JP4364656B2 - Development device - Google Patents

Description

  The present invention relates to an image forming apparatus, a facsimile apparatus, and a developing device applied to an image forming apparatus such as various printers.

  Conventionally, a developing device for an image forming apparatus as described in Patent Document 1 is known. This developing device supplies toner to the circumferential surface of the photosensitive drum to form a toner image, and a developing roller mounted in the developing device main body so that the circumferential surface faces the circumferential surface of the photosensitive drum And a first agitating and conveying means disposed above the developing roller for conveying the developer in the longitudinal direction, and a second agitating and conveying means for conveying the developer in the opposite direction to the first agitating and conveying means. The developer is partly supplied to the photosensitive drum while being circulated and conveyed between the first and second stirring and conveying means.

  The first and second agitating / conveying units generally employ so-called screw feeders that rotate integrally around a rotation axis. However, the one disclosed in Patent Document 1 is not supported by a developing roller. A mode of following rotation is disclosed. Specifically, a coiled member made of a magnetic material is employed as the first agitating and conveying means, and this coiled member is magnetized by the magnetic force of a permanent magnet embedded in the developing roller, so that the surface of the developing roller is always on. It is in a contact state.

Therefore, when the developing roller is driven and rotated about the axis, the coiled member is rotated about the center line penetrating the coiled member in the longitudinal direction following the developing roller, and the permanent magnet in the developing roller is rotated. It is magnetized by a magnetic force, whereby the developer is conveyed in the longitudinal direction while adsorbing the developer.
JP-A-8-50406 (paragraphs [0015] to [0017] and FIGS. 4 and 5)

  By the way, in the developing device as described in Patent Document 1, since the coil-shaped member is in direct contact with the peripheral surface of the developing roller, the peripheral surface of the developing roller may be damaged. Has a point.

  The coiled member is used instead of the forcedly driven stirring and conveying means, but the stirring ability is not improved as compared with the forcedly driven stirring and conveying means, and the coiled member is driven by the developing roller. Therefore, there is a problem that the agitating / conveying capacity is rather lowered.

  Further, since the coil-shaped member is magnetized by the permanent magnet of the developing roller and adsorbs the developer, there is also a problem that the developer easily aggregates due to the developer clinging to the coil-shaped member. . When the agglomerated developer is peeled off from the coil-shaped member onto the peripheral surface of the developing roller, the aggregated developer is supplied to the photosensitive drum, whereby an appropriate toner image is formed on the peripheral surface of the photosensitive drum. There is an inconvenience that it cannot be formed.

  Further, the present invention is not directly related to the contents of Patent Document 1, but has a problem of increasing the developer loading capacity after making the developing device compact.

The present invention has been made in view of such a situation, and improves the stirring and conveying ability of the developer while preventing the peripheral surface of the developing roller from being damaged, so that the peripheral surface of the photosensitive drum is always appropriate. An object of the present invention is to provide a developing device capable of forming a toner image and increasing the developer loading capacity while reducing the size of the developing device.

First aspect of the present invention, a 攪拌搬feed means you convey the developer while stirring, a predetermined developing roller for supplying to the photosensitive member receives a part of the developer being conveyed by the攪拌搬feed means in the developing apparatus the developing apparatus comprising been furnished in the body, between the wall and the stirring conveying means of the inner part of the developing device body is driven to drive the person the stirring拌搬feeding means without being journalled agitating auxiliary member which rotates with al will be, the agitating auxiliary member is composed of a metal core member, an elastic material made of covering material coated with the core material, the agitating auxiliary member formed in a cylindrical shape The covering material is provided with a cylindrical portion and a stirring portion provided adjacent to the cylindrical portion and having a stirring member .

According to the present invention, the developer loaded into the developing device main body part while being agitated by 攪拌搬feed means is fed to the photosensitive member through the developing roller, whereby the toner image on the peripheral surface of the photosensitive member To form. Residual developer not used for toner image formation is circulated and conveyed while being stirred in the current image device.

Then, stirring auxiliary member loaded between the wall and the 攪拌搬feeding means of the inner portion of the developing device main body, without being journalled, i.e. so as to follow the drive of the first stirring conveying means floating state order to that is configured, the current Zozai is always to be agitated, be more reliably equalized with additive effect of the 攪拌搬feed means by the rotation of the agitating auxiliary member in addition to 攪拌搬feed means The

Further, by adopting the agitation auxiliary member, without employing the 攪拌搬feed means big as the conventional, the corners of the developer storage space is put that攪拌搬feed means to the developing device main body exists it becomes possible to stir even a developer, a developing apparatus, an amount equivalent to using a large攪拌搬feed means, so obtaining achieving downsizing while ensuring a large developer loading capacity.

The agitation assisting member is composed of a metal core material and a coating material made of an elastic material covering the core material, and the surface side includes a coating material made of an elastic member made of an elastomer such as rubber. because it is formed, be freely floating in the developing device body, inconveniences damaging the wall surface of the inner portion of 攪拌搬feeding means and the developing device body does not occur.

Further, the agitating auxiliary member formed in a cylindrical shape, the covering member includes a cylindrical portion, provided adjacent to the cylindrical portion, due to the provision of a stirring section having a stirring member, the stirring auxiliary member 攪 Since the developer is agitated by the agitating member of the agitating portion of the agitation assisting member by following the drive rotation of the agitating and conveying means and rotating around the axis, the agitation assisting member exists in the developing device main body. Compared with the case where it does not, it makes uniform more reliably.

According to a second aspect of the present invention, there is provided a predetermined developing device main body including an agitating / conveying means for agitating and conveying the developer and a developing roller for receiving a part of the developer being conveyed by the agitating / conveying means and supplying the part to the photosensitive member. In the developing device built in,
Between the inner wall surface of the developing device main body and the stirring and conveying means, a stirring auxiliary member that rotates following the driving of the stirring and conveying means without being pivotally supported is provided.
The developing device in the inside of the wall of the body, the current image device you characterized in that scraping unit for scraping off the developer adhered to the surface of the agitating assisting member is provided.

According to the invention, by the agitating auxiliary member by driving the 攪拌搬feed means driven to rotate, scraping portion provided on the wall surface of the inner portion of the developing device main body in contact with the peripheral surface of 攪拌搬feed means Since the developer adhering to the surface of the stirring assisting member is scraped off, it is possible to effectively prevent the inconvenience that the developer adheres to the surface of the stirring assisting member and aggregates.

According to a third aspect of the invention, in the invention of claim 1 or 2, wherein the agitating auxiliary member is positioned above the agitating and transporting means, the surface of the stirring conveyance means sinks in the developer under its own weight It is characterized by being comprised so that it may contact | abut.

According to the present invention, stirring the auxiliary member is made to reliably contact with the surface of the 攪拌搬feed means, easily always reliably rotated in contact with the person the agitation拌搬feeding means.

The invention according to claim 4 is the invention according to claim 2 , wherein the agitation assisting member is composed of a metal core material and a coating material made of an elastic material covering the core material. Is.

According to this invention, the stirring auxiliary member is made of a metal core and a cover made of an elastic material covering the core, and the surface side is made of an elastic member made of an elastomer such as rubber. because it is formed with a wood, be freely floating in the developing apparatus main body, it does not occur inconvenience such as damaging the wall of the inner portion of the first stirring and conveying means and the developing apparatus. Moreover, since the stirring assisting member is formed by coating a metal core with an elastic material, the specific gravity of the stirring assisting member is easily set by adjusting the weight of the core.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the agitating and conveying means includes a first agitating and conveying means that conveys the developer while stirring, and the first agitating and conveying means. A second agitating and conveying means that is provided adjacently and receives the developer from the first agitating and conveying means on the downstream side in the developer conveying direction by the first agitating and conveying means and agitates it in the reverse direction; The first agitating / conveying means is provided at a position above the second agitating / conveying means, and returns the developer to the first agitating / conveying means on the downstream side in the developer conveying direction by the second agitating / conveying means. Returning means is provided, and the developer returning means is a developer pumping means comprising a columnar rotating body that rotates around an axis and a predetermined number of magnetic poles provided in the circumferential direction of the rotating body. It is characterized by being

  According to the present invention, the developer conveyed to the downstream end of the second agitating / conveying means is pumped up to the first agitating / conveying means while being adsorbed by the magnetic force by the driving of the developer pumping means. It is circulated and conveyed between the stirring and conveying means. And since the 1st stirring conveyance means is provided in the upper position rather than the said 2nd stirring conveyance means (namely, since it is a two-story system), the 1st and 2nd conveyance means was arranged in parallel in the horizontal direction ( In other words, the width of the developing device can be made narrower than that of the one-story building), thereby reducing the occupation area of the installation floor surface of the image forming apparatus and contributing to downsizing.

According to the first aspect of the invention, agitation auxiliary member loaded between the wall and the 攪拌搬feeding means of the inner portion of the developing device body, 攪in floating state that is not pivotally supported to nothing拌搬feed means order to that is configured to rotate by being driven by the driving of the developer is always agitated by stirring the auxiliary member in addition to 攪拌搬feed means, in additive effect with 攪拌搬feed means it is possible to reliably equalize the current image agent.

Further, since the stirrer member contains a heavy metal material , the developer aggregates due to the carrier being magnetically attached to the stirrer member, thereby causing the developer to become non-uniform. Can be reliably prevented.

Further, by adopting the agitation auxiliary member, without employing the 攪拌搬feed means big as the conventional, the corners of the developer storage space is put that攪拌搬feed means to the developing device main body exists it becomes possible to stir even a developer, without a large攪拌搬feed means minute, it is possible to reduce the size of the developing device while ensuring a large developer loading capacity.

The stirring assisting member, which is formed by coating a metal core with an elastic material, be freely floating in the developing device body, inconveniences damaging the 攪拌搬feeding means and the wall surface Can be reliably prevented.

Further, by rotating in a driven agitating auxiliary member is a rotation of the 攪拌搬feed unit around the axis, to be agitated by the agitating member of the agitation portion of the agitation support member, the developer in the developing device main body and more It can be made uniform effectively.

According to the second aspect of the present invention, on the wall surface of the inner portion of the developing device body, since the scraping portion for scraping off the developer adhered to the surface of the agitating auxiliary member is provided, the drive of 攪拌搬feed means in by stirring auxiliary member is rotated, the developer adhering to the surface of the agitating auxiliary member is scraped by the scraping portion provided on the wall surface of the inner portion of the developing device main body, whereby the developer is stirred auxiliary It is possible to effectively prevent the occurrence of inconvenience such as adhesion and aggregation on the surface of the member.

According to the third aspect of the present invention, stirring assisting member, before located above the Ki搬 feed means, because it is configured to abut the surface of the stirring conveyance means sinks in the developer under its own weight , will be surely contact with the surface of the 攪拌搬feeding means, can be reliably rotated always in contact with the person the agitation拌搬feeding means.

According to the fourth aspect of the present invention, stirring the auxiliary member, which is formed by coating a metal core with an elastic material, be freely floating in the developing device body,攪拌搬feeding means It is possible to reliably prevent the occurrence of inconvenience that damages the wall surface.

According to the fifth aspect of the present invention, the first agitating / conveying means is provided at a position above the second agitating / conveying means, so that the first and second conveying means are compared with those arranged in parallel in the lateral direction. In addition, it is possible to reduce the width of the developing device, thereby making it possible to reduce the occupation area of the installation floor surface of the image forming apparatus and to contribute to downsizing.

  Before describing the developing device according to the present invention, the term “developer” in the present invention will be defined. “Developer” refers to a two-component mixture of “toner” and “magnetic carrier”. The “toner” is a fine powder having a particle size of about 6 to 12 μm in which additives such as a colorant, a charge control agent, and wax are dispersed in a binder resin. The “magnetic carrier” refers to magnetic particles having a particle size of about 60 to 200 μm, such as Fe 3 O 4, for charging the toner.

  The “toner” is a consumable that is appropriately replenished from the toner cartridge to the developing device, whereas the “carrier” is loaded in a predetermined amount in the developing device in advance, and is circulated and used without being consumed. Therefore, it is not normally replenished.

  FIG. 1 is a side view illustrating a color image forming apparatus of a quadruple tandem developing system to which a developing device 20 according to the present invention is applied. As shown in FIG. 1, the image forming apparatus 10 includes an image forming unit 11 that plays a central role, a transfer belt unit 12 disposed below the image forming unit 11, and the transfer belt unit 12 mounted thereon. A sheet storage unit 14 for storing sheets to be fed between the image forming unit 11 and the transfer belt unit 12 through the sheet supply unit 13, and the image forming unit 11 and the transfer belt. The fixing unit 15 disposed immediately downstream of the unit 12 (left side in FIG. 1) is formed by being mounted in a box-shaped device main body 16 having a rectangular parallelepiped shape in appearance.

  The image forming unit 11 performs a toner image transfer process on the paper supplied from the paper storage unit 14 via the paper supply unit 13, and in the present embodiment, on the upstream side (the right side in FIG. 1). ), A yellow unit 11Y, a magenta unit 11M, a cyan unit 11C, and a black unit 11K which are sequentially arranged from the downstream side to the downstream side. Each of the units 11Y, 11M, 11C, and 11K is positioned in a predetermined relative positional relationship with respect to the device main body 16 and each part, and is mounted in the device main body 16.

  Each unit 11Y, 11M, 11C, and 11K includes a developing device 20 and a photosensitive drum 111, respectively. Each photosensitive drum 111 is supplied with toner from the corresponding developing device 20 and rotates in the clockwise direction in FIG.

  A charger 112 is provided at a position on the upper left side in FIG. 1 of each photoconductor drum 111, and an exposure device 113 is provided at a position on the upper right side in FIG. Each photosensitive drum 111 is charged uniformly by the charger 112, and LED light based on image data input from a document image reading device (not shown) is charged from each exposure device 113. By irradiating the peripheral surface of the subsequent photosensitive drum 111, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 111. By supplying toner from the developing device 20 to the electrostatic latent image, a toner image is formed on the peripheral surface of the photosensitive drum 111.

  The transfer belt unit 12 is provided at a position below the image forming unit 11 so as to correspond to each photosensitive drum 111. The transfer belt unit 12 includes a base 121 mounted on the paper feeding unit 13 and a transfer belt 122 supported by the base 121 and rotating in the counterclockwise direction in FIG. The transfer belt 122 is transferred to a slightly upper position between the driving roller 133 provided at the left end of the base 121 in FIG. 1, the driven roller 134 provided at the right end, and between the driving roller 133 and the driven roller 134. The belt 122 is wound around a plurality of transfer rollers 135 disposed opposite to the respective photosensitive drums 111 via a belt 122, and circulates by the rotational driving of the driving roller 133.

  Each of the transfer rollers 135 is pressed against the corresponding photosensitive drum 111 via the transfer belt 122, so that the transfer from the photosensitive drum 111 to the sheet conveyed by the transfer belt 122 is reliably performed. It has become. Further, a cleaning device 114 for removing residual toner on the circumferential surface of the photosensitive drum 111 and cleaning the photosensitive drum 111 is provided at a lower left position in FIG. 1 of each photosensitive drum 111. The peripheral surface of the photosensitive drum 111 cleaned by the cleaning device 114 is directed to the charger 112 for a new charging process.

The sheet feeding unit 13 picks up one sheet at a time from a bundle of sheets loaded in the sheet storage unit 14 and sends it between the photosensitive drum 111 and the transfer belt 122. In the present embodiment, the transfer belt The unit 12 is inserted into and removed from the device main body 16 integrally. The sheet feeding unit 13 is disposed at a position facing a predetermined pair of conveying rollers 131 for conveying the uppermost sheet picked up from the sheet bundle in the sheet storage unit 14 and the transfer belt 122 and the photosensitive drum 111. In addition, a registration roller pair 132 and the like for feeding the paper after positioning the paper are provided.

  Then, the paper picked up from the paper storage unit 14 is supplied onto the transfer belt 122 via the conveying roller pair 131 and the registration roller pair 132, and the image forming unit 11 and the transfer belt unit are rotated along the circumference of the transfer belt 122. 12 and the toner images on the photosensitive drums 111 of the image forming units 11Y, 11M, 11C, and 11K are sequentially transferred onto the paper during the passage.

  The sheet on which the toner image has been transferred is introduced into a fixing unit 15 having a fixing roller pair 151, and the color on which toner is fixed on the sheet by a heat fixing process by passing between the heated fixing roller pair 151. An image is formed. The sheet with the color image for which the fixing process has been completed is discharged to a discharge unit 161 formed on the top of the apparatus main body 16 through a predetermined conveyance path.

  2 and 3 are perspective views showing an embodiment of the developing device 20 according to the present invention, which is suitable for application to such an image forming apparatus 10, and FIG. FIG. 3 shows a state in which the lid 29 is attached to the developing device main body 21. 4 is a cross-sectional view taken along line AA in FIG. 3, and FIG. 5 is a cross-sectional view taken along line BB in FIG. 2 to 5, the XX direction is referred to as the width 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 forward, and the + Y direction is forward. It is called the back.

  As shown in these drawings, the developing device 20 includes a developing device main body 21 and a lid 29 that closes the upper surface opening of the developing device main body 21. In the developing device main body 21, as shown in FIG. 4, an upper screw feeder (first stirring and conveying means) 30 and a lower screw feeder (second agitating and conveying means) positioned almost directly below the upper screw feeder 30 are provided. 40, a pumping roller (pumping means (developer returning means)) 50 positioned slightly rearward of a substantially central portion between the upper and lower screw feeders 30 and 40, and a position in front of the lower screw feeder 40. The developing roller 60 is disposed in a predetermined positional relationship.

  An upper stirring chamber 235, which will be described later, is a space in which the upper screw feeder 30 of the developing device main body 21 is mounted. The upper stirring chamber 235, which will be described later, is pivotally supported by any one that can move freely in the upper stirring chamber 235. The stirring auxiliary member 70 of the first embodiment is not loaded.

  As shown in FIG. 2, the developing device main body 21 includes a right-side pumping roller mounting portion 22 and an upper screw formed above the left partition plate 231 (FIG. 5) of the pumping roller mounting portion 22. It is divided into a feeder mounting portion 23 and a lower screw feeder mounting portion 24 formed below the partition plate 231.

  As shown in FIG. 4, the pumping roller mounting portion 22 is a portion where the upper and lower screw feeders 30 and 40 and the pumping roller 50 are mounted, and the developing device main body 21 is located on the right side of the developing device main body 21. It is formed so as to occupy approximately 1/4 to 1/5 of the length dimension of 21. In the pumping roller mounting portion 22, the lower screw feeder 40 is disposed substantially directly below the upper screw feeder 30, and the pumping is performed slightly rearward between the upper screw feeder 30 and the lower screw feeder 40. A roller 50 is provided.

  The upper screw feeder mounting portion 23 is a portion to which the upper screw feeder 30 is mounted at the upper part of the partition plate 231 (FIG. 5), and extends from the upper left position of the pumping roller mounting portion 22 toward the left. It is formed in the state.

  The lower screw feeder mounting portion 24 is a portion where the lower screw feeder 40 is mounted at the lower portion of the partition plate 231 and extends from the lower left position of the pumping roller mounting portion 22 toward the left. Is formed.

  As shown in FIG. 4, the pumping roller mounting portion 22 includes a lower arc front wall 221 having a substantially arc shape, and an outer peripheral surface of the pumping roller 50 from a lower edge of the lower arc front wall 221. An inclined bottom plate 222 inclined slightly rearward and upward, and a substantially arc-shaped arcuate rear wall 223 extending from the rear edge of the inclined bottom plate 222 toward the rear upper part of the pumping roller 50; An inclined rear wall 224 that is inclined and extended rearward from the upper edge of the arcuate rear wall 223 and an upper edge of the lower arcuate front wall 221 along the outer peripheral surface of the upper screw feeder 30. An upper arcuate front wall 225 extending upward and a rear edge extending from the upper edge of the lower arcuate front wall 221 toward the rear along the outer peripheral surface of the upper screw feeder 30 Arc-shaped partition plate 226 having a free end, and An intermediate side plate 227 constructed between the left end of the arc-shaped partition plate 226 (the back side in the direction orthogonal to the plane of FIG. 4) and the inclined bottom plate 222 and the arc-shaped rear wall 223; And a right side wall 228 covering the right end (see FIG. 2) of each wall.

  The front portion of the intermediate side plate 227 is provided with a notch 227 a for allowing the lower screw feeder 40 to pass therethrough, and between the rear end edge of the lower arcuate front wall 221 and the lower end edge of the inclined rear wall 224. Is formed with a right communication opening 25 toward a space (upper stirring chamber 235 described later) in which the upper screw feeder 30 is provided. A pumping conveyance path 26 that pumps the developer toward the upper stirring chamber 235 is formed between the outer peripheral surface of the pumping roller 50 and the inner surface of the arcuate rear wall 223.

  As shown in FIG. 5, the upper screw feeder mounting portion 23 includes a partition plate 231 extending from the arc-shaped partition plate 226 (FIG. 4) toward the right side (the back side of the paper surface of FIG. 4), An inclined rear wall 232 that extends obliquely upward from the rear edge of the partition plate 231 slightly toward the rear, and a front wall 233 that extends upward from the front edge of the partition plate 231. And a partition wall 231, an inclined rear wall 232, and a left side wall 234 installed on the left end of the front wall 233. An upper stirring chamber 235 for stirring the developer by the upper screw feeder 30 is formed in a space surrounded by the partition plate 231, the inclined rear wall 232, the front wall 233 and the right side wall 228 (FIG. 2). The left side wall 234 extends to the lower screw feeder mounting portion 24.

  As shown in FIG. 5, the lower screw feeder mounting portion 24 is a portion where the lower screw feeder 40 is mounted. The lower screw feeder mounting portion 24 faces downward from the rear edge of the partition plate 231 through the rear position of the lower screw feeder 40. A rear wall 241 extended from the rear wall 241, a bottom plate 242 that extends slightly forward from the rear wall 241, and a front edge of the partition plate 231 that extends toward the peripheral surface of the developing roller 60. And a developer regulating blade 243 provided.

In the space surrounded by the rear wall 241, the bottom plate 242, the developer regulating blade 243, the developing roller 60, the left side wall 234 and the right side wall 228, and the intermediate side plate 245 (FIG. 2), the lower screw A lower stirring chamber 244 for stirring the developer is formed by the feeder 40. Further, the developing roller 60 protrudes forward from a straight line connecting the front end edge of the developer regulating blade 243 and the front end edge of the bottom plate 242, and a part of the peripheral surface of the protruding portion is the photosensitive drum 111. It is made to oppose.

  The partition plate 231 is provided with a left communication opening 27 at the left end thereof, and the developer in the upper stirring chamber 235 is supplied to the lower stirring chamber 244 through the left communication opening 27. .

  The developer regulating blade 243 cuts off the developer spike adhering to the peripheral surface of the developing roller 60 (cuts off the tip end side of the developer spike formed along the lines of magnetic force from the magnetic poles provided on the developing roller 60. ), And a slight gap of a predetermined dimension is formed between the leading edge of the developer regulating blade 243 and the peripheral surface of the developing roller 60. Therefore, the developer magnetically attached to the peripheral surface of the developing roller 60 in the lower stirring chamber 244 is cut off by the developer regulating blade 243 by the counterclockwise rotation around the axis of the developing roller 60, thereby developing the developer. The circumferential surface of the roller 60 faces the circumferential surface of the photosensitive drum 111 in a state where a developer layer having a predetermined thickness is uniformly laminated.

  In the example shown in FIG. 5, a toner scattering prevention cover 246 that is openable and closable with respect to the peripheral surface of the developing roller 60 is provided at a position in front of the developer regulating blade 243, and the toner scattering prevention cover 246 is closed. Thus, the scattered toner from the peripheral surface of the developing roller 60 exposed to the outside from the lower stirring chamber 244 is prevented from diffusing into the device main body 16 (FIG. 1) of the image forming apparatus 10.

  The lid 29 closes the upper surface opening of the developing device main body 21 as shown by an arrow in FIG. 2, and is as shown in FIG. 3 in the closed state. An opening / closing mechanism 291 for opening / closing an opening / closing plate with respect to the upper surface opening of the pumping roller mounting portion 22 of the developing device main body 21 is provided on the upper surface of the right end portion of the lid 29. The opening / closing mechanism 291 opens the opening / closing plate in conjunction with the mounting operation when a toner cartridge (not shown) for replenishing toner to the developing device 20 is mounted on the lid 29, while the toner cartridge Is removed from the lid 29 to close the opening / closing plate.

  Accordingly, when the toner cartridge is attached to the developing device 20 via the lid 29, the toner in the toner cartridge is loaded into the developing device main body 21, while the toner cartridge is removed from the lid 29 when the toner cartridge is removed. Toner leakage from the cartridge is prevented.

  As shown in FIG. 2, the upper screw feeder 30 is mounted between the right side wall 228 and the left side wall 234 of the developing device main body 21 so as to run vertically through the pumping roller mounting unit 22 and the upper screw feeder mounting unit 23. . The upper screw feeder 30 includes a screw shaft 31 having end portions penetrating the side walls 228 and 234 so as to be rotatable around an axis, and a spiral blade 32 formed in a spiral shape on the outer peripheral surface of the screw shaft 31. I have. In the present embodiment, as shown in FIG. 6, the spiral blade 32 is formed in a so-called right spiral so as to extend clockwise (clockwise) when viewed from the end surface of the screw shaft 31. Therefore, the upper screw feeder 30 rotates counterclockwise around the screw shaft 31 in FIG. 6 so that the developer is conveyed leftward in the upper stirring chamber 235.

The lower screw feeder 40 is mounted in the developing device main body 21 in a state of passing through the pumping roller mounting portion 22 and the lower screw feeder mounting portion 24 through the notch 227a of the intermediate side plate 227. The lower screw feeder 40 includes a screw shaft 41 having end portions penetrating the side walls 228 and 234 so as to be rotatable around an axis, and a spiral blade 42 formed in a spiral shape on the outer peripheral surface of the screw shaft 41. I have. That is, the lower screw feeder 40 provided at a position relatively close to the developing roller 60 is pivotally supported by the screw shaft 41 and does not contact the developing roller 60.

  In the present embodiment, as shown in FIG. 6, the spiral blade 42 is formed by a left spiral opposite to the spiral blade 32 of the upper screw feeder 30. Accordingly, the lower screw feeder 40 rotates counterclockwise around the screw shaft 41 in FIG. 6 so that the developer is conveyed rightward in the lower stirring chamber 244.

  As shown in FIG. 4, the pumping roller 50 pumps the developer located in the pumping roller mounting portion 22 on the right side of the lower stirring chamber 244 (FIG. 5) through the pumping conveyance path 26 and the right communication opening 25. A pumping roller shaft 51 that passes between the intermediate side plate 227 and the right side wall 228 so as to be rotatable about an axis, and the pumping roller shaft 51. The pumping roller main body 52 is externally fitted concentrically so as to be integrally rotatable, and the covering 53 is externally fitted in close contact with the pumping roller main body 52.

  The pumping roller main body 52 has a plurality of pairs of N poles and S poles formed on the outer peripheral surface thereof at equal pitches in the circumferential direction, and the developer is placed between these N poles and S poles. It is attracted to the outer peripheral surface of the pumping roller 50 in a state along the magnetic field lines to be formed. When the scooping roller 50 rotates around the scooping roller shaft 51 in the counterclockwise direction in FIG. 4, the magnetic carrier in the developer is attracted to the outer peripheral surface of the scooping roller main body 52 through the covering 53. The toner is accompanied by the magnetic carrier, and eventually the developer composed of the magnetic carrier and the toner is pumped up to the upper stirring chamber 235 through the transporting path 26.

  In the present embodiment, the covering 53 is formed of a so-called heat-shrinkable synthetic resin tube that shrinks when heated. A heat-shrinkable tube having an inner diameter (diameter, which is a diameter unless otherwise specified) is set slightly larger than the outer diameter of the pumping roller main body 52 is loosely fitted to the pumping roller main body 52. Thereafter, the tube is thermally contracted by heat treatment such as blowing hot air and is brought into close contact with the outer peripheral surface of the pumping roller main body 52, thereby forming a covering 53.

  As shown in FIG. 5, the developing roller 60 penetrates between the intermediate side plate 245 (FIGS. 2 and 4) of the lower screw feeder mounting portion 24 and the left side wall 234 of the developing device main body 21. A developing roller shaft 61 is provided, and a developing roller main body 62 is fitted on the developing roller shaft 61 so as to be concentric and integrally rotatable.

  In the developing roller main body 62, a plurality of magnetic poles are formed over the entire circumference along the peripheral surface from the inside, and the toner is developed by attracting the carrier by the attracting force of these magnetic poles and entraining the toner with this. It is applied uniformly and effectively to the peripheral surface of the roller body 62.

  The developing roller shaft 61 is set at an installation position so as to be located at a substantially central portion of a straight line connecting the lower end edge of the developer regulating blade 243 and the front end edge of the bottom plate 242 of the lower screw feeder mounting portion 24. Minutes protrude from the lower stirring chamber 244 to the outside.

  The developing roller 60 is configured to rotate counterclockwise in FIG. 5 around the developing roller shaft 61, and is laminated on the peripheral surface of the developing roller main body 62 by such rotation, and is predetermined by the developer regulating blade 243. The developer whose thickness is regulated is opposed to the peripheral surface of the photosensitive drum 111 that rotates clockwise about the axis, and only a part of the toner in the developer is exposed along the electrostatic latent image. While being supplied to the body drum 111, the carrier in the developer and the remaining toner are collected in the lower stirring chamber 244 while adhering to the peripheral surface of the developing roller body 62.

  In the present invention, as shown in FIGS. 2 and 3, a joint member 611 is provided concentrically with the developing roller shaft 61 at the left end portion of the developing roller shaft 61, and a drive motor (not shown) is provided on the joint member 611. By connecting the drive shafts, the drive motor is driven to rotate in a predetermined direction. The rotation of the developing roller shaft 61 via the joint member 611 is transmitted to the upper screw feeder 30 and the lower screw feeder 40 via a gear mechanism (not shown) provided at an appropriate position on the left side wall 234 of the developing device main body 21. At the same time, the driving of any one of the upper screw feeder 30 and the lower screw feeder 40 is transmitted to the pumping roller 50 via a gear mechanism (not shown) provided at the right end of the developing device 20. ing.

  On the upper surface side of the arc-shaped partition plate 226, as shown in FIG. 4, a scraper 80 whose installation position is set so that the tip abuts against the covering 53 of the pumping roller 50 is provided. The scraper 80 is set so that the direction toward the contact point P with respect to the covering 53 is substantially coincident with the tangential direction of the scooping roller 50 at the contact point P, and the leading edge surface of the scraper 80 is the scooping roller shaft 51. The developer adhering to the peripheral surface of the pumping roller 50 that rotates counterclockwise around the front faces the developer, thereby reliably scraping off the developer adhering to the peripheral surface of the covering 53. It can be done.

  In the present embodiment, the scraper 80 is attached to the upper surface of the arc-shaped partition plate 226 via a double-sided tape (a tape formed by applying an adhesive on the front and back surfaces). Is not limited to being attached to the arc-shaped partition plate 226 via a double-sided tape, and may be attached to the arc-shaped partition plate 226 via an adhesive or may be welded. It may be fixed with screws.

  In the present invention, as shown in FIGS. 2 and 5, the stirring assisting member 70 is freely supported in the upper stirring chamber 235 in the upper screw feeder mounting portion 23 of the developing device main body 21 without being supported by a shaft or the like. It is loaded in a state where it can move freely, that is, located above the upper screw feeder 30, sinks into the developer by its own weight, and comes into contact with the surface of the upper screw feeder 30. The stirring assisting member 70 has a cylindrical shape slightly shorter than that of the upper screw feeder 30, and is made of a metal core 71 and a covering material made of an elastic material made of an elastomer such as rubber concentrically covered with the core 71. 72.

  In the present embodiment, soft iron is adopted as the core material 71, but the present invention is not limited to the core material 71 being soft iron, and stainless steel, various iron alloys, aluminum, and the like. A metal material such as an alloy is preferably used, but not only a metal material but also a non-metal material such as ceramic is applicable. In the present embodiment, synthetic rubber is employed as the covering material 72. However, the present invention is not limited to the covering material 72 being synthetic rubber, and soft polyethylene, polypropylene, polyamide, etc. These synthetic resins are preferably used.

  The core material 71 serves as a weight for embedding the stirring assisting member 70 in the developer, and the average specific gravity of the stirring assisting member 70 is the apparent specific gravity of the developer (note that the apparent specific gravity of the developer is , Measured in accordance with JIS-Z2504). By doing so, the stirring assisting member 70 once embedded in the developer does not float from the developer even if it rotates around the axis.

  The agitation assisting member 70 is formed between the spiral blade 32 of the upper screw feeder 30 and the inclined rear wall 232 so that the substantially lower half can be fitted into a narrow space as viewed from the side as shown in FIG. On the other hand, the inclined rear wall 232 is provided with a scraping protrusion (scraping portion) 232a extending in the width direction (direction perpendicular to the paper surface of FIG. 5). Therefore, when the stirring assisting member 70 is driven by the upper screw feeder 30 rotating counterclockwise around the axis and rotated clockwise around the axis, the development adhered to the peripheral surface of the stirring assisting member 70 Since the agent is scraped off by the scraping protrusion 232a, it is possible to reliably prevent the developer from aggregating on the peripheral surface of the stirring assisting member 70 to form a nodule.

  FIG. 6 is a perspective explanatory view for explaining the operation of the developing device 20 according to the present invention, and is a main part related to the present invention (that is, the upper screw feeder 30, the lower screw feeder 40, the pumping roller 50, the stirring auxiliary member). 70 and scraper 80 etc.) only. Note that the direction display by X and Y in FIG. 6 is the same as in FIG.

  The operation of the developing device 20 according to the present invention will be described below with reference to FIG. 6 and FIGS. 1 to 5 as necessary. Incidentally, the white arrow in FIG. 6 indicates the direction of the developer flow. First, when toner is loaded from a toner cartridge (not shown) through the opening / closing mechanism 291 of the lid 29 (FIG. 3) to the right end portion of the upper screw feeder mounting portion 23 in the developing device main body 21, the toner is As the screw feeder 30 rotates counterclockwise around the screw shaft 31, the carrier is conveyed while being stirred leftward in the upper stirring chamber 235 together with the carrier, as indicated by a white arrow.

  At this time, since the peripheral surface of the auxiliary stirring member 70 loaded in the upper stirring chamber 235 is in contact with the peripheral edge of the spiral blade 32 of the upper screw feeder 30, it is driven by the rotation of the upper screw feeder 30. Rotate clockwise around the axis. Then, the developer pushed to the outside of the spiral blade 32 is captured by the stirring assisting member 70 and further stirred by the rotation thereof. Therefore, the developer is further stirred and the carrier and the toner are mixed more uniformly. It will be. The developer adhering to the circumferential surface of the stirring assisting member 70 is scraped off by the scraping protrusion 232a (FIG. 5) protruding from the inclined rear wall 232. It can be surely prevented from agglomerating on the surface to become a nodule.

  Then, the developer conveyed to the left end in the upper stirring chamber 235 falls into the lower stirring chamber 244 from the left communication opening 27 of the partition plate 231 (FIG. 5), and this time, the screw shaft of the lower screw feeder 40. By rotating counterclockwise around 41, the inside of the lower stirring chamber 244 is conveyed rightward by the spiral blade 42. During this conveyance, a part of the developer is supplied to the peripheral surface of the developing roller 60 and is used for toner image formation on the peripheral surface of the photosensitive drum 111. Of the developer adhering to the peripheral surface of the developing roller 60, only the toner is supplied to the photosensitive drum 111, and the carrier is recovered and returned to the lower stirring chamber 244 for reuse.

  The remaining developer that has not been supplied from the developing roller 60 to the photosensitive drum 111 passes through the notch 227a (FIG. 4) in the lower stirring chamber 244 by the rotation of the lower screw feeder 40, and the pumping roller at the right end. The carrier is transported to the mounting portion 22, where the carrier in the developing state is guided by the magnetic lines from the magnetic poles of the pumping roller main body 52 due to the counterclockwise rotation of the pumping roller 50, and is pumped and transported while accompanying the toner. It is pumped to the upper stirring chamber 235 through the passage 26 (FIG. 4). The developer (carrier + toner) pumped up into the upper stirring chamber 235 is conveyed toward the left again by the rotation of the upper screw feeder 30 and circulates in the developing device main body 21.

  The developer pumped up by the counterclockwise rotation of the pumping roller 50 projects from the arc-shaped partition plate 226 (FIG. 4), which is the bottom plate of the upper stirring chamber 235, toward the peripheral surface of the pumping roller 50. In addition, since the tip edge is scraped off by the scraper 80 that is in contact with the peripheral surface of the pumping roller 50 at the contact point P, the aggregation of the developer on the peripheral surface of the pumping roller 50 can be reliably prevented. it can.

  As described in detail above, the developing device 20 according to this embodiment is provided in the developing device main body 21 with the developing roller 60 that supplies the developer to the photosensitive drum 111 and in the vicinity of the developing roller 60. An upper screw feeder 30 that conveys the developer while stirring, a lower screw feeder 40 that is provided above the upper screw feeder 30 and that supplies the developer to the developing roller 60 while being stirred, and a lower screw feeder 40 A pumping roller 50 for returning the developer to the upper screw feeder 30 is provided on the downstream side in the developer conveying direction by the screw feeder 40.

  According to the image forming apparatus 10, the developer loaded in the developing device main body 21 is conveyed toward the downstream side while being stirred by the upper screw feeder 30, and is delivered to the lower screw feeder 40 on the downstream side. Subsequently, while being stirred by the lower screw feeder 40 and being conveyed toward the upstream side of the upper screw feeder 30, the toner is supplied to the photosensitive drum 111 via the developing roller 60 on the way, and toner is thus formed on the peripheral surface of the photosensitive drum 111. Form an image. The remaining developer not used for toner image formation is returned to the upstream side of the upper screw feeder 30 by the pumping roller 50 on the downstream side of the lower screw feeder 40, and is circulated and conveyed in the developing device while being stirred. become.

  The auxiliary stirring member 70 loaded between the inner wall surface of the developing device main body 21 and the upper screw feeder 30 is not pivotally supported but is obliquely above the upper screw feeder 30 and is disposed on the inclined rear wall 232 and the upper portion. It is arranged in a V-shaped space in the upper stirring chamber 235 that is V-shaped in a side view partitioned by the screw feeder 30 and is heavier than the developer (that is, when compared with the same volume, the stirring auxiliary member Since 70 is heavier than the developer), it always comes into contact with the surface of the upper screw feeder 30 in a state where it is submerged in the developer, thereby being driven by the drive of the upper screw feeder 30. There is no inconvenience that the stirring assisting member 70 is lifted above the developer and does not rotate when the developer is loaded in the main body 21.

  Therefore, since the stirring assisting member 70 can be driven in a state where it is always in contact with the upper screw feeder 30, the developer composed of toner and carrier is also fed by the stirring assisting member 70 in addition to the upper screw feeder 30. The developer is always stirred, and the additive effect can thereby make the developer more uniform.

  Further, by adopting the stirring assisting member 70, a developer storage space (upper stirring chamber) in which the upper screw feeder 30 in the developing device main body 21 exists can be used without employing a large stirring and conveying means conventionally employed. 235), it is possible to stir the developer in every corner, so that a large developer loading capacity can be secured and the developing device 20 can be made compact because the large stirring and conveying means is not used. .

  In this embodiment, since the upper screw feeder 30 in which the spiral blades 32 are formed around the screw shaft 31 is employed as the first agitating and conveying means, the agitation assisting member 70 includes the upper screw feeder 30. It is possible to make contact with the spiral blade 32 in a stable state, whereby the spiral blade 32 can rotate well following the rotation around the axis of the spiral blade 32.

  Further, since the stirring assisting member 70 is formed by covering a core 71 made of a material heavier than the developer with a covering 72 made of an elastic material made of an elastomer such as rubber, Can be prevented from causing inconveniences such as damaging the wall surfaces of the upper screw feeder 30 and the developing device main body 21, and by adjusting the weight of the core 71, the stirring assisting member 70 can be prevented. Specific gravity can be set easily.

  Further, since the inner wall surface (inclined rear wall 232) of the developing device main body 21 is provided with a scraping protrusion 232a that scrapes off the developer attached to the surface of the stirring auxiliary member 70, the upper screw feeder 30 is driven. The developer adhering to the surface of the stirring assisting member 70 is scraped off by the scraping protrusion 232a due to the rotation around the axis of the stirring assisting member 70 that rotates following the rotation, whereby the developer is removed from the surface of the stirring assisting member 70. It is possible to effectively prevent the occurrence of inconvenience such as adhesion and aggregation.

  Further, the upper screw feeder 30 is provided at a position above the lower screw feeder 40, and returns the developer from the lower screw feeder (second stirring and conveying means) 40 to the upper screw feeder (first stirring and conveying means) 30. As the means, a pumping roller (developer pumping means) 50 is employed. The pumping roller 50 includes a cylindrical pumping roller main body 52 that rotates around the pumping roller shaft 51, and the pumping roller main body 52. Since the developer is provided with a predetermined number of magnetic poles provided in the circumferential direction, the developer conveyed to the downstream end of the lower screw feeder 40 is adsorbed by a magnetic force by driving the pumping roller 50, and the upper screw feeder. 30 and is thus circulated and transported between the upper and lower screw feeders 30 and 40 well.

  Since the upper screw feeder 30 is provided at a position above the lower screw feeder 40 (that is, because it is a two-story system), the first and second conveying means are arranged side by side (that is, a one-story building). In comparison with the method, it is possible to reduce the width of the developing device, thereby reducing the area occupied by the installation floor surface of the image forming apparatus 10 and contributing to downsizing. In particular, in the tandem type image forming apparatus 10 shown in FIG. 1, since the developing devices 20 are provided in quadruple, the effect of reducing the occupied area of the image forming apparatus 10 is increased.

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

  (1) FIG. 7 is a partially cutaway perspective view showing another embodiment of the stirring assisting member, (A) is the stirring assisting member of the second embodiment, and (B) is that of the third embodiment. The stirring auxiliary members are shown. In these embodiments, the point which provided the stirring part provided with the stirring function in a part of coating | covering material 72 is different from the stirring auxiliary member 70 of 1st Embodiment.

  First, the stirring assist member 70 ′ of the second embodiment is formed of a rod-shaped core material 71 and a covering material 72 concentrically covered with the core material 71. Although it is the same as that of the member 70, the point by which the several cylindrical part 721 in which the coating | covering material 72 was formed with the predetermined pitch over the longitudinal direction and the stirring part 722 formed between the adjacent cylindrical parts 721 are provided. This is different from the stirring assisting member 70 of the first embodiment.

  The stirrer 722 protrudes outward in the radial direction from a small cylindrical part 723 having a smaller diameter dimension fitted to the core 71 than that of the cylindrical part 721 and the peripheral surface of the small cylindrical part 723. And a plurality of stirring fins (stirring members) 724 installed between adjacent cylindrical portions 721. In the example shown in FIG. 7A, four stirring fins 724 are provided at equal intervals in the circumferential direction, but the number is not limited to four, but one, two, or three It may be 5 or more.

According to the stirring assisting member 70 ′ of the second embodiment, the development in the upper stirring chamber 235 (FIGS. 2 and 5) is performed by the driven rotation around the axis of the stirring assisting member 70 ′ by the driving rotation of the upper screw feeder 30. Since the agent is stirred by the stirring fins 724 of the stirring unit 722 of the covering material 72 in addition to the upper screw feeder 30, the agent is more reliably stirred than the stirring auxiliary member 70 in which the stirring unit 722 is not provided.

  Next, the auxiliary stirring member 70 ″ of the third embodiment is similar to the second embodiment in that the covering material 72 is composed of a cylindrical portion 721 and an agitating portion 722 as shown in FIG. However, it is different from that of the second embodiment in that a spiral fin (stirring member) 725 is formed around the small cylindrical portion 723 as the stirring portion 722.

  According to the agitation assisting member 70 ″ of the third embodiment, the developer in the upper agitating chamber 235 is agitated by the spiral fins 725 by the rotation around the axis of the agitation assisting member 70 ″ and simultaneously directed toward the downstream side. Therefore, the developer is transported more smoothly without being retained in the upper stirring chamber 235 in addition to the action of the auxiliary stirring member 70 ′ of the second embodiment.

  (2) In the above embodiment, the upper screw feeder (first stirring and conveying means) 30 and the lower screw feeder (second stirring and conveying means) 40 are arranged side by side in the vertical direction. The first stirring / conveying means and the second stirring / conveying means are not limited to be arranged in the vertical direction, and may be arranged in the horizontal direction or in the oblique direction.

  (3) In the above embodiment, the cylindrical auxiliary members 70, 70 ', 70 "are employed as the stirring auxiliary members 70, 70', 70", but the present invention is limited to the cylindrical auxiliary members. 8, the spherical shape (stirring auxiliary sphere 90) as the fourth embodiment may be used as shown in Fig. 8. The stirring auxiliary sphere 90 is heavier than the developer provided at the center position. For example, a weight sphere 91 made of metal and a coated sphere 92 made of an elastic material covering the weight sphere 91 are set. By setting the weight of the weight sphere 91 appropriately, the specific gravity of the stirring assist sphere 90 is increased. Is set larger than the apparent specific gravity of the developer.

  The diameter dimension of the covering sphere 92 is set to be slightly larger than the gap dimension between the opposing surfaces between the screw shaft 31 of the upper screw feeder 30 and the inclined rear wall 232 of the developing device main body 21. It is designed to prevent spilling downward from the gap. Incidentally, a stopper (not shown) is provided at the downstream end of the upper stirring chamber 235 to prevent the stirring auxiliary sphere 90 from falling from the left communication opening 27 (卯 6) to the lower stirring chamber 244.

  According to the stirring auxiliary sphere 90, the stirring auxiliary sphere 90 rolls by the driving rotation of the upper screw feeder 30, so that the developer in the upper stirring chamber 235 is well stirred by the rolling of the stirring auxiliary sphere 90. The

  Further, if the weight sphere 91 is embedded in an eccentric position off the center of the covering sphere 92, the stirring assist sphere 90 becomes irregular in rolling operation due to the center of gravity being offset. A good stirring effect can be obtained.

  (4) In the above-described embodiment, the upper stirring chamber 235 inclined rear wall 232 of the developing device main body 21 is provided with the scraping protrusion 232 a that scrapes off the developer attached to the peripheral surface of the stirring auxiliary member 70. However, the present invention is not limited to the provision of the scraping protrusion 232a on the inclined rear wall 232, and may not be particularly provided.

(5) In the above embodiment, the upper screw feeder 30 and the lower screw feeder 40 are employed as the first and second agitating and conveying means. However, in the present invention, the first agitating and conveying means is a screw feeder. However, the present invention is not limited thereto, and a plurality of stirring rods may be provided on the shaft. When using a screw feeder,
In addition to the spiral wing, a combination of fins on the shaft and imparting transportability may be attached.

  (6) In the above-described embodiment, the covering 53 is covered in close contact with the peripheral surface of the pumping roller main body 52, but the present invention is limited to covering the covering roller 53 with the covering roller 53. However, when a tough material that is not easily damaged is used as the pumping roller main body 52, the pumping roller main body 52 may not be covered with the covering 53. Further, instead of covering the roller body 52 with the covering 53, the peripheral surface of the roller body 52 may be coated with a predetermined material.

  In order to confirm the effect of the stirring auxiliary member 70, the stirring auxiliary member 70 was not applied when the stirring auxiliary member 70 was applied in the upper stirring chamber 235 (FIG. 5) of the developing device main body 21 (Example). A comparative test was conducted to examine whether or not there is a difference in the stirring effect of the developer with respect to the case (comparative example).

In this comparative test, after copying 10,000 sheets of an A4 size character document having an image density of 5%, the toner in the developer stored in various locations in the developing device main body 21 is used. The ratio (wt%) is measured, and the preconditions of the comparative test are as follows. (1) Used developer-Toner (polyester resin)
Average particle size: 9.0 μm
Apparent specific gravity: 0.4
・ Carrier (Mn-Mg type)
Average particle size: 60.0 μm
Apparent specific gravity: 2.0
-Average apparent specific gravity of developer: 1.8
Mixing ratio Toner: Carrier = 5.0 wt%: 95.0 wt
(2) Sampling position of developer. Three locations at the upper portion of the developing roller 60 in the lower screw feeder mounting portion 24 (FIG. 5) of the developing device main body 21 and at the center and both ends in the longitudinal direction. 21 in the upper stirring chamber 235 between the upper screw feeder 30 and the inclined rear wall 232 at three points at the center and both ends in the longitudinal direction. (3) Sampling points 5 points at each sampling position.

  The results of a comparative test conducted based on such preconditions are as shown in Table 1.

  As can be seen from Table 1, when the sampling position is at the upper part of the developing roller 60, the weight ratio of the toner in the developer is 5.1 wt% on average, the maximum value is 5.4 wt%, and the minimum value is 4. In contrast, in the case of the comparative example, the weight ratio of the toner in the developer is 5.0 wt% on average, the maximum value is 5.4 wt%, and the minimum value is 4.6 wt%. There is no great difference between the examples and the comparative examples.

  On the other hand, when the sampling position is a space between the upper screw feeder 30 and the inclined rear wall 232, in the embodiment, the weight ratio of the toner in the developer is 5.0 wt% on average and the maximum value is 5 In the case of the comparative example, the weight ratio of the toner in the developer is 5.9 wt% on the average value, and the maximum value is 6.8 wt% and the minimum value. The value is 5.0 wt%, and it can be seen that the comparative example has a very large variation in the toner ratio, whereas the embodiment has a stable variation in the toner ratio.

  This is because, in the comparative example, the stirring in the upper stirring chamber 235 is not performed well, whereas in the present invention in which the stirring assisting member 70 is applied, the upper portion is acted on by the action of the stirring assisting member 70. This shows that the developer is well stirred in the stirring chamber 235.

1 is a side view illustrating a color image forming apparatus of a quadruple tandem developing system to which a developing device according to the present invention is applied. 1 is a perspective view showing an embodiment of a developing device according to the present invention, and shows a state where a lid is removed from a developing device main body. 1 is a perspective view showing an embodiment of a developing device according to the present invention, and shows a state where a lid is attached to a developing device main body. FIG. 4 is a sectional view taken along line AA in FIG. 3. FIG. 4 is a sectional view taken along line BB in FIG. 3. It is a perspective explanatory view for explaining the operation of the developing device according to the present invention, and shows only main parts (that is, an upper screw feeder, a lower screw feeder, a pumping roller, a scraper, etc.) relating to the present invention. It is a partially notched perspective view which shows other embodiment of a stirring assistance member, (b) shows the stirring assistance member of 2nd Embodiment, (b) shows the stirring assistance member of 3rd Embodiment, respectively. Yes. It is a partially notched perspective view which shows 4th Embodiment of a stirring auxiliary member.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Image forming unit 11Y Yellow unit 11M Magenta unit 11C Cyan unit 11K Black unit 111 Photosensitive drum 112 Charger 113 Exposure device 114 Cleaning device 12 Transfer belt unit 121 Base 122 Transfer belt 13 Paper feed Unit 131 Conveying roller pair 132 Registration roller pair 133 Driving roller 134 Driven roller 135 Transfer roller 14 Paper storage unit 15 Fixing unit 151 Fixing roller pair 16 Device main body 161 Discharging unit 20 Developing device 21 Developing device main body 22 Pumping roller mounting unit 221 Lower part Arc-shaped front wall 222 Inclined bottom plate 223 Arc-shaped rear wall 224 Inclined rear wall 225 Upper arc-shaped front wall 226 Arc-shaped partition plate 227 Middle side plate 227a Notch 228 Right side wall 23 Upper screen New feeder mounting portion 231 Partition plate 232 Inclined rear wall 232a Scraping ridge (scraping portion)
233 Front wall 234 Left side wall 235 Upper stirring chamber 24 Lower screw feeder mounting portion 241 Rear wall 242 Bottom plate 243 Developer control blade 244 Lower stirring chamber 245 Intermediate side plate 246 Toner scattering prevention cover 25 Right communication opening 26 Pumping conveyance path 27 Left communication opening 29 Lid body 291 Opening and closing mechanism 30 Upper screw feeder (first stirring and conveying means)
31 Screw shaft 32 Spiral blade 40 Lower screw feeder (second stirring and conveying means)
41 Screw shaft 42 Spiral blade 50 Pumping roller (pumping means)
51 Pumping roller shaft 52 Pumping roller body (rotating body)
53 Cover 60 Development roller 61 Development roller shaft 611 Joint member 62 Development roller main body 70, 70 ', 70 "Stirring auxiliary member 71 Core material 72 Cover material 721 Column portion 722 Stirring portion 723 Small column portion 724 Stirring fin (stirring member)
725 Spiral fin (stirring member)
80 Scraper (Scraping member)

Claims (5)

And 攪拌搬feed means you convey the developer while stirring, a developing roller for supplying receives a portion to the photoreceptor of the developer being conveyed by the攪拌搬feed means are furnished to a predetermined developing device main body In the developing device
Wherein between the wall surface of the inner portion of the developing device main body and the stirring conveying means, agitating auxiliary member which rotates following provided et al is to drive the person the stirring拌搬feeding means without being journalled,
The stirring assisting member is composed of a metal core material and a coating material made of an elastic material covering the core material,
2. The developing device according to claim 1, wherein the stirring auxiliary member is formed in a columnar shape, and the covering material includes a columnar portion and a stirring portion having a stirring member provided adjacent to the columnar portion . And 攪拌搬feed means you convey the developer while stirring, a developing roller for supplying receives a portion to the photoreceptor of the developer being conveyed by the攪拌搬feed means are furnished to a predetermined developing device main body In the developing device
Between the inner wall surface of the developing device main body and the stirring and conveying means, a stirring auxiliary member that rotates following the driving of the stirring and conveying means without being pivotally supported is provided.
The developing device in the inside of the wall of the body, the current image device you wherein the scraping unit for scraping off the developer adhered to the surface of the agitating auxiliary member is al provided. 3. The agitation assisting member is positioned above the agitation transport unit, and is configured to sink into the developer by its own weight and to come into contact with the surface of the agitation transport unit. Development device. 3. The developing device according to claim 2 , wherein the agitation assisting member is made of a metal core material and a coating material made of an elastic material covering the core material . The agitating / conveying means includes a first agitating / conveying means for conveying the developer while stirring, and the first agitating / conveying means provided adjacent to the first agitating / conveying means on the downstream side in the developer conveying direction by the first agitating / conveying means. A second agitating and conveying means that receives the developer from the agitating and conveying means and conveys the developer while stirring in the reverse direction, and the first agitating and conveying means is provided above the second agitating and conveying means. And a developer returning means for returning the developer to the first stirring and conveying means on the downstream side in the developer conveying direction by the second agitating and conveying means. The developer returning means has a cylindrical shape that rotates about its axis. a rotary member, a developing device according to any one of claims 1 to 4, characterized in developer pumping means der Rukoto comprising a predetermined number of poles provided in the circumferential direction of the rotating body.

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