JP5340037B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent developer from accumulating in a specific area in a developing device, by more effectively preventing floating toner from the inside of the casing of the developing device from leaking out to the outside, as compared with the conventional developing device. <P>SOLUTION: The casing 21 of the developing device 20 incorporates a developing roller 42 and a blade 43 for regulating the quantity of the developer carried by the developing roller 42. The casing 21 has an air introducing portion 50 opposed to the developing roller 42 at a position below the developing roller 42. The air introducing portion 50 is provided with air inflow holes (i.e., an air inlet 518, a long opening 515c, a long hole 523, and an angular hole 524) for taking in air from the outside. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus including an image carrier and a developer carrier.

  An electrophotographic image forming apparatus irradiates a peripheral surface of an image carrier (photosensitive drum) with light based on image information read from an original image or transmitted from an external device such as a computer to form an electrostatic latent image. After forming the toner and supplying toner from the developing device to the electrostatic latent image to form a toner image, the toner image is transferred to a sheet. The paper after the transfer process is subjected to a toner image fixing process and then discharged to the outside.

  By the way, in recent years, in the image forming apparatus, the configuration of the apparatus becomes complicated as color printing and high-speed processing progress, and the toner stirring member in the developing device is forced to rotate at high speed in order to cope with high-speed processing. As a result, the inside of the developing device easily becomes a positive pressure higher than the atmospheric pressure. When the pressure in the developing device becomes positive, when toner from the developing device is supplied to the photosensitive drum, a part of the toner becomes floating toner and is discharged from the toner supply port to the photosensitive drum. The main body of the apparatus is contaminated, and necessary toner is hardly supplied to the electrostatic latent image. As a result, troubles such as a so-called toner drop phenomenon that the toner is not supplied to the portion where the toner is to be laminated on the peripheral surface of the photosensitive drum are likely to occur.

  In order to solve such a problem, Patent Document 1 proposes a developing device improved so as to prevent toner leakage. In this developing device, a casing is internally provided with a stirring roller and a developing roller that is disposed downstream of the stirring roller and supplies toner to the peripheral surface of the photosensitive drum. The stirring member is disposed slightly above the bottom plate of the casing, and the developing roller is disposed obliquely above the stirring member.

  A partition plate (a sink plate in Patent Document 1) that guides the toner to flow toward the peripheral surface of the developing roller is provided obliquely above the stirring member. Due to the presence of the partition plate, the inside of the casing is divided into upper and lower parts, and the toner above the partition plate is supplied to the space below the partition plate through the gap between the lower end edge of the partition plate and the bottom plate of the casing. Is done. The toner supplied here is continuously pumped up to the peripheral surface of the developing roller by the driving rotation of the stirring roller, and is supplied from the peripheral surface of the developing roller to the peripheral surface of the photosensitive drum.

  In such a developing device, the partition plate is provided with a vent hole, and air in a space below the partition plate, which has become positive pressure due to rotation of the stirring roller, is passed through the vent hole to the space above the partition plate. It is possible to extract. As a result, the pressure in the space in which the stirring roller is provided is reduced, so that air containing floating toner is not discharged to the outside from the toner discharge port. As a result, the floating toner from the toner discharge port is prevented. Leakage can be prevented.

Japanese Patent Laid-Open No. 10-48946

  By the way, in the developing device described in Patent Document 1, air containing floating toner existing in the space below the partition plate in the casing passes through the vent hole formed in the partition plate. The flow direction is distributed toward the space above the partition plate, and this flow direction is substantially orthogonal to the conveyance direction of the toner fed to the photosensitive drum by the rotation of the developing roller.

  Therefore, in many cases, the strength of the airflow directed toward the vent hole is not so strong as to cancel the air flow to be accompanied by the rotation of the developing roller. As a result, the air containing floating toner is caused by the rotation of the developing roller. Is liable to flow toward the peripheral surface of the photosensitive drum and leaks from the toner supply opening of the casing facing the peripheral surface.

  The present invention has been made to solve the conventional problems, and a developing device capable of effectively preventing leakage of floating toner from the inside of the casing of the developing device to the outside more than in the past. An object of the present invention is to provide an image forming apparatus provided.

An image forming apparatus according to an aspect of the present invention includes an image carrier on which an electrostatic latent image is formed, a developing roller facing the image carrier, and a magnetic roller that supplies developer to the developing roller. includes a developer carrying member for supplying the developer to the image bearing member, a blade for regulating an amount of developer to be carried on the developer carrying member, and a casing for accommodating the developer carrying member, wherein casing has a wall portion containing the developer carrying member facing the wall surface at the upper position of the blade, the said wall is provided with an air inlet, the air inflow hole, the rotation of the image bearing member An inlet hole that opens toward the upstream side in the direction, and an introduction hole that introduces air into the casing from a position closer to the image carrier than the inlet hole. Facing the peripheral surface, the wall A support member attached to a position directly above the blade; and a plate member mounted on the upper surface side of the support member and provided with the wall surface. The inlet hole is provided in the support member. An image forming apparatus, wherein the image forming apparatus is a long hole extending in an axial direction of the magnetic roller, which is provided in a plate member and directs the air taken in from the inlet hole toward the magnetic roller . (Claim 1).

According to this configuration, the developer to be deposited on the wall surface can be caused to flow by the flow of air flowing into the casing from the air inflow hole provided in the wall portion facing the developer carrier. Thereby, it is possible to prevent the developer from being deposited on the wall surface. In addition, according to this configuration, it is possible to easily send air into the casing through the air inlet as the image carrier rotates. The air that has passed through the air inlet is further introduced into the casing from an introduction hole provided at a position closer to the image carrier than the air inlet, so that air containing floating toner in the vicinity of the image carrier is It is possible to form an air flow that flows in a direction away from the air. Further, according to this configuration, the structure for introducing air into the casing can be simplified, and it can be adapted to various developing devices, and versatility can be improved.

  In the above configuration, it is preferable that the air inflow hole is provided at a position close to the image carrier.

  According to this configuration, an air flow is easily formed in the casing of the developing device from a position close to the image carrier to the side opposite to the image carrier. For this reason, it is possible to prevent the developer from being accumulated while the air containing the floating toner in the casing is prevented from leaking out from the opposed opening of the image carrier.

  According to the image forming apparatus of the present invention, it is possible to suppress a toner dropping phenomenon or the like caused by the accumulated developer accumulated in the casing of the developing device.

1 is an explanatory diagram of a front sectional view for explaining an embodiment of an internal structure of an image forming apparatus according to the present invention. It is the perspective view seen from the front right surface side which shows one Embodiment of the developing device to which the air introduction part of 1st Embodiment which concerns on this invention was applied. It is the III-III sectional view taken on the line of FIG. It is a disassembled perspective view which shows the air introduction part of 1st Embodiment. FIG. 5 is a partially cut-out assembly perspective view of the air introduction section shown in FIG. 4. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5. It is explanatory drawing of front sectional view for demonstrating the effect | action of an air introduction part. It is a disassembled perspective view which shows the air introduction part which concerns on 2nd Embodiment. FIG. 9 is a partially cut-out assembly perspective view of the air introduction section shown in FIG. 8. FIG. 10 is a sectional view taken along line XX in FIG. 9.

  FIG. 1 is a front cross-sectional view illustrating an embodiment of the internal structure of the image forming apparatus according to the present invention. In the present embodiment, the image forming apparatus 10 is exemplified by a printer that performs image forming processing based on image information transmitted from an external device such as a computer. As shown in FIG. 1, an image forming apparatus 10 is formed by an image forming section 12 that performs image forming processing based on image information from an external device in a box-shaped apparatus main body 11 and the image forming section 12. A fixing unit 13 for fixing the image transferred to the paper P and a paper storage unit 14 for storing the transfer paper are provided, and the paper P after the fixing process is provided above the apparatus main body 11. Is formed by forming a paper discharge portion 15 from which the paper is discharged.

  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 and various keys for inputting output conditions.

  The image forming unit 12 forms a color image on the paper P fed from the paper storage unit 14 by a predetermined image forming process. In the present embodiment, a magenta unit 12M that uses a magenta developer and a cyan unit that uses a cyan developer are sequentially arranged from the upstream side (the right side of the paper surface 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 unit 12M, 12C, 12Y, 12K is provided with a photosensitive drum (image carrier) 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 toner from the corresponding developing device 20 while rotating counterclockwise in FIG. Each developing device 20 is supplied 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 system 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 to charge 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.

  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. The peripheral surface of the body drum 121 is irradiated. Thereby, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 121. By supplying only the toner in 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 by a driving roller 124 a while being synchronized with each photoconductive drum 121 while being pressed against the peripheral surface of the photoconductive drum 121 by a transfer roller 125 provided corresponding to each photoconductive drum 121. It circulates between the rollers 124b.

  As the transfer belt 124 circulates, 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 on 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 the overcoating state.

  As a result, 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.

  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. The sheet conveying path 111 is provided with a pair of conveying rollers 112 at appropriate positions, and the sheet from the sheet storage unit 14 is conveyed toward the transfer belt 124 that is wound around the driving roller 124 a by the driving of the conveying roller pair 112. Is done. 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. The fixing unit 13 includes a heating roller 131 having an energization heating element as a heating source therein, a fixing roller 132 disposed opposite to the heating roller 131 on the left side in FIG. 1, the fixing roller 132 and the heating roller. A fixing belt 133 stretched between the rollers 131 and a pressure roller 134 disposed to face the fixing roller 132 with the fixing belt 133 interposed therebetween.

  When the paper P supplied to the fixing unit 13 passes through the nip portion between the transfer belt 124 and the second transfer roller 113, the toner P is subjected to fixing processing by obtaining heat from the fixing belt 133. The

  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. A sheet bundle P1 in which a plurality of sheets P are stacked 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 right wall surface of the apparatus main body 11, but manually fed. Only when this is done, as shown in FIG. 1, it is pulled out from the wall surface and used for manual paper feeding.

  The uppermost sheet P of the sheet bundle P1 stored in the sheet tray 142 is fed from the sheet bundle P1 toward the sheet conveyance path 111 by driving the pickup roller 143 from the upper end of the downstream end (left end in FIG. 1). The paper P fed out one by one is fed toward the nip portion between the second transfer roller 113 and the transfer belt 124 in the image forming unit 12 through the paper transport path 111 by driving the transport roller pair 112.

  FIG. 2 is a perspective view seen from the front right side showing one embodiment of the developing device to which the air introduction unit of the first embodiment according to the present invention is applied, and FIG. 3 is a line III-III in FIG. It is sectional drawing. 2 and 3, the XX direction is referred to as the left-right direction, and the Y-Y 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 forward, and the + Y direction is forwarded. It is called the back.

  As shown in FIGS. 2 and 3, the developing device 20 includes a developer stirring mechanism 30 that stirs the developer in a casing 21 that is long in the front-rear direction, and a development that is stirred by the developer stirring mechanism 30. A developer supplying mechanism 40 that supplies the developer toward the peripheral surface of the photosensitive drum 121 and an air flow that causes the developer to accumulate at a predetermined blind spot position to be described later in the casing 21 by appropriately introducing air from the outside. And an air introduction part 50 for taking in air from the outside (outside of the developing device 20). Incidentally, in the present embodiment, the air introduction part 50 is positioned as a part of the casing 21.

  As shown in FIG. 2, the casing 21 includes a lower housing 22 to which the developer stirring mechanism 30 is mounted, and an upper portion to which the developer supply mechanism 40 connected to the upper portion of the lower housing 22 is mounted. A two-stage structure including a housing 23 is formed. A gear mechanism housing portion 24 for housing a gear mechanism that transmits a driving force from a driving motor (not shown) to the developer stirring mechanism 30 and the developer supply mechanism 40 is formed at the rear end portion of the casing 21. Has been.

  The lower housing 22 has a front end projecting slightly forward from the front end of the upper housing 23, and accepts toner from a toner cartridge (not shown) on the upper surface of the front projecting portion. An opening 221 is provided, and an opening / closing lid 222 that closes the toner receiving opening 221 so as to be openable and closable is provided.

  Before the toner cartridge is mounted on the apparatus main body 11, the opening / closing lid 222 is rotated around a predetermined axis and closed as indicated by an arrow in FIG. 2. The opening / closing lid 222 is opened by pressing a predetermined operation lever when the toner cartridge is mounted on the apparatus main body 11, whereby toner from the toner cartridge enters the lower housing 22 through the toner receiving opening 221. Supplied.

  Further, the upper housing 23 is provided with a toner supply opening (opposing opening) 231 facing the peripheral surface of the photosensitive drum 121, which is formed on the left wall surface in a longitudinal direction with a predetermined vertical dimension. ing. Then, only the toner in the developer pumped into the upper housing 23 is supplied toward the peripheral surface of the photosensitive drum 121 (FIG. 3) through the toner supply opening 231. The remaining toner and carrier that are not supplied to the photosensitive drum 121 are returned to the lower housing 22.

  As shown in FIGS. 2 and 3, the toner stirring mechanism 30 includes a first spiral feeder 31 extending in the front-rear direction at a right position in the lower housing 22, and a left side of the first spiral feeder 31 in the lower housing 22. And a second spiral feeder 32 disposed in parallel via a partition wall 25 (FIG. 3). The toner supplied into the lower housing 22 through the toner receiving opening 221 (FIG. 2) is conveyed toward the rear (back side of the paper surface of FIG. 3) by the driving rotation of the first spiral feeder 31 together with the existing carrier. The

  On the other hand, the partition wall 25 is provided with communication openings 251 at the rear end and the front end, respectively. Incidentally, in FIG. 3, the communication opening 251 at the rear end is shown by a dotted line. The developer conveyed by driving the first spiral feeder 31 toward the rear in the right side space of the partition wall 25 in the lower housing 22 is carried into the left space of the partition wall 25 through the rear connection opening 251. In this case, a part of the pumping space 26 is formed between the left side of the partition wall 25 of the lower housing 22 and the upper housing 23 while being transported forward by the driving of the second spiral feeder 32 and is long in the front-rear direction. Pumped through (FIG. 3) toward the upper housing 23 above. On the other hand, the remaining developer that has not been pumped is returned to the space on the right side of the partition wall 25 through the front communication opening 251 and circulated and conveyed.

  The developer supply mechanism 40 is for supplying only the toner in the developer pumped from the lower housing 22 into the upper housing 23 by driving the developer agitating mechanism 30 to the photosensitive drum 121. The developer supply mechanism 40 includes a magnetic roller 41 extending in the front-rear direction disposed on the right side of the upper housing 23 so as to face the second spiral feeder 32, and an obliquely upper left position of the magnetic roller 41 in the upper housing 23. A developing roller (developer carrying member) 42 that is arranged in parallel with the magnetic roller 41 so that the peripheral surfaces thereof face each other with a slight gap, and a lower left peripheral surface of the magnetic roller 41 having a leading edge. And a blade 43 that regulates the amount of developer stacked on the peripheral surface of the magnetic roller 41 to a predetermined value. In order to set the amount of developer stacked on the peripheral surface of the magnetic roller 41 to a predetermined value, the gap formed between the tip edge of the blade 43 and the peripheral surface of the magnetic roller 41 is the most suitable depending on the situation. Set to a suitable value.

  The magnetic roller 41 is supported so as to be concentric and relatively rotatable around a magnetic roller shaft 411 passing through the front and rear walls of the upper housing 23. On the other hand, the developing roller 42 is supported so as to be concentrically rotatable around the developing roller shaft 421.

  The magnetic roller 41 rotates relative to the magnetic roller shaft 411 in the clockwise direction when the driving force of the driving motor (not shown) is transmitted via the gear mechanism (not shown) in the gear mechanism housing 24. At the same time, the developing roller 42 is driven by the rotation of the magnetic roller 41 via the gear mechanism (not shown), and rotates around the developing roller shaft 421 in the clockwise direction.

  The magnetic roller 41 includes a cylindrical sleeve 412 made of nonmagnetic material such as aluminum, and a columnar magnet portion 413 on which the sleeve 412 is fitted. The cylindrical magnet portion 413 does not rotate integrally with the magnetic roller shaft 411 (that is, is fixed), whereas the sleeve 412 rotates clockwise around the cylindrical magnet portion 413 around the axis of the magnetic roller shaft 411. Can be rotated toward.

  The columnar magnet portion 413 is provided with a plurality of permanent magnets whose magnetic pole positions are set appropriately in order to pump up the developer effectively in cooperation with the rotation of the sleeve 412 and the magnetic action. As the sleeve 412 rotates, the developer in the lower housing 22 is appropriately pumped into the upper housing 23, and the developer is properly supplied from the peripheral surface of the sleeve 412 to the peripheral surface of the developing roller 42. Done.

  The blade 43 has an elongated rectangular shape in plan view, and the length dimension in the front-rear direction is set to be substantially the same as the length dimension of the magnetic roller 41. The blade 43 is fixed to the upper surface side of the blade support plate 212 that protrudes from the upper edge portion of the left wall (opposing wall) 211 of the casing 21 toward the peripheral surface of the magnetic roller 41 so as to incline upward. Yes.

  Therefore, the developer drawn up from the pumping space 26 in the casing 21 by the rotation of the magnetic roller 41 around the magnetic roller shaft 411 in the clockwise direction and stacked on the sleeve 412 of the magnetic roller 41 is transferred to the tip of the blade 43 and the sleeve 412. A predetermined amount of developer is set by passing through the gap between the developer and the peripheral surface, and the developer of the set amount is rotated to the peripheral surface of the developing roller 42 that rotates clockwise around the developing roller shaft 421. Migrated.

  Further, in the present embodiment, the inertia dust collector 27 that exhausts the air in the casing 21 to the outside at a position directly above the magnetic roller 41 in the upper housing 23 and collects the floating toner in the air at this time. Is provided. The inertia dust collector 27 discharges air in the casing 21 that has become positive pressure due to the drive rotation of the second spiral feeder 32 and the magnetic roller 41 to the outside, and collects floating toner contained in the discharged air. Is for.

  Such an inertia dust collector 27 includes a dust collection box 271 having a long box shape in the front-rear direction (a direction orthogonal to the paper surface of FIG. 3), and a plurality of dust collection boxes 271 disposed in the dust collection box 271. Baffle plate 276. The dust collection box 271 includes a bottom plate 272 that is slightly shorter than the longitudinal dimension of the upper housing 23, a pair of side plates 273 that are erected from the left and right edges of the bottom plate 272, and a pair of side plates 273. And a pair of front and rear end plates 275 for closing the front and rear end surfaces of the elongated rectangular tube formed by the bottom plate 272, the pair of side plates 273, and the top plate 274. Yes.

  On the other hand, a pair of left and right dust collector mounting walls 232 extending in the front-rear direction are provided upright at a position directly above the magnetic roller 41 in the upper housing 23. The inner dimension of the pair of dust collector mounting walls 232 in the left-right direction is set slightly larger than the outer dimension between the pair of side plates 273 of the dust collection box 271. Therefore, the dust collection box 271 can be mounted between the pair of dust collector mounting walls 232.

  The bottom plate 272 is provided with an air inlet 272a, and the top plate 274 is provided with an air outlet 274a. The upper housing 23 is provided with an air circulation hole 233 at a position between the pair of dust collector mounting walls 232. Accordingly, the air in the casing 21 that has become positive pressure due to the outside air introduced through the air introduction unit 50 by driving the developer agitating mechanism 30 and the magnetic roller 41 etc. is the air circulation hole 233 and the air inlet 272a. Is introduced into the dust collection box 271, is subjected to inertial dust collection by collision with the baffle plate 276, and then is discharged to the outside through the air outlet 274 a.

  Each of the baffle plates 276 is provided so as to protrude alternately from the opposed surfaces of the pair of side plates 273 toward each other, thereby forming a zigzag air flow passage in a front view. . Accordingly, the air introduced into the dust collection box 271 changes its direction by 180 ° a plurality of times through the zigzag flow path, and the floating toner is removed by inertia at the time of this direction change. It is effectively prevented from being discharged to the outside.

  In this embodiment, as shown in FIG. 7, the dimension of the gap d1 between the tip of the blade 43 and the peripheral surface of the magnetic roller 41 is set to 0.37 ± 0.04 mm. The dimension of the gap d2 between the circumferential surface and the circumferential surface of the developing roller 42 is set to 0.28 ± 0.05 mm, and the gap d3 between the circumferential surface of the developing roller 42 and the circumferential surface of the photosensitive drum 121 is set. The dimension is set to 0.12 ± 0.05 mm. However, the dimensions of the gaps d1, d2, and d3 are not limited to the above values, and optimum values are set according to the model of the developing device 20, operating conditions, and the like.

  Hereinafter, based on FIGS. 4-6, the air introduction part 50 is demonstrated, referring also to other drawings as needed. 4 and 5 are perspective views showing an embodiment of the air introduction unit 50, FIG. 4 is an exploded perspective view, and FIG. 5 is a partially cut-out assembled perspective view. 6 is a cross-sectional view taken along line VI-VI in FIG. 4 to 6 are the same as those shown in FIG. 2 (-X: leftward, + X: rightward, -Y: forward, + Y: backward).

  First, as shown in FIG. 4, the air introduction unit 50 is supported by the support frame 51 fixed to the position of the lower edge portion of the toner supply opening 231 in the left wall 211 of the casing 21. And a sealing film 53 attached to the plate member 52.

  The support frame 51 has a lateral V shape with a sharp rearward view as viewed from the -Y direction. The support frame body 51 is lowered downward toward the front, which is constructed between a pair of left and right V-shaped side plates 511 each including a lower arm 512 and an upper arm 513 and between the lower arms 512 of the pair of V-shaped side plates 511. The lower inclined plate 514 and the upper inclined plate 515 that is installed between the upper arms 513 and rises forward.

  The lower inclined plate 514 is installed between the upper edges of the pair of lower arms 512, while the upper inclined plate 515 is installed between the lower edges of the pair of upper arms 513. Between the lower inclined plate 514 and the upper inclined plate 515, a plurality of reinforcing plates 516 are provided at equal pitches in the left-right direction. The presence of these reinforcing plates 516 makes the support frame body 51 strong in strength. It is a thing.

  Further, between the reinforcing plates 516 adjacent to each other, a leakage preventing plate 519 standing from the left end portion of the lower inclined plate 514 is installed. The leakage prevention plate 519 is for preventing the developer deposited on the lower inclined plate 514 from leaking to the outside. Therefore, even if the toner stays and accumulates on the lower inclined plate 514 due to the airflow, it is effectively prevented that the accumulated toner slides on the lower inclined plate 514 and is scattered outside. be able to.

  Between the reinforcing plates 516, air inlet holes (air inflow holes) 518 are formed, respectively, and external air from these air inlet holes 518 passes through the air introduction part 50 (specifically, to the upper inclined plate 515). (Via the long openings 515 c provided and the long holes 523 and square holes 524 described below provided in the plate member 52) into the space surrounded by the magnetic roller 41, the developing roller 42 and the photosensitive drum 121 in the casing 21. be introduced. As shown in FIG. 3, the air inlet 518 is opened toward the upstream side in the rotation direction of the photosensitive drum 121 (below the photosensitive drum 121 in the example shown in FIG. 3).

  In particular, the upper inclined plate 515 includes a high gradient inclined plate 515a having the same inclination angle as the upper edge of the upper arm 513 protruding forward from the rear end position of the upper arm 513, and the high gradient inclined plate 515a. And a low-gradient inclined plate 515b having a gentler inclination angle than the high-gradient inclined plate 515a extending from the front edge portion to a position slightly beyond the front end of the upper arm 513.

  The low-gradient inclined plate 515b is provided with a long opening 515c extending substantially over the entire length in the left-right direction, and at the left and right ends on the rear end side, a screw with a top opening extending in the up-down direction. Screw seats 515d provided with holes 515e are provided.

  Further, at the front end portion of each lower arm 512, a mounted portion 517 that protrudes in opposite directions is provided. These mounted portions 517 are for mounting the air introduction portion 50 to the casing 21 (FIG. 2). Incidentally, the actual mounted portion 517 has a complicated shape in accordance with the local condition of the casing 21, but is simplified in FIG.

  The plate member 52 is supported by the upper arm 513 of each V-shaped side plate 511 in the support frame 51. The plate member 52 includes a plate main body (a part of a wall surface facing the developer carrying member) 521 that is installed between the upper edge portions of the pair of V-shaped side plates 511 and a front edge portion of the plate main body 521. And a hanging plate 522 along the front edge portion of the upper arm 513 of the V-shaped side plate 511.

A plurality of long holes ( introduction holes (air inflow holes)) 523 extending in the left-right direction at equal pitches are formed in the vicinity of the front edge of the lower arm 512, and adjacent long holes 523 are provided. Square holes ( introduction holes (air inflow holes)) 524 are respectively formed at positions slightly rearward. The long holes 523 and the square holes 524 ensure a necessary strength of the plate body 521 and provide an air inflow hole over the entire length of the plate body 521.

  The long hole 523 and the square hole 524 are preferably provided as close to the photosensitive drum 121 as possible. By doing so, the air introduced into the casing 21 from the long hole 523 and the square hole 524 is attracted by the rotation of the magnetic roller 41 and flows in the direction of the magnetic roller 41. It is possible to prevent the floating toner T2 (FIG. 7) that is floating from leaking from the toner supply opening 231.

  The plate main body 521 has through holes 525 at positions corresponding to the screw holes 515e of the pair of screw seats 515d provided on the low gradient inclined plate 515b of the support frame 51. Then, in a state where the plate body 521 is installed between the pair of upper arms 513, the screws B are inserted into the respective through holes 525, and subsequently screwed into the respective screw holes 515e to be fastened. As shown in FIG. The sealing film 53 has a casing 21 having an air introduction portion 50 mounted on the apparatus main body 11 of the image forming apparatus 10, and an upper edge portion of the sealing film 53 is arranged around the photosensitive drum 121 as shown in FIG. It is in contact with the surface.

  The sealing film 53 is set to have the left and right length dimensions substantially the same as the length dimension of the plate member 52, and the upper and lower width dimensions are such that the upper edge reaches the peripheral surface of the photosensitive drum 121. Set to the dimension you get.

  On the other hand, a double-sided tape 526 is applied to the outer surface (right surface) side of the hanging plate 522 of the plate member 52. Therefore, by sticking the lower half of the sealing film 53 to the double-sided tape 526, the sealing film 53 is attached to the left end position of the air introduction part 50 as shown in FIG.

  By employing such a sealing film 53, leakage of toner from the lower portion of the toner supply opening 231 of the casing 21 can be effectively prevented. In addition, the air flow accompanying the rotation of the photosensitive drum 121 can be easily taken from the air inlet hole 518 and is accumulated on the plate main body 521 by the air flow toward the magnetic roller 41 introduced through the long hole 523. There is no.

  Hereinafter, the operation of the air introduction unit 50 will be described with reference to FIG. 7 and other drawings as necessary. FIG. 7 is an explanatory diagram of a front cross-sectional view for explaining the operation of the air introduction unit 50. In FIG. 7, each member is schematically shown in a simplified manner. Further, the direction display by X in FIG. 7 is the same as that in FIG. 2 (−X: leftward, + X: rightward).

  First, when the magnetic roller 41 rotates clockwise around the roller center as indicated by an arrow in FIG. 7, the developer T in the scooping space 26 is removed from the cylindrical magnet portion provided in the magnetic roller 41. The magnetic force of 413 (FIG. 3) attracts the outer peripheral surface of the magnetic roller 41 (specifically, the outer peripheral surface of the sleeve 412 (FIG. 3) externally fitted to the cylindrical magnet portion 413) and reaches the blade 43 in a layered manner. .

  Then, when the developer T passes through the gap d1 between the tip of the blade 43 and the peripheral surface of the magnetic roller 41, the portion exceeding the gap d1 is scraped off by the blade 43 to a predetermined layer thickness. Thus, it goes to the circumferential surface of the developing roller 42.

  When the developer T reaches the gap d <b> 2 between the peripheral surface of the magnetic roller 41 and the peripheral surface of the developing roller 42, the developing of the peripheral surface of the magnetic roller 41 is now performed by the magnetic force of the magnet built in the developing roller 42. The agent T is transferred to the peripheral surface of the developing roller 42 that is rotating clockwise around the roller center.

  Next, the developer T transferred to the peripheral surface of the developing roller 42 is rotated around the drum center from the bottom by the clockwise rotation of the developing roller 42, and the peripheral surface of the photosensitive drum 121. Then, only the toner T1 in the developer T moves toward the portion where the electrostatic latent image is formed on the peripheral surface of the photosensitive drum 121. As a result, a toner image along the electrostatic latent image is formed on the peripheral surface of the photosensitive drum 121.

  By the way, when the developer T is transferred from the magnetic roller 41 to the developing roller 42 and when the toner T1 in the developer T is transferred from the developing roller 42 to the photosensitive drum 121, or the developing roller 42 and the magnetic roller. By the conveyance by the rotation of 41, the magnetic roller 41, the developing roller 42, the photosensitive drum 121, and the plate body 521 may jump out into the surrounding space S and float. The floating toner T2 formed in this way is in a state of drifting in the air in the surrounding space S.

  On the other hand, in the surrounding space S, as shown in FIG. 7, an air flow A that is accompanied by the clockwise rotation of the magnetic roller 41 is formed, and along with the clockwise rotation of the developing roller 42. An air flow B is formed. Accordingly, since the developer is slightly accumulated in the gap d2 between the magnetic and developing roller 41 and 42 facing each other, this becomes a resistance and almost no air flow is generated between the magnetic and developing roller 41 and 42. Not formed.

  As a result, in the surrounding space S, the airflow A, B causes a mountain-shaped airflow C in which a portion corresponding to the gap d2 of the magnetic roller 41 opposite to the magnetism and the developing rollers 41, 42 is convex upward. Will be formed.

  Further, since the developer is accumulated on the lower surface side (pumping space 26 side) of the blade 43, the gap 43 between the tip of the blade 43 and the peripheral surface of the magnetic roller 41 is directed to the surrounding space S. There is almost no airflow. Then, the upstream side of the air flow A becomes negative pressure. Since the air flow A → air flow C → air flow B and air flow in the surrounding space S by the rotation of the magnetism and the developing rollers 41 and 42, the air flows from the long holes 523 and the square holes 524 of the plate body 521 into the surrounding space S. The air flow indicated by the dotted arrow introduced in FIG. 5 flows toward the upstream side of the negative air flow A, that is, toward the tip side of the blade 43.

  Accordingly, when air is not introduced into the surrounding space S through the long hole 523 and the square hole 524, the toner mass accumulated on the upper surface of the plate body 521 slides down on the plate body 521 due to vibration or the like, and the blade 43 When stopped by the leading end, the toner lump is conveyed together with the developer on the peripheral surface of the magnetic roller 41, and the toner lump is developed on the photosensitive drum 121, thereby forming a toner drop image or the toner lump. However, in this embodiment, it is introduced into the surrounding space S from the long hole 523 and the square hole 524. Since the air flow indicated by the dotted arrow in FIG. 7 reaches the upstream side of the air flow A, it is possible to effectively prevent the floating toner T2 from being deposited on the upper surface of the plate body 521. It can be.

  8 and 9 are perspective views showing an air introduction part 50 ′ according to the second embodiment, FIG. 8 is an exploded perspective view, and FIG. 9 is a partially cut-out assembled perspective view. FIG. 10 is a sectional view taken along line XX of FIG. In addition, the direction display by X and Y in FIGS. 8-10 is the same as the case of FIG. 2 (-X: leftward, + X: rightward, -Y: front, + Y: back).

  The air introduction part 50 ′ of the second embodiment is arranged in the front-rear direction in which each of the first embodiment is adjacently provided between the reinforcing plates 516 on the inlet side of the inlet hole 518 formed on the left surface of the support frame 51. Instead of the plurality of short leakage prevention plates 519, a long end air flow restriction plate 54 having a front-rear length substantially the same as the front-rear length of the support frame 51 is employed. The other configuration of the air introduction unit 50 ′ of the second embodiment is the same as that of the air introduction unit 50 of the first embodiment.

  The end air flow restricting plate 54 seals the front and rear ends of the plurality of air inlet holes 518 in the support frame body 51 over a predetermined range, thereby passing the air inlet holes 518 through the support frame body. This is to prevent the airflow introduced into 51 in the support frame 51 and the surrounding space S (FIG. 7) from being biased toward the front and rear ends, and is formed by a thin plate made of hard synthetic resin. Has been.

  The end airflow restriction plate 54 has a front-rear length that is substantially the same as the inner dimension between the pair of front and rear lower arms 512 of the support frame 51, and a vertical dimension that can cover the substantially lower half of the inlet hole 518. The restriction plate main body 541 is sized as described above, and a pair of front and rear end closing pieces 542 projecting upward from the upper edge portions of both ends of the restriction plate main body 541.

  In the present embodiment, each end closing piece 542 has a length dimension (front-rear dimension) set to 1/10 to 1/9 of the front-rear dimension of the restriction plate body 541, and the vertical dimension is The dimension is set such that the inlet hole 518 can be reliably closed.

  On the other hand, a left surface installation plate 512 a provided between the pair of lower arms 512 is provided at the lower left portion of the support frame 51. Double-sided tape 543 is attached to the left surface construction plate 512a on the outer surface (left surface) side. Therefore, in order to attach the end air flow restriction plate 54 to the support frame 51, the restriction plate main body 541 may be pressed against the double-sided tape 543. By doing so, the end airflow restriction plate 54 can be easily and quickly attached to the support frame 51.

  According to the air introduction part 50 ′ of the second embodiment, the air sucked into the developing device 20 through the air inlet hole 518 is introduced to both ends in the front-rear direction by the pair of end closing pieces 542 of the end air flow restriction plate 54. You can regulate heading. Therefore, it is possible to effectively prevent the developer from being biased to both ends in the developing device 20 that do not contribute so much to form a toner image. As a result, the airflow of the sucked air is intensively supplied toward the central portion in the front-rear direction of the plate main body 521 where the toner easily collects, so that the toner can be more effectively deposited on the plate main body 521. Can be prevented.

  As described above in detail, the image forming apparatus 10 according to the present exemplary embodiment has a photosensitive drum 121 on which an electrostatic latent image is formed on the peripheral surface, and supplies the developer to the photosensitive drum 121 to electrostatically. And at least a developing device 20 that forms a toner image along the latent image.

  The casing 21 of the developing device 20 includes a developing roller 42 and a blade 43 that regulates the amount of developer carried on the developing roller 42. The casing 21 has air introducing portions 50 and 50 'facing the developing roller 42 at a position below the developing roller 42. The air introducing portions 50 and 50' have air inflow holes (for introducing air from outside). Specifically, an air inlet hole 518, a long opening 515c, a long hole 523, and a square hole 524) are provided.

  According to such a configuration, the development to be deposited on the plate body (wall surface) 521 of the plate member 52 that is a component of the air introduction portions 50 and 50 ′ by the flow of air flowing into the casing 21 from the air inflow hole. Since the developer can be moved and moved, the developer can be prevented from being deposited on the plate body 521 in advance. As a result, it is possible to prevent the developer from staying, accumulating and solidifying in the casing 21 of the developing device, thereby improving the recoverability of the developer by the developing roller 42 and effectively suppressing the toner dropping phenomenon. can do.

  In this embodiment, since the air inflow hole is provided at a position close to the photoconductive drum 121, the photoconductive drum 121 is located in the casing 21 of the developing device from a position close to the photoconductive drum 121. The air flow can be formed toward the opposite side. As a result, the air containing the floating toner T2 (FIG. 7) in the casing 21 can be prevented from leaking to the outside from the toner supply opening 231 of the developing device 20, and the developer can be prevented from accumulating on the plate body 521. it can.

  In the present embodiment, the air inflow hole provided in the air introduction unit 50 is, as described above, the inlet hole 518 that opens toward the upstream side in the rotation direction of the photosensitive drum 121, and the photosensitive member from the inlet hole 518. A long opening 515c for introducing air into the casing 21 from a position close to the drum 121, and a long hole 523 and a square hole 524 provided in the plate main body 521 are employed.

  According to such a configuration, it is possible to easily send air that moves along with the rotation of the photosensitive drum 121 into the casing 21 from the inlet hole 518. The air that has passed through the inlet hole 518 is further introduced into the casing 21 from an introduction hole provided at a position closer to the photosensitive drum 121 than the inlet hole 518, so that the floating toner T 2 in the vicinity of the photosensitive drum 121 is removed. It is possible to form an air flow in which the contained air flows in a direction away from the photosensitive drum 121.

  In the air introducing unit 50 of the first embodiment provided in the developing device 20, the leakage preventing plate 519 standing from the lower inclined plate 514 is provided in the lower half portion of the air inlet 518. In addition, it is possible to effectively prevent the developer accumulated on the lower inclined plate 514 from sliding down and scattering to the outside of the developing device 20.

  Further, in the air introducing portion 50 ′ of the second embodiment provided in the developing device 20, the long end air flow restriction plates 54 provided with end closing pieces 542 at both ends are provided with the support frame 51. Therefore, the air flow sucked into the developing device 20 is prevented from flowing to both ends in the surrounding space S (FIG. 7), thereby preventing the central portion on the plate body 521. Therefore, it is possible to effectively prevent toner from being easily accumulated in the toner.

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

  (1) In the above embodiment, the printer is described as an example of the image forming apparatus 10. However, the image forming apparatus 10 is not limited to being a printer, and may be a copying machine. A facsimile machine may also be used.

  (2) In the above embodiment, the image forming apparatus 10 is described as an example for color printing. However, the image forming apparatus 10 is not limited to being for color printing. It may be for monochrome printing.

  (3) In the above embodiment, the photosensitive drum 121 has been described as an example of the image bearing member. However, a so-called photosensitive member is provided so as to be rotatable between a pair of rollers instead of the photosensitive drum 121. A belt may be employed.

  (4) In the above embodiment, in order to introduce outside air into the surrounding space S of the casing 21 of the developing device 20, the air introduction part 50 is provided in the casing 21, and air is supplied to the plate member 52 of the air introduction part 50. Although the long hole 523 and the square hole 524 are provided as inflow holes, instead of adopting the air introduction part 50 instead of this, an appropriate place of the casing 21 (specifically, in the above embodiment, the air introduction part 50 is provided). In this case, an air inflow hole may be provided in the left wall 211) in a state where the upper edge portion extends to the vicinity of the peripheral surface of the photosensitive drum 121.

  (5) In the above embodiment, the blade 43 may be moved forward and backward in vibration toward the magnetic roller 41 integrally with the lower inclined plate 514. In order to realize such a configuration, the peripheral surface of the eccentric cam is brought into contact with the end of the blade 43 in the left-right direction and does not interfere with the magnetic roller 41, and the eccentric cam is eccentric by driving a predetermined drive motor. What is necessary is just to make it rotate. By doing so, the plate main body 521 can also be vibrated via the lower inclined plate 514, so that toner accumulation on the plate main body 521 can be more effectively suppressed.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Apparatus main body 111 Paper conveyance path 112 Conveyance roller pair 113 2nd transfer roller 114 Paper discharge conveyance path 12 Image forming part 12M Magenta unit 12C Cyan unit 12Y Yellow unit 12K Black unit 121 Photosensitive drum ( Image carrier)
122 charging device 123 exposure device 124 transfer belt 124a driving 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 feed tray 142 paper tray 143 pickup roller DESCRIPTION OF SYMBOLS 15 Paper discharge part 151 Paper discharge tray 20 Developing apparatus 21 Casing 211 Left wall (opposite wall) 212 Blade support plate 22 Lower housing 221 Toner receiving opening 222 Opening / closing lid 23 Upper housing 231 Toner supply opening (opposing opening)
232 Dust collector mounting wall 233 Air circulation hole 24 Gear mechanism housing portion 25 Bulkhead 251 Communication opening 26 Pumping space 27 Inert dust collector 271 Dust collection box 272 Bottom plate 272a Air inlet 273 Side plate 274 Top plate 274a Air outlet 275 End face plate 276 baffle plate 30 developer stirring mechanism 31 first spiral feeder 32 second spiral feeder 40 developer supply mechanism 41 magnetic roller 411 magnetic roller shaft 412 sleeve 413 cylindrical magnet portion 42 developing roller 421 developing roller shaft 43 blades 50, 50 ′ Air introduction part 51 Support frame body 511 V-shaped side plate 512 Lower arm 512a Left side installation plate 513 Upper arm 514 Lower inclined plate 515 Upper inclined plate 515a High gradient inclined plate 515b Low gradient inclined plate 515c Long opening 515d Screw seat 515e Screw hole 516 Reinforcing plate 517 Mounted portion 518 Inlet hole (air inflow hole) 519 Leak prevention plate 52 Plate member 521 Plate body (part of wall surface facing developer carrier)
522 Drooping plate 523 Long hole (Introduction hole (air inflow hole))
524 square hole (introduction hole (air inflow hole))
525 Through-hole 526 Double-sided tape 53 Sealing film 54 End airflow restriction plate 541 Restriction plate body 542 End closing piece 543 Double-sided tape P Paper P1 Paper bundle S Surrounding space T Developer T1 Toner T2 Floating toner d1 Blade tip and magnetic Gap between the circumferential surface of the roller d2 Gap between the circumferential surface of the magnetic roller and the circumferential surface of the developing roller d3 Gap between the circumferential surface of the magnetic roller and the circumferential surface of the photosensitive drum

Claims (2)

An image carrier on which an electrostatic latent image is formed;
A developer roller facing the image carrier, and a magnetic roller for supplying developer to the developer roller, and a developer carrier for supplying developer to the image carrier;
A blade for regulating the amount of developer carried on the developer carrying body;
A casing for accommodating the developer carrier,
The casing has a wall portion containing the developer carrying member facing the wall surface at the upper position of the blade, the said wall is provided with an air inflow hole,
The air inlet hole is
An air inlet opening toward the upstream side in the rotational direction of the image carrier;
An introduction hole for introducing air into the casing from a position closer to the image carrier than the inlet hole,
The tip of the blade faces the peripheral surface of the magnetic roller,
The wall portion includes a support member attached to a position immediately above the blade, and a plate member that is mounted on the upper surface side of the support member and includes the wall surface.
The inlet hole is provided in the support member,
The image forming apparatus , wherein the introduction hole is a long hole provided in the plate member and extending in the axial direction of the magnetic roller for directing the air taken in from the inlet hole toward the magnetic roller. . The image forming apparatus according to claim 1, wherein the air inflow hole is provided at a position close to the image carrier.

Images