JP4890273B2 - Development device - Google Patents

Description

  The present invention relates to a developing device that supplies a developer to an image carrier provided in an image forming apparatus to form a developer image.

  2. Description of the Related Art Conventionally, a developing device that is built in an apparatus main body of an image forming apparatus as described in Patent Document 1 is known. In this developing device, a developer is supplied to a photosensitive drum (image carrier) provided in the main body of the image forming apparatus to form a toner image on the peripheral surface thereof. The toner image formed on the peripheral surface of the photosensitive drum is transferred to a sheet supplied in accordance with the rotation around the axis of the photosensitive drum, and the sheet after the transfer process is subjected to a fixing process. It is discharged outside.

The developing device includes a pair of agitation rollers (agitating and conveying members) disposed in parallel with each other in the housing, and a developing roller facing the agitation roller on the downstream side of one agitation roller. A part of the developer in the housing that is conveyed while being stirred so as to circulate between the pair of stirring rollers is fed into the developing roller, and the photosensitive member is rotated from the peripheral surface by rotation around the axis of the developing roller. Supplied to the drum surface.
JP 2005-274924 A

  By the way, since the stirring roller built in the housing of the developing device rotates in a circular motion around the roller axis, the developer in the housing accumulates in a state where the tunnel is dug along the circular locus of the stirring roller. However, there is a problem that the developer may not be reliably conveyed due to the shelf hanging phenomenon.

  In addition, since the corners in the casing are blind spots located outside the rotation trajectory of the stirring roller, the developer stored in the blind spots is not subjected to the stirring force of the stirring roller, thereby causing corners of the casing. There is also a problem that the developer remains deposited on the part. Since the developer having a large diameter and a large specific gravity tends to gradually accumulate in the corners of the housing, as a result, the particle size distribution and charging performance of the developer supplied to the image carrier are the design values. Thus, a proper toner image cannot be formed in a stable state.

  In order to eliminate such inconvenience, in the developing device of Patent Document 1, the bottom of the casing is formed in an arc shape in cross section so as to follow the rotation trajectory of the stirring roller, and the corner is not present. However, when the bottom portion of the casing is formed in an arc shape, a new problem that the capacity of the developing device is reduced correspondingly is raised. If the developing device is enlarged in order to solve this problem, the developing device is made more compact.

  The present invention has been made in order to solve the conventional problems, and it is possible to prevent the developer from hanging on the shelf and depositing on the corners of the housing while avoiding a reduction in the capacity of the housing. An object of the present invention is to provide a developing device capable of consuming a sufficient amount of developer in the casing and allowing a proper toner image to be formed on an image carrier in a stable state. Yes.

The invention described in claim 1 is a developing device for supplying a developer filled in a predetermined casing to the image carrier, and rotates in the casing to supply the developer to the image carrier. An agitating / conveying member that conveys while stirring, the agitating / conveying member having at least part of a polygonal shape of a substantially rouleau when viewed from a direction orthogonal to the developer conveying direction. The casing includes a stirring transport chamber having a wall surface that is close to a state in which each vertex of the polygon of the substantially roulau is slidably contacted or contacted in accordance with the rotation of the stirring member, Each of the agitating and conveying members includes a rotating shaft laid between the pair of end walls, and a plurality of stirring fins concentrically fixed to the rotating shaft so as to be integrally rotatable. The stirring fin has a polygonal shape of the substantially rouleau It is characterized in that a part has a shape.

  According to the developing device having such a configuration, the agitating / conveying member is rotated within a predetermined frame (hereinafter referred to as a holding frame) made of a square, for example, having a radius of curvature of an arc centered on the vertex of the Rouleau polygon. As a result, the center of gravity of the Rouleau polygon is directed in the opposite direction, and the angular velocity is several times the angular velocity of the trunk (for example, if the Rouleau polygon is a triangle, it is 3 times, if it is a pentagon, 5 times, heptagon In the case of, it will circulate at 7 times).

  Therefore, by forming a holding frame in the housing and rotating the stirring and conveying member within the square holding frame, the developer in the holding frame is in the vicinity of the position of the center of gravity of the stirring and conveying member and around it. Forces in the opposite directions from each other act between them, and this effectively stirs the developer. Compared to the conventional one in which the agitating and conveying member rotates around the fixed axis, as in the prior art. The developer in the housing of the developing device is more reliably stirred.

  Further, when the agitating and conveying member is rotated within the holding frame of the housing, the vertex of the polygonal portion of the rouleau in the agitating and conveying member can be brought very close to the corner of the holding frame. The amount of developer that accumulates at the corners in the housing is smaller than that in which the conveying member rotates about the fixed axis.

  Further, when the agitating / conveying member is rotated within the square holding frame, the force applied to the developer located in the vicinity of the agitating / conveying member every rotation of a predetermined angle corresponding to the number of corner portions formed on the agitating / conveying member. Since the direction of the change rapidly (that is, because there is a displacement point), the developer in the housing of the developing device is sufficiently stirred as compared with the conventional stirring and conveying member in which there is no displacement point.

  Incidentally, in claim 1, it is defined that “the shape is substantially a polygonal shape of a roulau when viewed from a direction orthogonal to the developer conveyance direction”. In the case of being recessed to enhance the stirring ability by letting the agent escape, the contour of the cross-sectional shape of the stirring and conveying member in the direction orthogonal to the center line extending in the longitudinal direction is not accurately formed as a Roule polygon. This is because the submerged part may exist. Such a case in which a part of the contour is recessed is defined as “substantially” in order to be included in the technical scope of the invention of claim 1.

  That is, in other words, if the contour line of the figure obtained by projecting the stirring and conveying member from the direction of the center line of the stirring and conveying member is a Rouleau polygon, the invention of claim 1 It can be said that it is included in the technical scope.

In addition , since the agitating and conveying means rotates in a state where each vertex of the Rouleau polygon is close to the contact or close to the wall surface of the agitating and conveying chamber, the developer filled in the agitating and conveying chamber is totally To be stirred.

Further, the stirring and conveying member is mounted on the stirring and conveying chamber by the rotation shaft of the stirring and conveying member being installed between the pair of end walls of the stirring and conveying chamber. Then, the rotating shaft is driven and rotated with the stirring and conveying member mounted in the stirring and conveying chamber, so that the vertex of the stirring fin that has the polygonal shape of the roule is in sliding contact with the inner wall surface of the stirring and conveying chamber. Alternatively, the developer rotates integrally around the rotation axis while approaching a state close to contact, whereby the developer in the agitation transport chamber is supplied to the image carrier while being agitated.

According to a second aspect of the present invention, in the first aspect of the invention, a pair of the agitating and conveying members are arranged in parallel to each other, and the casing is provided with a pair of the agitating and conveying members. A partition plate is provided between the chambers so that the corners of the respective stirring fins are close to sliding contact or close to contact, and at both ends of the partition plate, a passage opening for allowing the developer to pass between the pair of stirring transport chambers. And a supply opening for supplying the developer to the image carrier is provided on a surface of the housing facing the image carrier.

  According to such a configuration, the developer can be rotated by rotating the stirring and conveying members provided in the pair of conveying and stirring chambers arranged in parallel to each other via the partition plate around the rotation axis. Between the agitating and conveying chamber and the other agitating and conveying chamber, it was circulated and conveyed through the passage openings formed at both ends of the partition plate, and a part of the agitating and conveying chamber was provided on the surface of the housing facing the image carrier. It is supplied to the image carrier through the supply opening.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a rotation mechanism for rotating the stirring and conveying member is provided on one side of the end walls facing each other. Is.

  According to such a configuration, by operating the rotating mechanism provided on one side of the opposing end walls of the agitating and conveying chamber, the agitating and conveying member causes the polygonal vertex of the roulette to abut the inner wall surface of the agitating and conveying chamber. Rotates while approaching or close to contact.

According to a fourth aspect of the present invention, in the developing device according to any one of the first to third aspects, the polygon is a triangle.

  According to such a configuration, the developing device has a simple triangular cross-sectional shape of the agitating / conveying member of the developing device while ensuring an excellent stirring action by applying the polygonal shape of the rouleau. Contributes to the reduction of manufacturing costs.

  Further, if the Rouleau polygon is a Rouleau triangle, the amount of movement of the center of gravity is maximized compared to the polygonal Rouleau polygon, and therefore development within the developing device in accordance with the rotation of the developing device. The stirring effect of the agent is improved.

  According to the first aspect of the present invention, the agitating and conveying member provided in the housing of the developing device for agitating the developer and conveying it to the photosensitive drum is viewed from a direction orthogonal to the conveying direction of the developer. Thus, the developer in the housing has no dead zone (dead zone) by the agitating and conveying member by having at least part of the polygonal shape of a substantially roulau, and Since the agitation is more effective than in the past, it is possible to prevent the developer from hanging on the shelves or deposit on the corners of the housing while avoiding a reduction in the volume of the housing, thereby developing the inside of the housing. The agent can be consumed without leaving an excess, and an appropriate toner image can be formed on the image carrier in a stable state.

The agitating / conveying means rotates in a state where each vertex of the roulau polygon is in contact with or close to contact with the wall surface of the agitating / conveying chamber, so that the developer filled in the agitating / conveying chamber is entirely removed. Therefore, it is possible to prevent the inconvenience that the developer is accumulated without being transported in the stirring transport chamber.

In addition, when the agitating and conveying member is mounted in the agitating and conveying chamber, the rotation shaft is driven and rotated, so that the agitating fins having the polygonal shape of the rouleau are in sliding contact with the inner wall surface of the agitating and conveying chamber. Alternatively, the developer rotates integrally around the rotation axis while approaching a state close to contact, whereby the developer in the agitation transport chamber can be supplied to the image carrier while being agitated.

According to the second aspect of the present invention, the developer in the pair of conveyance agitating chambers arranged in parallel to each other via the partition plate is provided between the one agitation conveyance chamber and the other agitation conveyance chamber. Since the developer is circulated and conveyed through the passage openings formed at both ends, the developer is agitated as long as the agitating and conveying member is driven, so that the developer has a sufficient particle size distribution. Can be stirred.

According to the third aspect of the present invention, by operating the rotation mechanism provided on one side of the end walls facing each other of the agitating and conveying chamber, the polygonal vertex of the roulau is placed inside the agitating and conveying chamber. It can be rotated while being brought into close contact with the wall surface or close to contact.

According to the invention of claim 4 , since the Rouleau triangle is adopted in combination with the Rouleau polygon, the developing device contributes to a reduction in manufacturing cost while ensuring an excellent stirring action, The amount of movement of the center of gravity is maximized compared to the triangular shape of the polygonal rouleau, and the stirring effect of the developer in the developing device can be improved.

  FIG. 1 is a side sectional view illustrating an embodiment of a printer 10 to which a developing device 20 according to the present invention is applied. In FIG. 1, the Y-Y direction is referred to as the front-rear direction, in particular, the -Y direction is referred to as the front, and the + Y direction is referred to as the rear.

  As shown in FIG. 1, a printer (image forming apparatus) 10 includes a sheet storage unit 12 that stores sheets P to be subjected to a printing process, and one sheet fed from a sheet bundle P1 stored in the sheet storage unit 12. The printer main body 11 includes an image forming unit 13 that performs an image forming process on the paper P and a fixing unit 14 that performs a fixing process on the paper P subjected to the transfer process in the image forming unit 13. At the same time, a paper discharge unit 15 for discharging the paper P subjected to the fixing process by the fixing unit 14 is provided on the top of the printer main body 11.

  A predetermined number (one in this embodiment) of paper cassettes 121 is provided in the paper storage unit 12 so as to be detachable from the printer main body 11. At the upstream end (front) of the paper cassette 121, a pickup roller 122 that feeds the paper P one by one from the paper bundle P1 is provided. The paper P fed out of the paper cassette 121 by driving the pickup roller 122 is supplied to the image forming unit 13 through the paper feed conveyance path 123 and the registration roller pair 124 provided at the downstream end of the paper feed conveyance path 123. It is supposed to be paper.

  The image forming unit 13 performs a transfer process on the paper P based on image information transmitted from a computer or the like, and is provided so as to be rotatable around a drum core extending in the left-right direction (direction orthogonal to the paper surface of FIG. 1). The charger 132, the exposure device 133, and the toner container 19 are detachably mounted from the position immediately above the photosensitive drum 131 in the clockwise direction along the peripheral surface of the photosensitive drum 131 (image carrier). The developing device 20, the transfer roller 134, and the cleaning device 135 according to the present invention are provided.

  The photosensitive drum 131 is for forming an electrostatic latent image and a toner image along the electrostatic latent image on the peripheral surface, and a level and tough amorphous silicon layer is laminated on the peripheral surface. This makes it suitable for forming these images.

  The charger 132 forms a uniform charge on the peripheral surface of the photosensitive drum 131 rotating in the clockwise direction around the drum core. In the example shown in FIG. A method of applying a charge to the peripheral surface is adopted. It should be noted that instead of the charger 132 as a member for applying a charge to the peripheral surface of the photosensitive drum 131, the peripheral surface is brought into contact with or close to contact with the peripheral surface of the photosensitive drum 131, and the charge is rotated while being driven. You may employ | adopt the charging roller to provide.

  The exposure device 133 irradiates the peripheral surface of the rotating photosensitive drum 131 with a laser beam that is turned on / off based on image data transmitted from an external device such as a computer, and the peripheral surface of the photosensitive drum 131 is thereby generated. The electrostatic latent image is formed on the peripheral surface of the photosensitive drum 131 by erasing the electric charge in the portion irradiated with the laser beam.

  The developing device 20 supplies toner to the peripheral surface of the photosensitive drum 131 to attach the toner to a portion where the electrostatic latent image is formed on the peripheral surface. Is formed. The developing device 20 is configured by mounting various members, which will be described later, in a housing 21 adjacent to the front side of the photosensitive drum 131.

  The toner container 19 is detachably mounted at the front position in FIG. 1 above the casing 21 so as to replenish the casing 21 with a developer (in this embodiment, toner).

Incidentally, the developer includes a so-called one-component system composed only of toner and a so-called two-component system composed of toner and carrier. The toner is a fine powder having a volume average particle size 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 mass average particle diameter of 30 to 200 μm, such as magnetite (Fe ₃ O ₄ ), and is used for charging the toner. When the developer is a one-component developer, fine magnetic particles are contained in the toner.

  The toner is a consumable that is appropriately replenished from the toner container 19 to the developing device 20, whereas a predetermined amount of the carrier is loaded in the developing device 20 in advance, and is circulated and used without being consumed. It is common. In this embodiment, a one-component developer composed only of toner is used as the developer, but the present invention is limited to a one-component developer composed only of toner. Instead, it may be a two-component system composed of a toner and a carrier.

  In front of the top plate 25 of the casing 21 in FIG. 1, a receiving opening 21 a for receiving the toner in the toner container 19 into the casing 21 is provided, and on the front side of the casing 21, A toner supply opening 21 b for supplying toner opened in the left-right direction of the housing 21 (direction orthogonal to the paper surface of FIG. 1) to the photosensitive drum 131 is provided.

  The toner introduced from the toner container 19 through the receiving opening 21a circulates in the housing 21 while being stirred by the driving rotation of first and second agitating and conveying members 301 and 302 described later, and a part thereof Is supplied to the peripheral surface of the photosensitive drum 131 through the peripheral surface of the developing roller 40 that is driven to rotate.

  A layer thickness regulating blade 251, which is suspended from the top plate 25 and has a lower edge facing the peripheral surface of the developing roller 40, is provided above the toner supply opening 21 b, and is anticlockwise around the axis of the developing roller 40. The toner supplied toward the photosensitive drum 131 by the circumferential surface of the developing roller 40 by turning toward the predetermined thickness is passed through a gap between the layer thickness regulating blade 251 and the circumferential surface of the developing roller 40. It is made to become. The first and second agitating / conveying members 301 and 302 and the developing roller 40 are all transmitted with a driving force of a driving motor (not shown) via a predetermined gear mechanism, and thereby rotate synchronously.

  The transfer roller 134 transfers a positively charged toner image formed on the peripheral surface of the photosensitive drum 131 to the paper P with respect to the paper P sent to a position immediately below the photosensitive drum 131. A negative charge having a polarity opposite to that of the toner image is applied to the paper P.

  Accordingly, the paper P that has reached the position immediately below the photosensitive drum 131 is pressed and held between the transfer roller 134 and the photosensitive drum 131, and the toner image on the circumferential surface of the photosensitive drum 131 that is positively charged is negatively charged. The sheet P is peeled off toward the surface of P, whereby the transfer process is performed on the sheet P.

  The cleaning device 135 is for removing the toner remaining on the peripheral surface of the photosensitive drum 131 after the transfer process and cleaning it. The peripheral surface of the photosensitive drum 131 cleaned by the cleaning device 135 goes to the charger 132 again for the next image forming process.

  The fixing unit 14 performs a fixing process by heating the toner image of the paper P subjected to the transfer process by the image forming unit 13. The fixing roller 141 applies heat to the paper P, and a lower part of the fixing roller 141. And a pressure roller 142 arranged opposite to each other. Then, the sheet P after the transfer process is fed toward the nip portion N formed between the fixing roller 141 and the pressure roller 142 and passes through the nip portion N, so that the heat from the fixing roller 141 is transferred. The fixing process is performed. The paper P subjected to the fixing process is discharged to the paper discharge unit 15 through the paper discharge conveyance path 143.

  The paper discharge unit 15 is formed by recessing the top of the printer body 11. A paper discharge tray 151 for receiving the paper P discharged by the bottom plate of the recessed portion is formed.

  2 to 4 are perspective views showing an embodiment of the developing device 20 according to the present invention, FIG. 2 is an exploded perspective view of the internal structure, FIG. 3 is an assembled perspective view of the internal structure, and FIG. It is an assembly perspective view of appearance. 5 is a cross-sectional view taken along line VV in FIG. 4, and FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 2 to 6, the XX direction is referred to as the left-right direction, and the YY direction is referred to as the front-rear direction. In particular, the -X direction is leftward, the + X direction is rightward, the -Y direction is frontward, and the + Y direction is rearward. That's it.

  As shown in these drawings, the developing device 20 includes a pair of front and rear stirring and conveying members 30 (a first stirring and conveying member 301 at the front and a second stirring and conveying member 302 at the rear) in a box-shaped casing 21. A developing roller 40 that supplies a part of the toner circulated and conveyed in the casing 21 while being agitated by the first and second agitating and conveying members 301 and 302 toward the photosensitive drum 131 (FIG. 1) is internally provided. In addition, the rotating mechanism 50 for rotating the stirring and conveying member 30 is provided on the outer surface side of the housing 21.

  The casing 21 has a bottom plate 22 that is long in the left-right direction and whose left-right dimension is substantially equal to the length of the photosensitive drum 131, and a pair of side plates 23 in the left-right direction that are erected from left and right edges of the bottom plate 22. And a front plate 24 erected from the front edge of the bottom plate 22, and a top plate 25 (FIGS. 4 to 6) laid between the pair of side plates 23. From the upper edge portion of the front plate 24, a container support plate 241 formed in an elliptical shape in a side view so as to match the elliptical shape of the bottom plate of the toner container 19 extends forward, and the toner container 19 The developing device 20 is detachably mounted while being supported by the container support plate 241.

  The bottom plate 22 has an arcuate bottom plate 221 formed in an arc shape convex downward in a side view so as to correspond to the peripheral surface of the developing roller 40 at a rear portion, and forward from a front edge portion of the arcuate bottom plate 221. It consists of a flat bottom plate 222 extending toward the end. An agitating / conveying chamber V for agitating and conveying the toner surrounded by the pair of side plates 23, the front plate 24 and the top plate 25 is formed above the flat bottom plate 222.

  The flat bottom plate 222 is set to have a front-rear width dimension slightly longer than twice the short-side width dimension (front-rear width dimension) of the agitating and conveying member 30, thereby extending a pair of agitating and conveying members 30 extending in the left-right direction. Can be juxtaposed in the front-rear direction. A partition plate 26 is erected on the flat bottom plate 222 in the center in the front-rear direction, whereby the agitation transport chamber V is in front of the partition plate 26 and rearward of the partition plate 26. And a second agitating and conveying chamber V2.

  Passing openings 261 through which toner passes are respectively provided between the left and right edges of the partition plate 26 and the side plate 23, and the toner agitated and conveyed by the agitating and conveying member 30 passes through these passing openings 261. The first and second agitating / conveying chambers V1 and V2 can be circulated therethrough. Further, as shown in FIG. 4, a layer thickness regulating blade 251 for regulating the layer thickness of the toner is suspended from the position directly above the developing roller 40 on the top plate 25, and the lower edge of the layer thickness regulating blade 251 and the development are developed. A toner supply opening 21 b is formed between the peripheral surface of the roller 40. The upper and lower gap dimensions of the toner supply opening 21b are set by the layer thickness regulating blade 251, and thereby the layer thickness of the toner supplied from the developing roller 40 to the photosensitive drum 131 becomes a preset value.

  The agitating and conveying member 30 includes a centroid shaft (rotating shaft) 31 laid between the pair of side plates 23 in the first and second agitating and conveying chambers V1 and V2, and a centroid position passing through the centroid shaft 31. A plurality of stirring fins 32 to be fixed are provided.

  The center of gravity axis 31 is set to be slightly longer than the inner dimension between the pair of side plates 23, and extends between the side plates 23 in a state of passing through the pair of side plates 23. A rotation mechanism 50 is formed at one end of the barycentric shaft 31 penetrating the side plate 23 (the right end in the example shown in FIG. 2). Each end of the center of gravity shaft 31 is provided with a small-diameter tip 311 projecting concentrically in opposite directions.

  In order to support the rotation mechanism 50, the right side plate 23 is provided with a pair of support frame bodies 27 corresponding to the first and second stirring and conveying chambers V1 and V2, respectively. Each support frame 27 has a U-shape in a plan view, and is extended between a pair of projecting plates 271 in the front-rear direction projecting outward and between the leading edges of the projecting plates 271. It consists of a guide plate 272. An annular guide groove 53 described later is provided on the inner surface side of the guide plate 272. Then, the small-diameter tip portion 311 of the center of gravity shaft 31 that protrudes from the side plate 23 through the sub-circular hole 510 described later into the support frame 27 is fitted into the annular guide groove 53.

  The subcircular hole 510 is also provided in the left side plate 23. Further, only the guide plate 272 is fixed to the left side plate 23 in a state where the outer surface side covers the sub-circular hole 510. A small-diameter tip 311 on the left side of the center of gravity shaft 31 penetrating the subcircular hole 510 is fitted in the annular guide groove 53 of the left guide plate 272.

  In the present embodiment, the stirring fins 32 are set in the shape of a triangular Reuleaux. A plurality of stirring fins 32 having the triangular shape of the rouleau are continuously provided in a state where predetermined edges are joined to each other, thereby forming a spiral feeder 320 as shown in FIG. . One of the pair of agitating and conveying members 30 provided with such a spiral feeder 320 is attached to the first agitating and conveying chamber V1 as the first agitating and conveying member 301, and the other is attached to the second agitating and conveying chamber V2. The second stirring and conveying member 302 is used.

  Incidentally, in the present embodiment, the spiral feeder 320 formed by connecting a plurality of stirring fins 32 is spiral in a left-handed state.

  The characteristics of the Rouleau triangle will be described below with reference to FIGS. FIGS. 7 and 8 are explanatory diagrams for explaining the Reuleaux triangle T employed as the shape of the stirring fin 32. FIGS. 7A to 7F are reference of the Reuleaux triangle T. FIG. FIGS. 8A to 8F show a state in which the vertex Q is rotated counterclockwise by 150 ° from the reference position W to 150 °. FIGS. 8A to 8F show that the reference vertex Q of the Rouleau triangle T is 180 degrees from the reference position. A state rotated counterclockwise by 30 ° to 330 ° is shown with a state rotated counterclockwise as a starting point (FIG. 8A). FIG. 8G shows a subcircular shape formed by the circular locus of the center of gravity G when the Rouleau triangle T rotates within the regular tetragon S. FIG.

  The Reuleaux triangle T is formed by forming an arc corresponding to each side centered on each vertex, with the length of one side of the regular triangle indicated by the alternate long and short dash line in FIG. 7A as the radius. As shown in FIGS. 7 and 8 (A) to 8 (F), the Reuleaux triangle T has a vertex T and a side of a regular square S whose side is set to the length of one side of the regular triangle. The circular arc can be rotated while approaching each side of the regular square to a state close to sliding contact or contact. Hereinafter, such rotation is referred to as roulau rotation.

  Then, one vertex of the Reuleaux triangle T is set as a reference vertex Q, and first, the reference vertex Q is set to the midpoint position (reference position W) of the horizontal line above the regular square S as shown in FIG. ), And then continuously rotating the Rouleau triangle T by 30 ° counterclockwise with respect to the perpendicular L passing through the reference vertex Q, the center of gravity G of the Rouleau triangle T is shown in FIG. As shown in FIG. 8 (F), it is rotated by 90 ° around the center O of the regular square S in the clockwise direction (that is, in the direction opposite to the rotation direction of the triangle T of Rouleau).

  Accordingly, when the Reuleaux triangle T rotates once in the regular square S in the counterclockwise direction from the state shown in FIG. 7A (see FIG. 7 (A) to FIG. 8F through the states shown in FIG. When returning to the state of A), the center of gravity G of the Reuleaux triangle T turns around the center O of the regular square S three times in the clockwise direction.

  In FIGS. 7B to 7F and FIGS. 8A to 8F, the rotation angle from the reference position W of the reference vertex Q of the triangle T of the rouleau is displayed in degrees, and The number of rounds of the center of gravity G of the triangle T is shown in square brackets. In addition, the approximate locus of the center of gravity G is displayed as a spiral, making it easy to understand the number of turns.

  Incidentally, as shown in FIG. 8G, the locus of the center of gravity G of the Rouleau triangle T when the Rouleau triangle T rotates within the tetragon S is that the four corners are centered on the center O of the equilateral square S. Is a shape (hereinafter referred to as a subcircular shape K) having a part of a predetermined elliptical shape with a radius of curvature smaller than that of the inscribed circle.

  In the present invention, the Reuleaux triangle T exhibiting the above behavior in the regular square S is applied to the shape of the stirring fin 32, and the regular square S is the first and second stirring and conveying members 301, This is applied to 302 main first and second agitating and conveying chambers V1 and V2.

  Therefore, the periphery of the stirring fin 32 in the first stirring / conveying member 301 always has a flat bottom plate 222, a front plate 24, and In the second stirring and conveying member 302, the peripheral edge of the stirring fin 32 is always in sliding contact or contact with the flat plate bottom plate 222 and the partition plate 26. It will be close to a close state. Therefore, the toners located in the first and second stirring and conveying chambers V1 and V2 are always in the first and second stirring and conveying chambers V1 and V2 in a state where there is almost no blind spot due to the apex or arcuate edge of the stirring fin 32. Since the toner is scraped from the inner wall surface, it is possible to effectively avoid the occurrence of inconvenience that toner is accumulated in the first and second stirring and conveying chambers V1 and V2.

  Hereinafter, the rotation mechanism 50 will be described based on FIG. 9 with reference to other drawings as needed. FIG. 9 is a perspective view showing an embodiment of the rotation mechanism 50. The direction display by X and Y in FIG. 9 is the same as in FIG. 2 (X is the left-right direction (−X: leftward, + X: rightward), Y is the front-rear direction (−Y: forward, + Y: rearward). )).

  As shown in FIG. 9, the rotation mechanism 50 has sub-circular holes 510 (only the right-hand side is shown in FIG. 9) provided in the left-right direction so as to face the pair of side plates 23 of the housing 21. 2), the internal gear 51 formed on the inner peripheral surface of the sub-circular hole 510, and both end portions of the center of gravity shaft 31 of the stirring and conveying member 30 so as to mesh with each internal gear 51. A pair of orbiting gears 52 that are concentrically and externally fitted so as to be integrally rotatable (only the right one is shown in FIG. 9; see the left orbiting gear 52 in FIG. 2) and the opposing surfaces of the pair of guide plates 272 The driving force from the pair of left and right annular guide grooves 53 that are respectively recessed and are guided by the end portions of the center of gravity shaft 31 and the driving source 60 provided on the printer body 11 side is transmitted. Driving force transmitted gear 54.

  Each of the internal gears 51 of the stirring fins 32 is in a state in which the stirring fins 32 are rotated to the state shown in FIG. 7 and FIG. 8 while the stirring fins 32 are close to the inner wall surface of the stirring conveyance chamber V. A trajectory larger than the trajectory corresponding to the subcircular shape K shown in FIG. 8G of the center of gravity shaft 31 (specifically, a trajectory larger than the trajectory of the axial center of the center of gravity shaft 31 by the radius of the rotating gear 52). ).

  The annular guide groove 53 has a center of gravity in a state in which the roulette is rotated while the stirring fin 32 having a triangular shape of the roule is in close contact with the inner wall surface in the stirring transport chamber V to a state close to sliding contact or contact. The shaft 31 is recessed so as to follow a circular locus of the subcircular shape K of the axis of the shaft 31 (see FIG. 2).

  Therefore, when the driving force from the driving source 60 is transmitted to the center of gravity shaft 31 through the driving force transmitted gear 54 and the center of gravity shaft 31 rotates about the axis, this rotation is applied to the internal gear 51. It is transmitted to the meshing gear 52. As a result, when the orbiting gear 52 rotates around the center of gravity axis 31, the orbiting gear 52 moves along the internal gear 51 due to meshing with the internal gear 51. The distal end portion 311 is fitted into the annular guide groove 53 and guided to the annular guide groove 53.

  As a result, the revolving gear 52 revolves along the sub-circular hole 510 while continuing to mesh with the internal gear 51 without being disengaged from the internal gear 51. As a result, the revolving gear 52 is integrated with the revolving gear 52 via the center of gravity shaft 31. The agitation fin 32 rotates the roulau along the inner wall surface of the agitation conveyance chamber V.

  On the other hand, the drive source 60 includes a drive motor 61 mounted vertically on a frame (not shown) of the printer main body 11, and a worm 62 externally fitted to the drive shaft 611 of the drive motor 61 so as to be integrally rotatable. It has. The drive motor 61 has a bracket 612 projecting downward from its lower end, while the frame of the printer body 11 extends in the left-right direction at a position directly below the drive force transmitted gear 54. A support shaft 63 is provided.

  The drive motor 61 is pivotally supported around the support shaft 63 by the bracket 612 being fitted on the support shaft 63 so as to be rotatable. The support shaft 63 is set at an installation position so that the worm 62 meshes with the drive force transmitted gear 54 in a state where the drive motor 61 is erected from the support shaft 63. The length of the drive shaft 611 is set so that the drive motor 61 protrudes slightly upward from the support frame 27 with the drive motor 61 standing from the support shaft 63.

  Further, between the upper edge portions of the pair of projecting plates 271 of the support frame body 27, the drive shaft 611 is prevented from laterally swinging in the left-right direction, and the lateral swing is guided to move in the front-rear direction. A prevention plate 64 is installed. The lateral shake prevention plate 64 is provided with a guide long hole 641 extending in the front-rear direction at the center in the circumferential direction. The worm 62 has a fitting insertion shaft 621 having a smaller diameter than the worm 62 concentrically provided at the upper end of the drive shaft 611, and the fitting insertion shaft 621 passes through the guide long hole 641 of the lateral shake prevention plate 64. By doing so, it can be rotated forward and backward around the support shaft 63 in the front-rear direction in a state that is prevented if the sideways swing in the left-right direction.

  Further, a locking projection piece 642 protrudes from the front end portion of the lateral shake prevention plate 64, and an extended biasing force is provided between the locking projection piece 642 and the fitting insertion shaft 621 of the drive shaft 611. A coil spring 65 as a member is stretched. As a result, the worm 62 is always urged toward the driving force transmitted gear 54 via the driving shaft 611, so that the driving force transmitted gear 54 is annularly guided via the small-diameter tip portion 311 of the center of gravity shaft 31. Even if it circulates along the groove 53, the meshing state of the worm 62 with the driving force transmitted gear 54 is ensured.

  In order to prevent the toner filled in the first and second agitating / conveying chambers V1 and V2 in which the agitating fin 32 rotates the roulu by the drive of the drive motor 61 from leaking to the outside from the subcircular hole 510. In addition, in this embodiment, a leakage prevention cover 70 as shown in FIGS. 2 and 6 is interposed between the side plate 23 and the center of gravity shaft 31.

  The leakage prevention cover 70 includes a bellows member 71 formed in a funnel shape made of a flexible material such as a predetermined soft synthetic resin or rubber, and a mounting ring 72 provided at a tapered tip of the bellows member 71. A flange portion 73 provided on the opposite side of the mounting ring 72 of the bellows member 71 is provided.

  The bellows member 71 is set so that its inner diameter can be fitted on the center of gravity shaft 31 in a sliding state. Further, the flange portion 73 is set in a square shape whose one side is set so that the sub-circular hole 510 can be closed.

  The mounting ring 72 is fitted on the center of gravity shaft 31 before the rounding gear 52 and the driving force transmitted gear 54 are fitted on the center of gravity shaft 31, and is mounted between the rounding gear 52 and the stirring fin 32 at the end. The Further, the flange portion 73 is fixed to the side plate 23 by screwing or the like so that the bellows member 71 closes the subcircular hole 510 in a state where the mounting ring 72 is externally fitted to the center of gravity shaft 31.

  According to the leakage prevention cover 70, the leakage of the toner from the sub-circular hole 510 is prevented by the bellows member 71, and the elasticity of the bellows member 71 is maintained even when the center of gravity shaft 31 rotates while being guided by the annular guide groove 53. The rotation is absorbed by the deformation.

  As described above in detail, the developing device 20 according to the present invention supplies the toner filled in the casing 21 to the photosensitive drum 131, and the toner is supplied to the photosensitive drum 131 in the casing 21. An agitating / conveying member 30 that conveys while agitating while rotating so as to be supplied to the toner is provided, and the agitating / conveying member 30 is a portion that is substantially in the shape of a polygonal ruler when viewed from a direction orthogonal to the toner conveying direction. (In this embodiment, the stirring fin 32 is provided at least in part). Therefore, the stirring and conveying member 30 has a radius of curvature of an arc centered on the apex of the Rouleau polygon (in this embodiment, the Rouleau triangle). By rotating within a predetermined frame (in this embodiment, the inner wall surfaces of the first and second agitating and conveying chambers V1 and V2), which is one side, for example, the center of gravity of the Rouleau polygon is obtained. Several times the angular velocity of the angular velocity of the body portion toward the pair direction (e.g., three times if the polygon Reuleaux is triangular, 5-fold in the case of a pentagon, in the case of heptagonal 7 times, etc.) orbiting at.

  Therefore, by rotating the stirring fins 32 in the first and second stirring and conveying chambers V1 and V2, the toner in the first and second stirring and conveying chambers V1 and V2 is in the vicinity of the position of the center of gravity of the stirring fins 32. Since forces in opposite directions act between the object and the surrounding objects, the toner is efficiently agitated, so that the position of the conventional agitating and conveying member is fixed like a normal spiral feeder. The toner in the housing 21 of the developing device can be more reliably agitated as compared with the one rotating around the axis.

  Further, when the agitating / conveying member 30 is rotated in the first and second agitating / conveying chambers V1 and V2 of the housing 21, the triangular vertexes of the rouleau in the agitating / conveying member 30 are changed to the first and second agitating / conveying chambers. Since the toner can be in a state of being very close to the corners of V1 and V2, toner deposited on the corners in the casing 21 as compared with the conventional stirring and conveying member 30 rotating around the fixed axis. The amount of can be reduced.

  Further, when the agitating and conveying member 30 is rotated in the square first and second agitating and conveying chambers V 1 and V 2, the agitating fin 32 is rotated every predetermined angle corresponding to the number of corner portions formed in the agitating fin 32. Since the direction of the force applied to the toner located in the vicinity of the toner rapidly changes (that is, there is a displacement point), this also causes the inside of the casing 21 of the developing device as compared with the conventional stirring fin 32 where there is no displacement point. This toner can be sufficiently stirred.

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

  (1) In the above embodiment, the printer 10 has been described as an example of the image forming apparatus to which the developing device 20 according to the present invention is applied. However, the image forming apparatus is limited to the printer 10. Instead, it may be a copying machine or a facsimile machine.

  (2) In the above embodiment, two chambers (first and second agitating / conveying chambers V1 and V2) are adopted as the agitating / conveying chamber V. However, there may be one chamber or three or more chambers. May be.

  (3) In the above embodiment, the agitating and conveying member 30 provided with the agitating fins 32 is applied. However, instead of this, even if a cylindrical body that exhibits a Rouleau polygonal shape in end view is adopted. Good. In this case, if a spiral recess is formed on the surface of the cylindrical body, the toner in the stirring and transporting chamber V is moved along the spiral recess by rotating the cylindrical body in the stirring and transporting chamber V. And the corners of the polygonal cylindrical body of the roulau are in close contact with the wall surface of the agitating / conveying chamber V so as to be close to the state of sliding contact or contact, and the toner in the corners of the agitating / conveying chamber V is scraped. Occurrence of inconvenience that toner accumulates in the agitation transport chamber V is prevented.

It is explanatory drawing of the side sectional view which shows one Embodiment of the printer with which the image development apparatus concerning this invention was applied. 1 is an exploded perspective view showing an embodiment of an internal structure of a developing device according to the present invention. It is an assembly perspective view of the internal structure shown in FIG. FIG. 3 is an assembled perspective view of an external appearance of the developing device. It is the VV sectional view taken on the line of FIG. It is the VI-VI sectional view taken on the line of FIG. It is explanatory drawing for demonstrating the Rouleau triangle, (A)-(F) has each shown the state which the reference | standard vertex of the Rouleau triangle rotated to 150 degrees by 30 degrees counterclockwise from the reference position. . It is explanatory drawing for demonstrating the Rouleau triangle, (A)-(F) is 30 degrees counterclockwise from the state where the reference vertex of the Rouleau triangle is rotated 180 degrees counterclockwise from the reference position. Each shows a state rotated to 330 °. Further, (G) shows a subcircular shape formed by a circular locus of the center of gravity when the Rouleau triangle rotates within a regular square. It is a perspective view which shows one Embodiment of a rotation mechanism.

Explanation of symbols

10 Printer (image forming device)
DESCRIPTION OF SYMBOLS 11 Printer main body 12 Paper storage part 121 Paper cassette 122 Pickup roller 123 Paper feed conveyance path 124 Registration roller pair 13 Image formation part 131 Photosensitive drum (image carrier)
132 Charger 133 Exposure Device 134 Transfer Roller 135 Cleaning Device 14 Fixing Unit 141 Fixing Roller 142 Pressure Roller 143 Outlet Transport Path 15 Outlet 151 Outlet Tray 19 Toner Container 20 Developing Device 21 Housing 21a Receiving Opening 21b Toner Supply Opening 22 Bottom plate 221 Arc shaped bottom plate 222 Flat bottom plate 23 Side plate 24 Front plate 241 Container support plate 251 Layer thickness regulating blade 25 Top plate 26 Partition plate 261 Passing opening 27 Support frame 271 Projection plate 272 Guide plate 30 Stirring and conveying member 301 First agitating and conveying member 302 Second agitating and conveying member 31 Center of gravity axis (rotating axis)
311 Small-diameter tip 32 Stirring fin 320 Spiral feeder 40 Developing roller 50 Rotating mechanism 51 Internal gear 510 Sub-circular hole 52 Circulating gear 53 Annular guide groove 54 Driving force transmitted gear 60 Driving source 61 Driving motor 611 Driving shaft 612 Bracket 62 Warm 63 Support shaft 64 Prevention plate 641 Guide elongated hole 642 Locking protrusion 65 Coil spring 70 Leakage prevention cover 71 Bellows member 72 Mounting ring 73 Flange part V Stirring conveyance chamber V1 First agitation conveyance chamber V2 Second agitation conveyance chamber G Center of gravity K Subcircular shape L Perpendicular N Nip part O Center P Paper P1 Paper bundle Q Reference vertex S Regular square T Triangle W Reference position

Claims (4)

A developing device for supplying a developer filled in a predetermined housing to an image carrier,
In the casing, a stirring and conveying member that conveys the developer while rotating to supply the developer to the image carrier is provided,
The stirring conveying member, possess at least a portion of the moiety that is the polygonal shape of substantially Reuleaux viewed from a direction perpendicular to the conveying direction of the developer,
The housing includes an agitating and conveying chamber provided with a wall surface that is close to a state where each vertex of the polygon of the substantially roulau is in sliding contact or close to contact according to the rotation of the agitating member,
The agitating and conveying chamber has end walls facing each other, and the agitating and conveying member includes a rotating shaft constructed between the pair of end walls, and a plurality of sheets fixed to be concentrically and integrally rotatable with the rotating shaft. And a stirring fin, wherein the stirring fin is a polygonal portion of the substantially rouleau . A pair of the agitating and conveying members are arranged in parallel to each other,
The casing is provided with a partition plate that is close to a state in which corner portions of the stirring fins are in sliding contact or close to contact between the pair of stirring transport chambers to which the stirring transport members are mounted.
At both ends of the partition plate, a passage opening for allowing the developer to pass between the pair of agitating and conveying chambers is provided,
The developing device according to claim 1, wherein a supply opening for supplying developer to the image carrier is provided on a surface of the housing facing the image carrier . The developing device according to claim 1 or 2, characterized in that the rotating mechanism for rotating the stirring carrying member on one side of the end wall facing each other are provided. The polygon developing device according to any one of claims 1 to 3, characterized in that it is triangular.

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