JP2010054932A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively suppress a toner leak resulting from an increase in internal pressure while reducing the cost of parts and running cost. <P>SOLUTION: The developing device is attached to a printer 10 and performs a developing process on the circumferential face of a photoreceptor drum 121 by supplying toner toward the circumferential face. The developing device has, in a prescribed casing 21, first and second developing rollers 41 and 42, which supply filled toner toward the photoreceptor drum 121, and first and second spiral feeders 31 and 32, which convey toner toward the first and the second developing rollers 41 and 42 while stirring the toner. In addition, a top plate 232 for the casing 21 is provided with ducts 50 communicating with the outside in order to let pressure in the casing 21 out. A meandering passage 262 is formed in each duct 50. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device arranged in an image forming apparatus and configured to supply toner toward an image carrier, and an image forming apparatus to which the developing device is applied.

  Conventionally, a developing device applied to an image forming apparatus as described in Patent Document 1 is known. This developing device supplies toner to the peripheral surface of a photosensitive drum as an image carrier to form a toner image along an electrostatic latent image previously formed on the peripheral surface of the photosensitive drum. . In such a developing device, a stirring screw for stirring the toner in the developing tank is provided, and the toner is stirred toward the developing sleeve provided with a magnet inside while being stirred. Be transported. The toner that has reached the developing sleeve forms a magnetic brush as a magnetic brush by the cooperation of the rotation of the developing sleeve and the magnet. Therefore, the outside air is attracted and developed by the rotation of the magnetic brush and the rotation of the stirring screw. The pressure in the tank rises.

  Then, when the pressure in the developing device rises, the air in the developing tank is discharged to the outside through the gap, so that the toner leaks to the outside accompanying the air flow, and the inside of the image forming apparatus Inconvenient contamination will occur.

  In order to eliminate such inconvenience, in the developing device of Patent Document 1, a duct provided with a filter is attached to the developing device, and air in the developing device is sucked through the duct by driving a suction fan. Has been made. In this way, an increase in pressure in the developing device is suppressed, and the toner accompanying the airflow is captured by the filter, so that the toner is prevented from scattering out of the developing device.

In addition to Patent Document 1, the one described in Patent Document 2 is also known as a means for preventing toner leakage from the developing device. In the device described in Patent Document 2, a rotary cylindrical air filter and a brush for cleaning toner adhering to the air filter are provided on a top plate of a casing of a developing device.
JP-A-8-220882 JP 2007-248629 A

  However, the developing device described in Patent Document 1 has a problem in that the filter is easily clogged and the running cost increases due to the replacement of the old and new filters. Further, the developing device according to claim 2 has a complicated structure such as a rotary cylindrical air filter and a brush for cleaning toner adhering to the air filter. In addition, there is a problem that the cost of parts increases.

  The present invention has been made in view of the above situation, and can reduce the leakage of toner due to an increase in internal pressure while reducing component costs and running costs. It is another object of the present invention to provide an image forming apparatus.

  According to a first aspect of the present invention (developing device), a casing that accommodates toner, a stirring and conveying member that is disposed in the casing and conveys the toner while stirring, and is formed at a predetermined position of the casing, the casing is provided. A pressure relief hole for releasing the internal pressure, and a duct portion having a flow path whose one end side is connected to the pressure relief hole and whose other end side is opened to the outside. It is a meandering flow path meandering toward the end side.

  According to such a configuration, the pressure in the casing rises due to entrainment of outside air by driving the agitating and conveying member or temperature rise due to frictional heat or the like generated by conveying the toner, so that the internal air passes through the duct portion. Derived outside. At this time, since the duct portion for leading the air to the outside through the pressure release hole is a meandering passage having a meandering passage, the toner contained in the air flow from the inside of the casing to the outside is meandering. It is removed from the airflow by the action of so-called inertia dust collection that collides with the inner wall surface of the duct part and sinks in the middle of the flow path. Therefore, the air stream that has been cleaned by removing the toner from the duct portion is discharged into the image forming apparatus.

  According to a second aspect of the present invention, in the first aspect of the present invention, the duct portion is provided on an upper surface side of the casing.

  According to such a configuration, since the duct portion is provided on the upper surface side of the casing, the air flow including the toner toward the duct portion in the casing rises, so that the interference of the air flow with other toners is minimized. The increase in the amount of entrained toner in the airflow is suppressed.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein a plurality of the pressure release holes are formed in the casing, and one end side of the duct portion covers all of the plurality of pressure release holes. It is characterized by being formed.

  According to this configuration, since the plurality of pressure relief holes formed in the casing are all covered by the one end side of the duct portion, all the air including the toner discharged through the pressure relief hole is ducted. It is trapped inside and the toner is removed and cleaned.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the duct portion is erected upward from the casing so as to face each other across the pressure release hole. A wall including a wall and a second wall, and the flow path is formed between the opposed surfaces of the first wall and the second wall, and a first plate projects from the opposed surface of the first wall toward the second wall A second plate protrudes from the opposing surface of the second wall toward the first wall, and a space is provided between the front ends of the first plate and the second plate and the opposing surface of the counterpart. And the said 1st board and the said 2nd board differ in the protruding height position, It is characterized by the above-mentioned.

  According to such a configuration, when the meandering flow path is formed in the duct portion, the first and second walls are erected in the upward direction so as to form the flow path from the casing so as to face each other with the pressure release hole interposed therebetween. By projecting the first and second plates having different height positions from the first and second walls toward the mating side, a meandering flow path is formed at a low cost with a simple structure. Therefore, the apparatus cost can be reduced as compared with the case where the duct part itself meanders.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, a wall plate is provided at an upper position of the casing so as to form a concave portion facing a wall surface extending in the vertical direction of the casing. It is a first wall, and the wall plate is the second wall.

  According to such a configuration, by forming the duct portion using the wall surface extending in the vertical direction of the casing, it is possible to save the material for forming the duct portion and contribute to the reduction of the apparatus cost. To do.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, further comprising a lid attached to the other end side of the duct portion and having a plurality of slits. It is.

  According to such a configuration, since the other end side of the duct portion is closed by the lid body having a plurality of slits, foreign matter from the other end portion is mixed into the duct while ensuring the discharge of the airflow through the slits. Is prevented.

  A seventh aspect of the present invention (an image forming apparatus) is an image carrier that carries a toner image, and a developing device according to any one of the first to sixth aspects that supplies toner toward the surface of the image carrier. It is characterized by including.

  According to this configuration, the image forming apparatus can enjoy the functions and effects of the developing device according to claims 1 to 6.

  According to the developing device of the present invention, the simple configuration of meandering the flow path of the duct portion provided on the top plate of the casing effectively uses the conventional technique while effectively preventing the toner from scattering from the casing. As a result, the number of parts can be reduced by not using the filter or the like that has been used, and as a result, the manufacturing cost and running cost of the developing device can be reduced.

  Further, according to the image forming apparatus of the present invention, the image forming apparatus can enjoy the function and effect of the developing device according to claims 1 to 6.

  First, an outline of an internal structure of a printer (image forming apparatus) 10 to which a developing device according to the present invention is applied will be described with reference to FIG. FIG. 1 is an explanatory diagram of a front cross-sectional view for explaining an embodiment of the internal structure of the printer 10. In FIG. 1, the XX direction is referred to as the left-right direction, and in particular, the -X direction is referred to as the left, and the + X direction is referred to as the right.

  As shown in FIG. 1, the printer 10 of the present embodiment includes an image forming unit 12 that forms an image based on image information transmitted from an external device such as a computer in a box-shaped main body 11, and this image. A fixing unit 13 that performs a fixing process on the image formed by the forming unit 12 and transferred to the paper P, and a paper storage unit 14 that stores the transfer paper are provided in the interior of the apparatus main body 11. A basic configuration is formed by forming a paper discharge portion 15 for discharging the paper P after the fixing process.

  At an appropriate position on the upper surface of the apparatus main body 11, an operation panel (not shown) for inputting the output conditions of the paper P and the like is provided. This operation panel is provided with a power key, a start button (not shown), various keys for inputting output conditions, and the like.

  The image forming unit 12 is a part where an image forming process is performed to form a toner image on the paper P fed from the paper storage unit 14. In this embodiment, the image forming unit 12 includes a magenta unit 12M using a magenta developer and a cyan developer arranged sequentially from the upstream side (right side in FIG. 1) to the downstream side. 12C, a yellow unit 12Y using a yellow developer, and a black unit 12K using a black developer.

  Each of the units 12M, 12C, 12Y, and 12K is provided with a photosensitive drum 121 and a developing device 20, respectively. The photosensitive drum 121 is for forming an electrostatic latent image and a toner image (visible image) along the electrostatic latent image on the peripheral surface. Each photosensitive drum 121 receives supply of developer from the corresponding developing device 20 while rotating counterclockwise in FIG. Each developing device 20 is replenished with a developer from a toner cartridge (not shown) disposed on the front side of the apparatus main body 11 (the front side of the paper surface of FIG. 1).

In the present embodiment, a so-called two-component developer composed of toner and carrier is used as the developer. The toner is a fine powder having a particle diameter of 6 to 12 μm in which additives such as a colorant, a charge control agent and wax are dispersed in a binder resin. On the other hand, the carrier is magnetic particles having a particle size of 60 to 200 μm such as magnetite (Fe ₃ O ₄ ), and is used for charging the toner. The toner is a consumable that is appropriately replenished to the developing device 20 from a toner cartridge (not shown), whereas a predetermined amount of the carrier is loaded in the developing device 20 in advance, and is used without being consumed. It is common to be done.

  Since the carrier in the developer has a larger particle size and weight than the toner, it is difficult for the carrier to leak from the inside of the developing device 20, whereas the toner is scattered because the particle size and weight are small. It is easy to leak from 20 to the outside. The present invention can effectively prevent such toner leakage.

  A charging device 122 is provided immediately below each photoconductor drum 121, and an exposure device 123 is provided further below each charging device 122. Each photosensitive drum 121 is charged uniformly by the charging device 122, and laser light corresponding to each color based on image data input from a computer or the like is charged from each exposure device 123 after being charged. By irradiating the peripheral surface of the photosensitive drum 121, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 121. By supplying the developer from the developing device 20 to the electrostatic latent image, a toner image is formed on the peripheral surface of the photosensitive drum 121.

  A transfer belt 124 stretched between the driving roller 124 a and the driven roller 124 b is provided at a position above the photosensitive drum 121 so as to be in contact with each photosensitive drum 121. The transfer belt 124 is driven against a peripheral surface of the photoconductive drum 121 by a transfer roller 125 provided corresponding to each photoconductive drum 121, and is driven with a drive roller 124 a and a driven roller while being synchronized with the photoconductive drum 121. It goes around between 124b.

  Accordingly, when the transfer belt 124 rotates, the toner image of the magenta toner is transferred to the surface of the transfer belt 124 by the photosensitive drum 121 of the magenta unit 12M, and then the photosensitive member of the cyan unit 12C is located at the same position of the transfer belt 124. The transfer of the cyan toner image by the drum 121 is performed in the overcoating state, and the transfer of the yellow toner image by the photosensitive drum 121 of the yellow unit 12Y is performed in the overcoating state at the same position on the transfer belt 124. Then, the transfer of the black toner image by the photosensitive drum 121 of the last black unit 12K is performed in an overcoated state, whereby a color toner image is formed on the surface of the transfer belt 124. The color toner image formed on the surface of the transfer belt 124 is transferred to the paper P conveyed from the paper storage unit 14.

  A cleaning device 126 that removes and cleans residual toner on the peripheral surface of the photosensitive drum 121 is provided at the left position of each photosensitive drum 121 in FIG. The peripheral surface of the photosensitive drum 121 cleaned by the cleaning device 126 goes to the charging device 122 for a new charging process.

  The waste toner removed from the peripheral surface of the photosensitive drum 121 by the cleaning device 126 is collected and stored in a toner collection bottle (not shown) through a predetermined path.

  At the left position of the image forming unit 12 in FIG. 1, a paper conveyance path 111 extending in the vertical direction is formed. A predetermined pair of conveyance roller pairs 112 are provided in appropriate positions on the sheet conveyance path 111, and a transfer belt 124 on which sheets from the sheet storage unit 14 are wound around a driving roller 124 a by driving these conveyance roller pairs 112. It is conveyed toward. In the sheet conveyance path 111, a second transfer roller 113 that is in contact with the surface of the transfer belt 124 is provided at a position facing the driving roller 124 a, and the sheet P being conveyed along the sheet conveyance path 111 is in contact with the transfer belt 124. The toner image on the transfer belt 124 is transferred onto the paper P by being pressed and sandwiched between the second transfer roller 113 and the second transfer roller 113.

  The fixing unit 13 performs a fixing process on the toner image on the paper transferred by the image forming unit 12, and includes a heating roller 131 including an energization heating element such as a halogen lamp as a heating source, 1, a fixing roller 132 arranged to face the heating roller 131 on the left side, a fixing belt 133 stretched between the fixing roller 132 and the heating roller 131, and the fixing roller 133 via the fixing belt 133. 40 and a pressure roller 134 disposed to face the surface 40.

  The sheet P supplied to the fixing unit 13 in a state where the toner image on the transfer belt 124 is transferred by passing through the nip portion between the transfer belt 124 and the second transfer roller 113 is supplied to the pressure roller 134. Then, the fixing process is performed by obtaining heat from the fixing belt 133 while passing between the toner and the high-temperature fixing belt 133.

  The paper P with the color image for which the fixing process has been completed passes through a paper discharge conveyance path 114 extending from the upper part of the fixing unit 13 to a paper discharge tray 151 of a paper discharge unit 15 provided at the top of the apparatus main body 11. It is discharged towards.

  The sheet storage unit 14 includes a manual feed tray 141 that can be freely opened and closed on the right side wall in FIG. 1 of the apparatus main body 11, and a paper tray 142 that is removably mounted at a position below the exposure device 123 in the apparatus main body 11. And is configured. A sheet bundle is stored in the sheet tray 142.

  The manual feed tray 141 is for manually feeding the paper P one by one toward the image forming unit 12 by manual feed operation, and is usually stored on the rear wall surface in FIG. As shown in FIG. 1, only when the paper is fed, the paper is pulled out from the wall surface and used for manual paper feeding.

  The paper tray 142 includes a box body whose upper surface is open on the entire surface, and can store a sheet bundle P1 formed by stacking a plurality of sheets P. The uppermost sheet P of the sheet bundle P1 stored in the sheet tray 142 is fed out from the sheet bundle P1 toward the sheet conveyance path 111 by driving the pickup roller 143 from the downstream end (left end in FIG. 1). The sheet P is fed out one by one, and the sheet P passes through the sheet conveyance path 111 by the driving of the conveyance roller pair 112 toward the nip portion between the second transfer roller 113 and the transfer belt 124 in the image forming unit 12. It is sent.

  Hereinafter, the developing device 20 according to this embodiment will be described with reference to FIGS. 2 and 3 are perspective views showing an embodiment of the developing device 20 according to the present invention. FIG. 2 is an overall perspective view, and FIG. 3 shows the developing device 20 shown in FIG. It is a fracture | rupture perspective view of the state fractured | ruptured in the approximate center part. 4 is a cross-sectional view taken along line IV-IV in FIG. 2 to 4, the XX direction is referred to as the left-right direction, and the YY direction is referred to as the front-rear direction. In particular, the -X direction is leftward, the + X direction is rightward, the -Y direction is frontward, and the + Y direction is rearward. That's it.

  As shown in FIGS. 2 to 4, the developing device 20 according to the present embodiment includes a toner stirring mechanism 30 that stirs the developer in a casing 21 that is long in the front-rear direction, and a stirring process by the toner stirring mechanism 30. A toner supply mechanism 40 for supplying the developed developer toward the peripheral surface of the photosensitive drum 121, and a duct portion 50 that prevents the toner from leaking from the casing 21 while communicating with the inside and outside of the casing 21. It is configured.

  As shown in FIG. 2, the casing 21 has a length dimension (front-rear dimension) slightly longer than the sheet width dimension of the sheet P to be conveyed. As shown in FIG. 3, the casing 21 includes a lower casing 22 to which the toner agitating mechanism 30 is attached, and an upper casing 23 provided on the lower casing 22 to which the toner supply mechanism 40 is attached. It consists of a two-stage structure consisting of A gear mechanism 29 for transmitting a driving force from a drive motor (not shown) to the toner stirring mechanism 30 and the toner supply mechanism 40 is provided at the rear end of the casing 21.

  The lower casing 22 has a left-right width dimension set longer than that of the upper casing 23. The lower casing 22 has an arcuate arc-shaped wall 221 that protrudes toward the upper right in a front view from the −Y direction in which the right end protrudes rightward from the right end of the upper casing 23, and A lower left wall 222 is provided at the left end position, and a bottom plate 223 is installed between the lower edge of the arc wall 221 and the lower edge of the lower left wall 222.

  These arc wall 221, lower left wall 222, and bottom plate 223 are all constructed between a front wall member 211 and a rear wall member 212 (FIG. 2) as structural members.

  In the lower casing 22, as shown in FIGS. 3 and 4, a partition wall 25 extending in the front-rear direction is provided at the central portion in the left-right direction, and the interior of the lower casing 22 is divided into right and left by the partition wall 25. . A first spiral feeder (stirring conveyance member) 31 described later is provided on one side (right side) of the lower casing 22 which is divided into two, and a second spiral feeder (described later) is provided on the other side (left side). A stirring and conveying member) 32 is provided.

  The upper casing 23 includes an inclined wall (first wall) 231 inclined upward from the left edge of the arc wall 221 of the lower casing 22 and forward from the upper edge of the inclined wall 231. A top plate 232 that extends horizontally toward the top, and an upper left wall 233 that extends upward from the upper edge of the lower left wall 222 of the lower casing 22.

  The inclined wall 231, the top plate 232, and the upper left wall 233 are all constructed between the front wall member 211 and the rear wall member 212 as structural members.

  The upper casing 23 has a predetermined vertical dimension between the front edge of the top plate 232 and the upper edge of the upper left wall 233 on the front surface in FIGS. A toner supply opening 234 facing the peripheral surface of the body drum 121 is opened, and the developer fed into the upper casing 23 is driven by the toner supply mechanism 40 to the peripheral surface of the photosensitive drum 121 via the toner supply opening 234. Supplied.

  In addition, a vertical wall (second wall) 235 is erected on the upper casing 23 from the base end portion of the inclined wall 231 upward. The vertical wall 235 is installed between the front and rear wall members 211 and 212, thereby forming a V-shaped groove 26 extending in the front-rear direction between the vertical wall 235 and the inclined wall 231. A duct portion 50 including the V-shaped groove 26, which will be described in detail later, is formed.

  As shown in FIGS. 3 and 4, the toner agitating mechanism 30 includes a first spiral feeder 31 extending in the front-rear direction at a right position from the partition wall 25 in the lower casing 22, and a first spiral feeder on the left side from the partition wall 25. 31 and a second spiral feeder 32 disposed in parallel with each other. The developer supplied from the toner cartridge into the lower casing 22 through a developer receiving opening (not shown) is conveyed forward by the drive rotation of the first spiral feeder 31.

  On the other hand, the partition wall 25 is provided with communication openings 251 (FIG. 4) at the left end and the right end, respectively. Then, the developer transported forward through the space on the right side of the partition wall 25 in the lower casing 22 by driving the first spiral feeder 31 is carried into the space on the left side of the partition wall 25 through the front connection opening 251. The Part of the developer carried into the left space is formed between the left side of the partition wall 25 of the lower casing 22 and the upper casing 23 while being conveyed rearward by driving the second spiral feeder 32. The first developing roller 41, which will be described later, passes through the long pumping space 27 in the front-rear direction and is pumped toward the upper casing 23 by the driving rotation toward the clockwise direction. On the other hand, the remaining portion that has not been pumped is returned to the space on the right side of the partition wall 25 through the rear connection opening 251 and circulated and conveyed.

  The toner supply mechanism 40 is for pumping the toner from the lower casing 22 into the upper casing 23 by driving the toner stirring mechanism 30 and for supplying the pumped toner to the photosensitive drum 121. The toner supply mechanism 40 includes a first developing roller 41 extending in the front-rear direction disposed opposite to the position directly above the second spiral feeder 32 on the lower right side of the upper casing 23, and the first developing roller 41 in the upper casing 23. A second developing roller 42 that is disposed diagonally to the left in parallel with the first developing roller 41 and whose peripheral surfaces face each other with a slight gap therebetween, and a leading edge is the first developing roller And a layer thickness regulating member 43 disposed to face the left surface of 41 with a predetermined gap therebetween.

  The layer thickness regulating member 43 regulates the developer that is pumped up from the pumping space 27 by the clockwise rotation around the axis of the first developing roller 41 and adheres to the peripheral surface of the first developing roller 41 to a predetermined thickness. To do. That is, the developer attached to the peripheral surface of the first developing roller 41 according to the rotation of the first developing roller 41 is between the leading edge of the layer thickness regulating member 43 and the peripheral surface of the first developing roller 41. By diving through the gap, the developer supplied to the second developing roller 42 has a preset layer thickness.

  The first developing roller 41 is pivotally supported around the first roller shaft 411 passing through the front wall member 211 and the rear wall member 212 (FIG. 2) so as to be relatively rotatable and the second developing roller 42 is The second roller shaft 421 is rotatably supported concentrically.

  The first developing roller 41 rotates relative to the first roller shaft 411 in the clockwise direction when the driving force of a drive motor (not shown) is transmitted to the first roller shaft 411 via the gear mechanism 29. At the same time, the second developing roller 42 is driven by the rotation of the first developing roller 41 via the gear mechanism 29 (not shown), and rotates synchronously around the second roller shaft 421 in the clockwise direction.

  As shown in FIG. 4, the first developing roller 41 is a thin layer formed on the peripheral surface, and a cylindrical sleeve 41a made of nonmagnetic material such as aluminum, and the sleeve 41a are externally fitted. It consists of a cylindrical magnet body 41b. The sleeve 41a is concentrically rotatable with the first roller shaft 411, while the cylindrical magnet body 41b is mounted on the casing 21 so as not to rotate due to the D cut at the end. This prevents the sleeve 41a from rotating even if the sleeve 41a rotates.

  FIG. 4 shows the peak positions of the magnetic poles of the cylindrical magnet body 41b. That is, the cylindrical magnet body 41b is formed with the first N pole N1 formed from the first roller shaft 411 toward the second developing roller 42 and the first roller shaft 411 facing upward substantially vertically. The first S pole S1, the second N pole N2 formed obliquely to the right from the first roller shaft 411 on the right side of the first S pole S1 in FIG. 4, and the first roller shaft The second S pole S2 formed substantially horizontally from 411 toward the right in FIG. 4, the third S pole S3 formed substantially vertically downward from the first roller shaft 411, and the first roller shaft A third N pole N3 formed obliquely to the left in FIG. 4 downward from 411, and a fourth S pole S4 formed substantially horizontally from the first roller shaft 411 toward the left in FIG. Are set respectively.

  On the other hand, inside the second developing roller 42, a magnet having a counter electrode (specifically, an S electrode) facing the first N pole N1 is provided at a position facing the first developing roller 41. . As in the case of the first developing roller 41, the magnet is configured not to rotate even when the sleeve forming the peripheral surface portion of the second developing roller 42 rotates.

  The developer pumped up to the peripheral surface of the sleeve 41a at the position of the third S pole S3 by the clockwise rotation around the first roller shaft 411 of the sleeve 41a causes the third N pole N3 and the third N pole N3. It passes through the layer thickness regulating member 43 at a position between the 4 s poles S4, and thereby the layer thickness is regulated. The developer whose layer thickness is regulated is conveyed to the position of the first N pole N1 facing the second developing roller 42 via the position of the fourth S pole S4, where the developer is opposed to the first N pole N1. A toner layer is formed on the peripheral surface of the second developing roller 42 by being attracted to the opposite electrode of the second developing roller 42. The toner layer is conveyed to a position facing the photosensitive drum 121 by the rotation of the second developing roller 42 around the second roller shaft 421, and is supplied to the peripheral surface of the photosensitive drum 121 here.

  The developer containing toner that has not been attracted to the peripheral surface of the second developing roller 42 from the peripheral surface of the sleeve 41a at the position of the first N pole N1 is rotated by the clockwise rotation of the sleeve 41a. Then, it passes through the positions of the second N pole N2 and the second S pole S2, and is collected on the left side (that is, the pumping space 27) of the partition wall 25 of the lower casing 22 in FIG. The toner that has not been supplied from the second developing roller 42 to the photosensitive drum 121 is returned to the peripheral surface of the sleeve 41a of the first developing roller 41 while being rubbed with the magnetic brush, and is collected in the pumping space 27 in the same manner as described above. Is done. In this case, in this embodiment, a wide distance is secured between the second S pole S2 and the third S pole S3, thereby forming a non-magnetic pole region between the second and third S poles S2 and S3. Therefore, the developer that has passed through the fourth S pole S4 is easily peeled off from the peripheral surface of the sleeve 41a without being affected by the magnetic force.

  Even when the distance between the second and third S poles S2 and S3 cannot be secured sufficiently large, the developer positioned between the second and third S poles S2 and S3 is between the same poles. Are easily peeled off from the peripheral surface of the sleeve 41a.

  A positioning roller 44 (indicated by a two-dot chain line in FIG. 4) is externally fitted on both ends of the second roller shaft 421 that supports the second developing roller 42 so as to be relatively rotatable. . The positioning roller 44 is set to have an outer diameter dimension slightly larger than the outer diameter dimension of the second developing roller 42, so that the pair of left and right positioning rollers 44 are in contact with the peripheral surface of the photosensitive drum 121. A gap having a predetermined size is formed between the peripheral surface of the second developing roller 42 and the peripheral surface of the photosensitive drum 121. The toner in the developer stacked on the peripheral surface of the second developing roller 42 is supplied to the peripheral surface of the photosensitive drum 121 through this gap.

  Hereinafter, the duct portion 50 attached to the developing device 20 configured as described above will be described with reference to FIGS. 5 and 6. 5 and 6 are perspective views showing an embodiment of the duct portion 50, FIG. 5 is an exploded perspective view, and FIG. 6 is an assembly view. And especially about FIG. 6, FIG. 6 (A) is an assembly perspective view, and FIG. 6 (B) is sectional drawing of FIG. 6 (A). 5 and 6 are the same as those shown in FIG. 2 (-X: leftward, + X: rightward, -Y: forward, + Y: backward).

  First, as shown in FIG. 5, the duct portion 50 is fixed to the V-shaped groove 26 formed by the inclined wall 231 and the vertical wall 235 of the casing 21 and the vertical wall 235 side of the V-shaped groove 26. The lower baffle plate 51 covering the entire length of the V-shaped groove 26, a lid body 52 for closing the upper surface opening of the V-shaped groove 26, and the total length of the lid body 52 projecting downward from the back surface of the lid body 52 And a top baffle plate 54 that extends from the right surface of the drooping plate 53 toward the right side and extends over the entire length of the drooping plate 53. The inclined wall 231 constitutes a part of the top plate according to the present invention.

  A plurality of flow holes (pressure release holes) 261 arranged in parallel at a predetermined pitch in the front-rear direction are provided at a position below the inclined wall 231 in the V-shaped groove 26. The airflow generated in the casing 21 is introduced into the V-shaped groove 26 through the flow hole 261 and discharged to the outside through the meandering flow path 262 in the V-shaped groove 26.

  The lower baffle plate 51 is attached to the left side of the substantially central portion of the vertical wall 235 in the vertical direction. The lower baffle plate 51 has an extended portion 511 extending downward from the right edge portion thereof, and the extended portion 511 is fixed to the vertical wall 235 by screws or the like, so that the lower baffle plate 511 is fixed. A plate 51 is mounted in the V-shaped groove 26. Such a lower baffle plate 51 is set such that the plate width dimension in the left-right direction is slightly shorter than the groove width dimension of the V-shaped groove 26 at the attachment position. Therefore, a flow path through which airflow is passed between the left edge of the lower baffle plate 51 and the right surface of the inclined wall 231 is formed in the V-shaped groove 26.

  The lid body 52 is set to be slightly shorter than the inner dimension between the front wall member 211 (see FIG. 2, not shown in FIGS. 5 and 6) and the rear wall member 212 of the casing 21. In addition, the width dimension in the left-right direction is set slightly larger than the left-right dimension of the upper surface opening of the V-shaped groove 26.

  On the other hand, a square groove 231a cut at a right angle is provided at the same height position as the upper edge surface of the vertical wall 235 in the inclined wall 231. The lid body 52 is in a state in which the V-shaped groove 26 is closed by the left edge portion being fitted into the square groove 231 a and the right edge portion being supported by the upper edge portion of the vertical wall 235.

  Further, the front and rear wall members 211 and 212 are respectively provided with protrusions 213 whose upper surfaces are at the same height as the upper edge surface of the vertical wall 235 in the opposing direction (see FIGS. 5 and 5). 6, illustration of the protrusion 213 on the front wall member 211 side is omitted. Positioning protrusions 213a that protrude upward are provided on the upper surfaces of the protrusions 213, respectively.

  On the other hand, positioning holes 521 that are externally fitted to the positioning projections 213a are formed in the front and rear end portions of the lid body 52 at positions corresponding to the positioning projections 213a. Therefore, by fitting each positioning hole 521 to the corresponding positioning projection 213a, the lid 52 can close the upper surface opening of the V-shaped groove 26 in a state where the positional deviation is prevented.

  Further, a pair of front and rear locking plate pieces 522 project in an overhanging state at appropriate positions on the right edge surface of the lid body 52. Each locking plate piece 522 has a locking hole 522a drilled in the center.

  On the other hand, locking projections 235a having an inclined surface on the upper surface, on which the locking holes 522a are externally fitted, are provided at positions corresponding to the locking plate pieces 522 on the vertical wall 235, respectively. Then, the locking holes 522a of the respective locking plate pieces 522 are fitted into the corresponding locking projections 235a, so that the lid body 52 is in a V-shaped groove in the state of being prevented from coming off as shown in FIG. 26 will be attached.

  Further, a large number of slits 523 that are long in the left-right direction are juxtaposed in the front-rear direction at the center position in the left-right direction of the lid 52. The airflow introduced into the V-shaped groove 26 through the flow hole 261 is discharged to the outside through these slits 523.

  The drooping plate 53 is provided at a position that is shifted to the right by the left and right width dimension of the inclined wall 231 from the left end edge on the back surface side of the lid body 52. The vertical dimension of the hanging plate 53 is set to be substantially equal to the distance between the upper edge portion of the vertical wall 235 and the lower baffle plate 51.

  The upper baffle plate 54 is provided so as to protrude rightward from the center of the hanging plate 53 in the vertical direction. The left-right width dimension of the upper baffle plate 54 is set slightly shorter than the inner dimension between the hanging plate 53 and the vertical wall 235.

  In the state where the lid 52 closes the upper surface opening of the V-shaped groove 26, as shown in FIGS. 6A and 6B, meandering from the flow hole 261 to the slit 523 in the V-shaped groove 26. A flow path 262 is formed.

  Therefore, when the developing device 20 is in operation, it becomes higher due to air entrainment due to driving of the first and second spiral feeders 31 and 32 and an increase in the temperature of the air in the casing 21 due to frictional heat during toner stirring. As for the pressure in the casing 21, the air in the casing 21 becomes an air flow due to the stop of the entrainment of outside air due to the stop of the developing device 20, and is discharged to the outside through the V-shaped groove 26.

  At this time, a part of the toner flows out of the casing 21 along with the airflow, but the airflow introduced into the V-shaped groove 26 through the flow hole 261 enters the V-shaped groove 26. The toner in the airflow collides with the lower baffle plate 51 and the upper baffle plate 54 and falls or adheres because it passes through the meandering flow path 262 formed by the lower baffle plate 51 and the upper baffle plate 54. As a result, the toner in the airflow discharged from the slit 523 to the outside is reduced.

  Thus, by providing the duct portion 50 in which the meandering flow path 262 is formed in the V-shaped groove 26, even if the air flow from the inside of the casing 21 is discharged to the outside through the V-shaped groove 26, it is accompanied by the air flow. Since the toner is removed, it is possible to effectively prevent the occurrence of inconvenience that the space in the printer 10 is contaminated with the scattered toner.

  As described above in detail, the developing device 20 according to the present invention is mounted on the printer 10 and applies toner to the peripheral surface of the photosensitive drum 121 to perform development processing on the peripheral surface. First and second developing rollers 41 and 42 that supply the filled toner toward the photosensitive drum 121, and first and second toners that are conveyed to the first and second developing rollers 41 and 42 while stirring. The second spiral feeders 31 and 32 are housed in a predetermined casing 21, and the top plate 232 of the casing 21 is provided with a duct portion 50 communicating with the outside in order to release the pressure in the casing 21. A serpentine flow path 262 is formed in the portion 50.

  According to the developing device 20 having such a configuration, the first and second spiral feeders 31 and 32 can be moved even if the inside of the casing 21 is driven by the rotation of the first and second spiral feeders 31 and 32 and the pressure is increased. When the air flow is stopped, the internal air is led out to the outside through the duct portion 50. However, since the meandering flow path 262 is formed in the duct portion 50, it is included in the air flow from the inside of the casing 21 to the outside. The toner that is in the meandering collides with the inner wall surface of the duct portion 50 during the meandering and sinks, so that a so-called inertia dust collecting function is exhibited.

  In this way, the simple configuration of meandering the flow path of the duct portion 50 effectively prevents the toner from scattering from the casing 21 of the developing device to the outside, and uses a conventionally used filter or the like. As a result, the manufacturing cost and running cost can be reduced, and as a result, the manufacturing cost and running cost of the developing device 20 can be reduced.

  And since the duct part 50 is provided in the upper surface side of the casing 21, the airflow containing the toner which goes to the duct part 50 in the casing 21 will rise, and interference with the other toner of airflow will be the minimum. The increase in the amount of entrained toner in the airflow can be suppressed.

  The inclined wall (top plate) 231 has a plurality of flow holes 261 formed therein, and the duct portion 50 is formed so as to cover all the flow holes 261. Therefore, the first and second spiral feeders 31, By preventing the inconvenience of the toner from jumping up and being discharged to the outside from the duct portion 50 by driving 32, only the air flow can be led out through the plurality of flow holes 261.

  In the above embodiment, the duct portion 50 includes the inclined wall 231 extending from the top plate 232, the vertical wall 235 erected so as to face the inclined wall 231, and the inclined wall 231 and Since the lower baffle plate 51 and the upper baffle plate 54 projecting toward each other so as to form a staggered shape from the vertical wall 235 are provided, the duct portion 50 itself is bent and entirely meandered. In comparison, the meandering flow path 262 can be formed with a simple structure at low cost.

  The present invention is not limited to the above embodiment, and includes the following contents.

  (1) In the above embodiment, the printer 10 is described as an example of the image forming apparatus to which the developing device 20 according to the present invention is applied. However, the image forming apparatus is not limited to the printer 10 and may be a copying machine. A facsimile machine may also be used.

  (2) In the above embodiment, the image forming apparatus capable of color printing has been described as an example. However, the present invention is not limited thereto, and the developing device 20 according to the present invention is applied to an image forming apparatus for monochrome printing. Also good.

  (3) In the above embodiment, two baffle plates (the lower baffle plate 51 and the upper baffle plate 54) are provided in the duct portion 50. However, the number may be one, or three or more. There may be.

  (4) In the above embodiment, a filter may be provided at the downstream end of the meandering flow path 262. By doing so, the airflow passing through the meandering flow path 262 reaches the filter in a state where a predetermined amount of toner is removed in the meandering flow path 262, so that the filter is less likely to be clogged by reducing the load. Accordingly, it is possible to reduce the frequency of replacement of the old and new filters within a certain period, and as a result, it is possible to contribute to the reduction in running cost when the filter is employed.

It is explanatory drawing of front sectional view for demonstrating one Embodiment of the internal structure of the printer with which the image development apparatus concerning this invention was applied. 1 is an overall perspective view showing an embodiment of a developing device according to the present invention. FIG. 3 is a cutaway perspective view of a state in which the developing device shown in FIG. 2 is cut at a substantially central portion in the longitudinal direction. It is sectional drawing of the IV-IV line view of FIG. It is a disassembled perspective view which shows one Embodiment of a duct part. It is an assembly drawing of the duct part shown in FIG. 5, (A) is an assembly perspective view, (B) is sectional drawing of the duct part shown to (A).

Explanation of symbols

10 Printer (image forming device)
11 Apparatus Main Body 111 Paper Conveying Path 112 Conveying Roller Pair 113 Second Transfer Roller 114 Discharge Conveying Path 12 Image Forming Unit 12M Magenta Unit 12C Cyan Unit 12Y Yellow Unit 12K Black Unit 121 Photosensitive Drum 122 Charging Device 123 Exposure Device 124 Transfer belt 124a Drive roller 124b Driven roller 125 Transfer roller 126 Cleaning device 13 Fixing unit 131 Heating roller 132 Fixing roller 133 Fixing belt 134 Pressure roller 14 Paper storage unit 141 Manual tray 142 Paper tray 143 Pickup roller 15 Paper discharge unit 151 Output tray 20 Developing device 21 Casing 211 Front wall member 212 Rear wall member 213 Projection 213a Positioning projection 22 Lower casing 221 Arc wall 222 Below Left wall 223 bottom plate 23 the upper casing 231 inclined wall (first wall (wall surface extending in the vertical direction of the casing))
231a Square groove 232 Top plate 233 Upper left wall 234 Toner supply opening 235 Vertical wall (second wall (plate wall))
235a Locking protrusion 25 Partition 251 Connection opening 253 Partition 26 V-shaped groove 261 Flow hole (pressure release hole)
262 Meandering channel 27 Pumping space 29 Gear mechanism 30 Toner stirring mechanism 31 First spiral feeder (stirring conveyance member)
32 Second spiral feeder (stirring conveying member)
40 Toner supply mechanism 41 Developing roller 41a Sleeve 41b Cylindrical magnet body 411 First roller shaft 42 Developing roller 421 Second roller shaft 43 Layer thickness regulating member 44 Positioning roller 50 Duct portion 51 Lower baffle plate 511 Extension portion 52 Cover body 521 Positioning hole 522 Locking plate piece 522a Locking hole 523 Slit 53 Suspension plate 54 Upper baffle plate N1 1st N pole N2 2nd N pole N3 3rd N pole S1 1st S pole S2 2nd S pole S3 3rd S pole S4 4th S pole P paper P1 paper bundle

Claims (7)

A casing for containing toner;
A stirring and conveying member disposed in the casing and configured to convey the toner while stirring;
A pressure relief hole that is drilled at a predetermined location of the casing and allows the pressure in the casing to escape;
A duct portion having a flow path having one end side connected to the pressure release hole and the other end side opened to the outside;
The developing device, wherein the flow path is a flow path meandering from the one end side to the other end side.   The developing device according to claim 1, wherein the duct portion is provided on an upper surface side of the casing. A plurality of the pressure relief holes are formed in the casing,
The developing device according to claim 1, wherein one end side of the duct portion is formed so as to cover all of the plurality of pressure release holes. The duct portion includes a first wall and a second wall that are erected upward from the casing so as to face each other with the pressure release hole interposed therebetween, and a space between the facing surfaces of the first wall and the second wall is between The flow path,
A first plate protrudes from the facing surface of the first wall toward the second wall,
A second plate protrudes from the facing surface of the second wall toward the first wall,
A space is provided between the front ends of the first plate and the second plate and the opposing surface of the other plate, and the height positions at which the first plate and the second plate protrude are different. The developing device according to claim 1, wherein the developing device is an image forming apparatus.   A wall plate is provided at an upper position of the casing so as to form a recess facing the wall surface extending in the vertical direction of the casing, the wall surface is the first wall, and the wall plate is the second wall. The developing device according to claim 4.   The developing device according to claim 1, further comprising a lid that is attached to the other end of the duct portion and includes a plurality of slits. An image carrier for carrying a toner image;
The developing device according to claim 1, wherein toner is supplied toward the surface of the image carrier.
An image forming apparatus comprising:

Images