-mentioned second embodiment, even if the filter member 170 provided at the outlet of the exhaust passages 163, 163... becomes clogged with toner over time, the suction passages 167, 167... are provided along the axial direction of the developing roll 141 in the device housing 140, so that toner leaking to the outside from the opening 151 in the device housing 140 can be sucked in through the suction passages 167, 167..., and therefore it is possible to prevent or suppress the toner from leaking to the outside from the opening 151 over time.

[0131] The other configurations and operations are the same as those of the first embodiment, and therefore the description thereof will be omitted.

[0132] Third Embodiment Third Embodiment FIG. 12 is a structural view showing a developing device according to a third embodiment of the present invention.

[0133] The developing device 14 of this embodiment 3 is configured so that, rather than blocking all of the outlet side ends 163a of the exhaust passages 163, 163... by filter members 170 as an example of a capturing means, only some of the outlet side ends 163a of the exhaust passages 163, 163... are blocked by filter members 170 as an example of a capturing means.

[0134] That is, in the developing device 14 of this embodiment 3, as shown in FIG. 12, the outlet end 163a of one or more exhaust passages 163, 163... adjacent to the suction passages 167, 167... is left open, and the outlet end 163a of the exhaust passages 163, 163... not adjacent to the suction passages 167, 167... is blocked by a filter member 170.

[0135] In the developing device 14 according to the third embodiment, by blocking the outlet end 163a of the exhaust passages 163, 163... with a filter member 170, it becomes possible for the filter member 170 to capture toner leaking from the exhaust passages 163, 163... to the outside.

[0136] Moreover, even if the filter member 170 of the developing device 14 becomes clogged with toner over time, the air inside the device housing 140 can be reliably exhausted to the outside through the other exhaust passages 163, 163....

[0137] Furthermore, even if toner leaks from the exhaust passages 163, 163... in which the filter member 170 is not provided, the toner that has leaked to the outside can be sucked from the adjacent suction passages 167, 167....

[0138] The other configurations and operations are the same as those of the first embodiment, and therefore the description thereof will be omitted.

[0139] Fourth embodiment Fourth Embodiment FIG. 13 is a structural view showing a developing device according to a fourth embodiment of the present invention.

[0140] In the developing device of this embodiment 4, the suction passages are provided at multiple locations including both ends and the center along the axial direction of the developer holding means, and the exhaust passages are configured so that the exhaust passages adjacent to the suction passages located at positions excluding both ends and the center along the axial direction of the developer holding means of the suction passages are blocked.

[0141] In addition, in the developing device according to embodiment 4, a portion of the exhaust passage along the axial direction of the developer holding means is blocked, and the blocked exhaust passage is configured to communicate with the suction passage.

[0142] 13, the developing device 14 according to the fourth embodiment has suction passages 167, 167... that are open at both ends and the center in the axial direction of the developing roll 141. The suction passages 167, 167 that are located other than at both ends and the center in the axial direction of the developing roll 141 are closed by a shielding plate 171.

[0143] In addition, the exhaust passages 163, 163... are configured such that the suction passages 167, 167 blocked by the shielding plate 171 and the adjacent exhaust passages 163, 163... on both sides are blocked by the same shielding plate 171, and these blocked exhaust passages 163, 163... are connected to the blocked suction passages 167, 167 at their outlet ends via gaps.

[0144] In FIG. 13, for the sake of convenience, the shielding plate 171 is shown separated from the exhaust passages 163, 163... and the suction passages 167, 167; however, the shielding plate 171 is fixed to the device housing 140 by adhesive or other means, and blocks these exhaust passages 163, 163... and the suction passages 167, 167.

[0145] In the developing device of this embodiment 4, the outlet ends of the exhaust passages 163, 163... are blocked by a shielding plate 171 to prevent toner from leaking from the exhaust passages 163, 163... to the outside, and the exhaust passages 163, 163... are connected to the suction passages 167, 167, so that air inside the device housing 140 is discharged from the exhaust passages 163, 163... through the suction passages 167, 167, thereby ensuring the function of preventing or suppressing an increase in internal pressure.

[0146] Moreover, at both ends and the center of the developing roll 141 in the axial direction, the suction passages 167, 167... make it possible to reliably suck in toner that leaks to the outside.

[0147] The other configurations and operations are the same as those of the first embodiment, and therefore the description thereof will be omitted.

[0148] In the above embodiment, the case where the present invention is applied to a full-color image forming apparatus has been described, but it is needless to say that the present invention can also be applied to a monochrome image forming apparatus in the same manner.

[0149] In addition, in the above embodiment, a case has been described in which five suction passages are arranged along the axial direction of the developer carrier, but the number and arrangement of the suction passages are arbitrary, and it goes without saying that the number may be more or less than five.

[0150] (Additional Note) (((1))) A housing that contains a developer; a developer holding means that is disposed in an opening of the housing facing the image carrier and that holds the developer and rotates; an exhaust passage for discharging air within the housing to the outside; a suction passage for suctioning the developer leaking to the outside through an opening of the housing; Equipped with The developing device, wherein the exhaust passage and the suction passage are disposed at different positions along the axial direction of the developer holding means. (((2))) The developing device according to (((1))), wherein the suction passage is disposed downstream of the opening of the housing in the direction of rotation of the developer holding means. (((3))) The developing device according to (((1))), wherein the exhaust passage is disposed at an upper portion along a vertical direction of the housing. (((4))) The developing device described in (((3))), wherein the exhaust passage is located downstream in the rotational direction of the developer holding means at the opening of the housing and at the same position as the suction passage when viewed in the direction of the rotational axis of the developer holding means. (((5))) The developing device according to (((1))), wherein the suction passage is disposed at least at both ends in the axial direction of the developer holding means. (((6))) The developing device according to (((5))), wherein the suction passage is further disposed between the suction passages disposed at both ends in the axial direction of the developer holding means. (((7))) The developing device according to (((6))), wherein the suction passages are disposed at N equal intervals (N is an integer of 2 or more) along the axial direction of the developer holding means. (((8))) The developing device according to (((5))), wherein the exhaust passage is disposed at a position other than the suction passage along the axial direction of the developer holding means. (((9))) The developing device according to (((1))), wherein the exhaust passage is provided at an outlet thereof with a trapping means for trapping the developer leaking from the exhaust passage to the outside. (((10))) The developing device according to (((9))), wherein the trapping means is provided in all of the exhaust passages. (((11))) The developing device according to (((9))), wherein the capturing means is provided somewhere other than the exhaust passage adjacent to the suction passage. (((12))) The developing device according to (((1))), wherein a portion of the exhaust passage along the axial direction of the developer holding means is closed, and the closed exhaust passage communicates with the suction passage. (((13))) the suction passages are provided at a plurality of locations including both ends and a center portion along an axial direction of the developer holding means, The developing device described in (((12))) is characterized in that the exhaust passage adjacent to the suction passage arranged at a position excluding both ends and a central portion of the suction passage along the axial direction of the developer holding means is blocked. (((14))) an image holding means for holding an electrostatic latent image; a developing means for developing the electrostatic latent image on the image holding means; Equipped with An image forming apparatus using the developing device according to any one of ((1))) to (((13))) as the developing means.

[0151] According to the developing device of (((1))), it is possible to avoid increasing the size of the developing device, while simultaneously exhausting air from within the developing device and suctioning scattered toner, compared to a case in which the exhaust passage and the suction passage are arranged at the same position along the axial direction of the developer holding means. According to the developing device of (((2))), the suction passage can effectively suck in the developer discharged with the rotation of the developer holding means, compared to when the suction passage is positioned upstream in the rotation direction of the developer holding means at the opening of the housing. According to the developing device of (((3))), the exhaust passage can exhaust air from within the housing to the outside without interfering with the developer within the housing, compared to a case in which the exhaust passage is positioned at the bottom along the vertical direction of the housing. According to the developing device of (((4))), the exhaust passage is positioned in a different position from the suction passage along the rotation direction of the developer holding means, so that the developing device can be prevented from becoming large in size, compared to a case where the exhaust passage is positioned differently from the suction passage along the rotation direction of the developer holding means. According to the developing device of (((5))), the suction passage can effectively suck in developer leaking to the outside from the opening, compared to a case where the suction passage is not disposed at both ends along the axial direction of the developer holding means. According to the developing device of (((6))), it is easier to suck in developer leaking from an intermediate position along the axial direction of the developer holding means, compared to a case in which suction passages are arranged only at both ends along the axial direction of the developer holding means. According to the developing device of (((7))), the suction passage can evenly suck in developer leaking to the outside from the opening, compared to when the suction passage is arranged unevenly along the axial direction of the developer holding means. According to the developing device of (((8))), the exhaust passage overlaps partially or entirely with the position of the suction passage along the axial direction of the developer holding means, making it possible to avoid an increase in the size of the developing device. According to the developing device of (((9))), the exhaust passage can prevent developer from leaking from the exhaust passage, compared to a case in which the exhaust passage does not have a capturing means at its outlet portion for capturing developer leaking to the outside from the exhaust passage. According to the developing device of (((10))), the capturing means can reduce the amount of developer leaking from the exhaust passage, compared to when the capturing means is provided in a part of the exhaust passage. According to the developing device of (((11))), the trapping means can suppress a reduction in the exhaust effect caused by clogging of the trapping means with developer, compared to a case in which the trapping means is provided in all exhaust passages. According to the developing device of (((12))), the exhaust effect of the exhaust passage can be maintained as compared with the case where the exhaust passage is simply blocked. According to the developing device of (((13))), it is possible to more effectively exhaust air from within the developing device and to suction scattered toner, compared to a case in which the exhaust passage is blocked regardless of the position of the suction passage. According to the image forming apparatus of (((14))), it is possible to both exhaust air from within the developing device and suck up scattered toner, compared to a case in which a developing device described in any of (((1))) to (((13))) is not used as the developing means. [Explanation of symbols]

[0152] 1...Image forming device 1a…Device body 11...Photoconductor drum 14...Developing device 140...Device housing 141...Developing roll 142...Agitation supply member 143...Agitation and conveying member 151…Opening 163…Exhaust passage 167...Suction passage

Claims

1. A housing that contains a developer; a developer holding means that is disposed in an opening of the housing facing the image carrier and that holds the developer and rotates; an exhaust passage for discharging air within the housing to the outside; a suction passage for suctioning the developer leaking to the outside through an opening of the housing; Equipped with The developing device, wherein the exhaust passage and the suction passage are disposed at different positions along the axial direction of the developer holding means.

2. 2. The developing device according to claim 1, wherein the suction passage is disposed downstream of the opening of the housing in the direction of rotation of the developer holding means.

3. The developing device according to claim 1 , wherein the exhaust passage is disposed in an upper portion along a vertical direction of the housing.

4. 4. The developing device according to claim 3, wherein the exhaust passage is disposed downstream in the rotational direction of the developer holding means from the opening of the housing and at the same position as the suction passage when viewed in the direction of the rotational axis of the developer holding means.

5. 2. The developing device according to claim 1, wherein the suction passages are disposed at least at both ends in the axial direction of the developer holding means.

6. 6. The developing device according to claim 5, wherein the further suction passage is disposed between the suction passages disposed at both ends in the axial direction of the developer holding means.

7. 7. The developing device according to claim 6, wherein the suction passages are disposed at N equal intervals (N is an integer of 2 or more) along the axial direction of the developer holding means.

8. 6. The developing device according to claim 5, wherein the exhaust passage is disposed at a position other than the suction passage along the axial direction of the developer holding means.

9. 2. The developing device according to claim 1, wherein the exhaust passage has, at an outlet thereof, trapping means for trapping the developer leaking from the exhaust passage to the outside.

10. 10. The developing device according to claim 9, wherein the trapping means is provided in all of the exhaust passages.

11. 10. The developing device according to claim 9, wherein the trapping means is provided in a location other than the exhaust passage adjacent to the suction passage.

12. 2. The developing device according to claim 1, wherein a portion of the exhaust passage along the axial direction of the developer holding means is closed, and the closed exhaust passage communicates with the suction passage.

13. the suction passages are provided at a plurality of locations including both ends and a center portion along an axial direction of the developer holding means, 13. The developing device according to claim 12, wherein the exhaust passage is closed at a position adjacent to the suction passage except for both ends and a central portion of the suction passage in the axial direction of the developer holding means.

14. an image holding means for holding an electrostatic latent image; a developing means for developing the electrostatic latent image on the image holding means; Equipped with An image forming apparatus using the developing device according to any one of claims 1 to 13 as the developing means.

Images