JP2013186138A - Development device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an unevenness of a developer layer on a developer holding body arising from a rotation of a supply member.SOLUTION: A development device 100 comprises: a development sleeve 106B; a magnet roll 106A; a trimmer 108 that regulates a thickness of a layer of developer G; a first auger 109 that supplies the developer G to the development sleeve 106B; and a shield block 110. The shield block 110 is arranged across tangents L1 and L2 and a line segment L3 which are drawn through a point A denoting a tip center of the trimmer 108, a point B denoting a tip center of pick-up pole S3 and a point C denoting a rotary shaft center of the first auger 109. In the development device 100, an acting force by a rotation of the first auger 109 with respect to the developer G entering between the development sleeve 106B and the trimmer 108 is blocked by the shield block 110. Thereby, the unevenness of the developer layer on the development sleeve 106B can be suppressed.

Description

  The present invention relates to a developing device and an image forming apparatus.

  The image forming apparatus of Patent Document 1 is formed adjacent to the developing sleeve, the developer storing portion in which the stored developer is held and conveyed by the developing sleeve as the developing sleeve rotates, and the developer storing portion. A supply conveyance path that conveys the developer in the axial direction of the developing sleeve while supplying the developer to the developer storage section through the opening, and the developer that has reached the downstream end in the conveyance direction of the supply conveyance path in the supply conveyance path A developing device including a circulation conveyance path that conveys to the upstream end in the conveyance direction. The developing device includes a shielding wall that forms the upper end of the supply opening and shields between the supply conveyance path and the developer storage portion above the upper end of the supply opening.

JP 2011-017857 A

  An object of the present invention is to obtain a developing device and an image forming apparatus that can suppress unevenness of a developer layer on a developer holding member caused by rotation of a supply member.

  A developing device according to claim 1 of the present invention is formed in a cylindrical shape, holds a developer containing magnetic particles on an outer peripheral surface, rotates in a circumferential direction, and is provided inside the developer holder. A magnetic force generating section in which a plurality of magnetic poles are arranged along the circumferential direction of the developer holder, the magnetic poles including an attracting pole that attracts the developer and a layer forming pole for forming a developer layer; A developer regulating member disposed opposite to the layer forming electrode via the developer holding body to regulate the thickness of the developer layer on the outer peripheral surface of the developer holding body, and in the rotation direction of the developer holding body The developer holding member is disposed on the upstream side of the developer regulating member so as to face the developer holding member, and the rotation axis direction of the developer holding member is aligned, and the spiral blades are rotated to move the developer in the rotation axis direction. A supply member that conveys the developer and supplies the developer to the developer holder; The tip of the developer regulating member that is integrated with a housing that accommodates the developer supplied by the member and faces the developer holder of the developer regulating member when viewed in the direction of the rotation axis is point A, the attracting pole. The center of the tip of the developer holding member is point B, and the center of the rotation axis of the supply member is point C. Of the tangent lines drawn from the point A to the outer periphery of the rotation locus of the wing, A line segment connecting the point A and the point C with the tangent line L1 on the near side, the tangent line L2 on the side closer to the developer regulating member among the tangent lines drawn from the point B to the outer periphery of the rotation locus of the blade, And a blocking member disposed across L3.

  In the developing device according to a second aspect of the present invention, the blocking member is a single member or the developer regulating member, and is farther from the developer holding body than the tip of the developer regulating member, and is on the developer holding body side. A space that opens to the center is formed.

  In the developing device according to a third aspect of the present invention, the developer regulating member is disposed below the developer holding member, and the developer has a height up to a height equal to or higher than the upper end of the blocking member in the housing. Are to be stored.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus according to the first aspect, wherein the latent image is held on the outer peripheral surface, and the latent image is developed with a developer to form a developer image. The developing device according to claim 1, and a transfer unit that transfers the developer image developed by the developing device to a recording medium.

  According to the first aspect of the present invention, the unevenness of the developer layer on the developer holding member caused by the rotation of the supply member can be suppressed as compared with the configuration having no blocking member.

  According to the second aspect of the present invention, the amount of developer held by the developer holding body over time is longer than that of the configuration having a blocking member whose distance from the developer holding body is about the same as the developer regulating member. The amount of fluctuation can be reduced.

  The invention according to claim 3 suppresses a decrease in the amount of developer supplied to the periphery of the attracting pole as compared with the configuration in which the developer is stored up to a height lower than the upper end of the blocking member in the housing. it can.

  According to the fourth aspect of the present invention, image unevenness in the width direction intersecting with the conveyance direction of the recording medium can be suppressed as compared with the configuration without the developing device according to the first to third aspects.

1 is an overall configuration diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a partial configuration diagram illustrating a configuration around an intermediate transfer belt of the image forming apparatus according to the first exemplary embodiment of the present invention. 1 is a longitudinal sectional view of a developing device according to a first embodiment of the present invention. 1 is a cross-sectional view of a developing device according to a first embodiment of the present invention. It is explanatory drawing which shows arrangement | positioning of the interruption | blocking block which concerns on 1st Embodiment of this invention. (A) It is a schematic diagram which shows the force produced by rotation of the 1st auger which concerns on 1st Embodiment of this invention. (B) It is a schematic diagram which shows the state which force acts on the developing agent between a developing sleeve and an auger by rotation of the 1st auger concerning 1st Embodiment of this invention. It is explanatory drawing which shows the effect | action of the interruption | blocking block which concerns on 1st Embodiment of this invention. (A) It is explanatory drawing which shows the state in which a developer is conveyed by the 1st auger which concerns on 1st Embodiment of this invention. (B) It is a schematic diagram which shows the state of the developer layer in the axial direction of the developing sleeve outer peripheral surface which concerns on 1st Embodiment of this invention. (C) is a schematic diagram showing the state of the developer layer in the axial direction of the outer peripheral surface of the developing sleeve of the first comparative example. (A) It is a schematic diagram which shows the flow of the developer between the interruption | blocking block which concerns on 1st Embodiment of this invention, and a developing sleeve. (B) It is a schematic diagram which shows the flow of the developer between the interruption | blocking block of a 2nd comparative example, and the image development sleeve. 5 is a graph showing the amount of developer per unit area on the developing sleeve with respect to the distance from the trimmer tip at the end of the blocking block according to the first embodiment of the present invention. It is a longitudinal cross-sectional view of the developing device which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows the effect | action of the interruption | blocking block which concerns on 2nd Embodiment of this invention.

(First embodiment)
An example of the developing device and the image forming apparatus according to the first embodiment of the present invention will be described.

(overall structure)
FIG. 1 shows an image forming apparatus 10 as an example of the first embodiment. The image forming apparatus 10 includes a sheet storage unit 12 that stores a recording sheet P as an example of a recording medium and a sheet storage unit 12 on the sheet storage unit 12 from the lower side to the upper side in the vertical direction (the arrow Y direction in the drawing). And an image forming unit 14 that forms an image on the recording paper P that is provided and supplied from the paper storage unit 12. In the following description, the vertical direction of the image forming apparatus 10 is the Y direction, the horizontal direction is the X direction, the depth direction orthogonal to the X direction and the Y direction is the + Z direction, and the direction opposite to the + Z direction is the −Z direction. Describe. When there is no need to distinguish the + and − directions, they are simply described as the Z direction. In addition, the description of “left” and “right” represents left and right when the image forming apparatus 10 is viewed from the front (corresponding to the left and right in the figure).

  Further, the image forming apparatus 10 includes a discharge unit 16 that is integrally provided on the upper side of the image forming unit 14 and discharges the recording paper P on which the image is formed, and a document reading that is provided on the discharge unit 16 and reads the read document GE. And a control unit 20 that is provided in the image forming unit 14 and controls the operation of each unit of the image forming apparatus 10.

  In the paper storage unit 12, a first storage unit 22, a second storage unit 24, and a third storage unit 26 that store recording papers P of different sizes are provided side by side in the Y direction. The first storage unit 22, the second storage unit 24, and the third storage unit 26 send out the stored recording paper P to a conveyance path 30 (illustrated by a two-dot chain line) provided in the image forming apparatus 10. A roll 32 is provided. A plurality of pairs of transport rolls 34 and transport rolls 36 for transporting the recording paper P one by one are provided on the downstream side of the feed path 32 in the transport path 30. Further, the recording paper P is transported downstream of the transport roll 36 in the transport direction of the recording paper P and in the image forming section 14, the recording paper P is stopped once and the secondary transfer section 37 is determined at a predetermined timing. An alignment roll 38 to be fed out (details will be described later) is provided.

  The image forming unit 14 includes a housing 16A that is an apparatus main body. In the housing 16 </ b> A, the upper left portion of the image forming unit 14 protrudes above the upper center portion and the upper right portion in a front view of the image forming apparatus 10. The left end portion and the back side of the document reading unit 18 are coupled to the upper end and the back side of the discharge unit 16. As a result, the image forming apparatus 10 has a discharge area 19 surrounded by the upper surface of the image forming unit 14, the lower surface of the document reading unit 18, and the right side surface of the discharge unit 16. In the discharge area 19, the recording paper P is discharged and stacked from the discharge unit 16.

  Further, a fixing device 80 is provided in the image forming unit 14 on the downstream side of the secondary transfer unit 37 in the conveyance path 30. The fixing device 80 includes a fixing roll 82 that heats the developer (toner) on the recording paper P, and a pressure roll 84 that presses the recording paper P toward the fixing roll 82. When passing through the contact portion between the fixing roll 82 and the pressure roll 84, the toner is melted and solidified, and the toner image TA (see FIG. 2) is fixed on the recording paper P.

  As shown in FIGS. 1 and 2, in the center of the image forming unit 14, toners on the recording paper P are combined with toners of black (K), cyan (C), magenta (M), and yellow (Y). An image forming unit 40 for forming an image (developer image) is provided.

  In the image forming unit 40, photoconductors 42K, 42C, 42M, and 42Y as an example of an image holding member that holds a latent image are black (K), cyan (C), magenta (M), and yellow (Y) colors. Are provided corresponding to the toners. In the following description, when it is necessary to distinguish between K, C, M, and Y, an alphabetical letter K, C, M, or Y is added after the numeral, and the same configuration is used for K. , C, M, and Y are omitted when it is not necessary to distinguish them.

  As shown in FIG. 2, the photoconductors 42K, 42C, 42M, and 42Y are arranged in this order toward the right side in the figure, and rotate in the direction of the arrow b (counterclockwise direction in the figure). Yes. Further, around each photoconductor 42, a charging roll 46, a developing device 100, an intermediate transfer belt 48 and a primary transfer roll 52 as an example of a transfer unit, and a cleaning roll 54 are sequentially provided along the arrow b direction. Is provided.

  As an example, the charging roll 46 has a configuration in which a plurality of layers (all not shown) including a conductive elastic layer, an intermediate layer, and a surface resin layer are formed around a shaft portion made of stainless steel. The charging roll 46 is rotatably provided with a shaft so that the outer peripheral surface thereof is in contact with the surface layer of the photoconductor 42 and is driven by a voltage applied from a voltage application unit (not shown). The outer peripheral surface of the photoconductor 42 is charged by the generated discharge.

  Light L (LK, LC, LM, LY) corresponding to each toner color is exposed at a position between the charging roll 46 and the developing device 100 on the outer peripheral surface of the photoconductor 42, which will be described later (see FIG. 1). ) Is irradiated (exposed).

  As shown in FIG. 1, the exposure apparatus 60 includes a semiconductor laser and an f-θ lens (not shown), polygon mirrors 62A and 62B, an imaging lens (not shown), and a plurality of mirrors 64. The exposure device 60 deflects and scans the laser light emitted from the semiconductor laser based on the image signal by the polygon mirrors 62A and 62B, and irradiates the outer peripheral surface of the photoreceptor 42 charged by the charging roll 46 (see FIG. 2). (Exposure) to form an electrostatic latent image. The photoconductor 42 holds the electrostatic latent image on the outer peripheral surface. The exposure device 66 is not limited to a method of scanning laser light with a polygon mirror, but may be an LED (Light Emitting Diode) method.

  As shown in FIG. 2, a developing device 100 that forms a developer image on the photoconductor 42 is provided at a position facing the photoconductor 42 on the downstream side of the exposure position by the light L in the arrow b direction. Details of the developing device 100 will be described later.

  The intermediate transfer belt 48 is formed in an endless shape, and includes a belt conveyance roll 72 provided in the secondary transfer unit 37, a belt conveyance roll 74 provided obliquely above the belt conveyance roll 72, and an X direction. Wrapped around a driving roll 76 provided on the opposite side of the belt conveying roll 74 and driven by a motor (not shown) and a belt conveying roll 78 provided diagonally to the left of the driving roll 76, the direction of arrow a It is supported so as to be able to move around (clockwise in the figure). The outer peripheral surface of the intermediate transfer belt 48 is a transfer surface to which a toner image TA as an example of a developer image is transferred, and the transfer surface from the belt conveyance roll 78 to the belt conveyance roll 72 of the intermediate transfer belt 48 is photosensitive. The outer peripheral surfaces of the bodies 42K, 42C, 42M, and 42Y are in contact.

  A primary transfer roll 52 (52K, 52C, 52M, 52Y) is provided on the opposite side of the photoreceptors 42K, 42C, 42M, 42Y across the intermediate transfer belt 48. The primary transfer roll 52 is in contact with the inner peripheral surface of the intermediate transfer belt 48. The primary transfer roll 52 applies a voltage from a voltage application unit (not shown), thereby intermediate transfer of the toner image held on the outer peripheral surface of the photoconductor 42 due to a potential difference from the grounded photoconductor 42. Primary transfer is performed on the transfer surface of the belt 48. As a result, when the intermediate transfer belt 48 is revolving, the toner images are transferred onto the intermediate transfer belt 48 so as to form a toner image TA.

  As an example, the cleaning roll 54 is configured by a brush roll in contact with the outer peripheral surface of the photoreceptor 42. The cleaning roll 54 scrapes off toner remaining on the outer peripheral surface of the photoreceptor 42 and collects it in the cleaning unit (not shown). A cleaning member (not shown) for cleaning the toner remaining on the transfer surface of the intermediate transfer belt 48 after the secondary transfer is provided on the opposite side of the intermediate transfer belt 48 from the drive roll 76 side. It has been.

  On the other hand, the secondary transfer unit 37 is an example of a belt conveying roll 72 around which the intermediate transfer belt 48 is wound, and a transfer unit provided on the opposite side of the intermediate transfer belt 48 from the belt conveying roll 72 side. A secondary transfer roll 79 is included. A voltage is applied to the belt conveyance roll 72 or the secondary transfer roll 79 from a voltage application unit (not shown). Due to the potential difference between the belt conveyance roll 72 and the secondary transfer roll 79, an intermediate transfer belt is provided. The toner image TA on 48 is secondarily transferred onto the recording paper P being transported in the transport path 30.

  As shown in FIG. 1, on the upper side of the intermediate transfer belt 48 of the image forming unit 14, a toner cartridge 86K that stores black (K), cyan (C), magenta (M), and yellow (Y) toners. 86C, 86M, and 86Y are interchangeably provided. Further, on the downstream side of the fixing device 80 in the transport path 30 in the discharge unit 16, a transport roll 87 for transporting the recording paper P after fixing, and the recording paper P transported by the transport roll 87 to the discharge area 19. A discharge roll 88 for discharging is provided.

  On the other hand, the document reading unit 18 includes a document transport device 90 that automatically transports the read document GE one by one, a platen glass 92 that is arranged below the document transport device 90 and on which one read document GE is placed, and a document There is provided an original reading device 94 for reading the read original GE conveyed by the conveying device 90 or the read original GE placed on the platen glass 92.

  The document conveyance device 90 has an automatic conveyance path 96 in which a plurality of rolls including a delivery roll 91, a pair of conveyance rolls 93, and a registration roll 95 are arranged. The recording paper P is arranged so as to pass over the platen glass 92.

  The document reading device 94 reads the read document GE by receiving the reflected light LT of the light irradiated from the lamp 97 onto the document surface of the read document GE by the light receiving unit 98. Further, the document reading device 94 reads the read document GE conveyed by the document conveying device 90 while being stationary at the lower left end portion of the platen glass 92, or is placed on the platen glass 92 while moving in the X direction. A read original GE is read.

  Next, an image forming process in the image forming apparatus 10 will be described.

  As shown in FIG. 1, when the image forming apparatus 10 operates, image data of each color of black (K), cyan (C), magenta (M), and yellow (Y) is supplied from an image processing apparatus (not shown) or from the outside. Is output to the exposure apparatus 60. Subsequently, the light L (LK, LC, LM, LY) emitted according to the image data from the exposure device 60 exposes the outer peripheral surface (surface) of the photosensitive member 42 charged by the charging roll 46, and each photosensitive member is exposed. An electrostatic latent image corresponding to the image data of each color is formed on the surface of the body 42. Further, the electrostatic latent image formed on the surface of each photoconductor 42 is developed as a toner image by each developing device 100. The toner images on the surface of the respective photoreceptors 42 are sequentially sequentially transferred to the intermediate transfer belt 48 by the primary transfer roll 52 (see FIG. 2).

  On the other hand, the recording paper P sent out from the paper storage unit 12 and conveyed through the conveyance path 30 is aligned with the multiple transfer of each toner image onto the intermediate transfer belt 48 by the alignment roll 38, and the secondary transfer unit. It is conveyed to 37. The toner image that has been multiplex-transferred onto the intermediate transfer belt 48 is secondarily transferred by the secondary transfer roll 79 onto the recording paper P that has been conveyed to the secondary transfer portion 37.

  Subsequently, the recording paper P onto which the toner image has been transferred is conveyed to the fixing device 80. In the fixing device 80, the toner image is fixed on the recording paper P by being heated and pressed by the fixing roll 82 and the pressure roll 84. Further, the recording paper P on which the toner image is fixed is discharged from the discharge unit 16 to the discharge region 19.

(Main part configuration)
Next, the developing device 100 will be described.

  FIG. 3 shows the developing device 100. Since the developing devices 100K, 100C, 100M, and 100Y have the same configuration except for the toner in the developer to be used, the developing device 100 will be described without distinguishing K, C, M, and Y.

  The developing device 100 includes a housing 102 as an example of a housing in which the developer G is stored, a developing roll 106, and a developer regulation that regulates the thickness of the developer G layer held on the outer peripheral surface of the developing roll 106. A trimmer 108 as an example of a member, a first auger 109 as an example of a supply member that supplies the developer G to the developing roll 106, a second auger 111, and a blocking block 110 as an example of a blocking member. doing.

  As an example, the developer G is composed of a two-component developer including a toner T that is negatively charged and a magnetic carrier CA that is an example of magnetic particles that are positively charged. The developer G is stored in the housing 102 to a height equal to or higher than the upper end portion 110A (see FIG. 5) of the blocking block 110, which will be described in detail later.

  The housing 102 includes a container main body 103 and a cover member 104 that closes an upper portion of the container main body 103. The housing 102 includes a developing roll chamber 122 in which the developing roll 106 is accommodated, a first stirring chamber 123 provided below the developing roll chamber 122, and a second stirring chamber 124 adjacent to the first stirring chamber 123. And have.

  The container body 103 has a bottom wall 103A that is curved at two locations in the X direction so as to protrude downward, a flat portion 103B formed at the left end of the bottom wall 103A, and a right end of the bottom wall 103A. The side wall 103 </ b> C is formed, and the partition wall 103 </ b> D that stands upright at the center of the bottom wall 103 </ b> A and separates the first stirring chamber 123 and the second stirring chamber 124.

  The cover member 104 includes an upper wall 104A disposed on the second stirring chamber 124, an inclined wall 104B extending obliquely leftward from the left end of the upper wall 104A and covering the developing roll chamber 122, and an upper end of the inclined wall 104B. It has a curved wall 104C that is continuously curved, and a fitting portion 104D that extends downward from the end of the upper wall 104A and fits into the container body 103.

  FIG. 4 shows a cross section of the developing device 100. In FIG. 4, the developing roll 106 and the first auger 109 and the second auger 111 are shown on the same plane to explain the developing roll 106, but in reality, the developing roll 106 is better as shown in FIG. 3. Compared to the first auger 109 and the second auger 111, the auger 109 is disposed on the upper side in the Y direction. Further, in FIG. 4, the illustration of the blocking block 110 (see FIG. 3) is omitted.

  As shown in FIG. 4, support walls for supporting a shaft 106 </ b> C projecting outward in the + Z direction from both ends of a magnet roll 106 </ b> A (described later) are positioned at both ends in the axial direction (+ Z direction) of the developing roll 106 in the container body 103. 103E and 103F are formed. Further, in the container main body 103, the lengths of the first stirring chamber 123 and the second stirring chamber 124 in the + Z direction are longer than the interval between the support walls 103E and 103F, and a protruding portion 126 is formed. A wall portion (not shown) is connected between the support walls 103E and 103F on the lower side of the developing roll 106, and a trimmer 108 (see FIG. 3) is fixed to the wall portion with a screw 128 (see FIG. 3). ing.

  In the partition wall 103D, a first inlet 132 penetrating in the X direction is formed near the end in the −Z direction, and a second inlet 133 penetrating in the X direction is formed at the end in the + Z direction. As a result, when the first auger 109 and the second auger 111 rotate, the developer G circulates in the arrow K direction through the first inlet 132 and the second inlet 133.

  In addition, a developer discharge port 134 for discharging the developer G from the developing device 100 is formed below the first stirring chamber 123 in the protruding portion 126. A developer replenishing port 136 for replenishing new developer G into the developing device 100 is formed above the second stirring chamber 124 in the protruding portion 126. The developer supply port 136 is disposed in the −Z direction with respect to the first inlet 132 and is partitioned by the partition wall 103D, so that the newly supplied developer G is immediately supplied to the developer discharge port 134. Will not be discharged from.

  As shown in FIGS. 3 and 4, the developing roll 106 is formed in a cylindrical shape with a magnet roll 106 </ b> A as an example of a magnetic force generation unit that is formed in a columnar shape and fixedly supported on the container main body 103 via a shaft 106 </ b> C. And a developing sleeve 106B as an example of a developer holder that is rotatably supported outside the magnet roll 106A. That is, the magnet roll 106A is disposed inside the developing sleeve 106B.

  As shown in FIG. 3, the magnet roll 106A is provided with a plurality of magnetic poles along the outer peripheral surface (circumferential direction). Specifically, when viewed in the axial direction of the shaft 106C, the magnet roll 106A is close to the first auger 109. A pickup pole S3, a layer forming pole N2, a developing pole S1, a transport pole N1, and a pick-off pole S2 are provided as examples of the attracting pole in the clockwise direction from the lower side. Although magnetic field lines are generated from the transport pole N1 toward the development pole S1 and the pick-off pole S2, and from the layer formation pole N2 toward the development pole S1 and the pickup pole S3, they are not shown.

  Here, in the following description, when the magnet roll 106A is viewed in the axial direction, the position of each magnetic pole will be described assuming that the upper position is 12:00 and the lower position is 6 o'clock. As an example, the pickup pole S3 is arranged in the 4 o'clock direction, and attracts the developer G and holds it on the outer peripheral surface of the developing sleeve 106B. The layer forming pole N2 is disposed in the 7 o'clock direction so as to face the front end of the trimmer 108, and holds the plurality of magnetic carriers CA on the outer peripheral surface of the developing sleeve 106B in a state where the plurality of magnetic carriers CA are raised. Note that the magnetic force of the layer forming pole N2 in the present embodiment is lower (set to be lower) than the normally set magnetic force (80 mT as an example). This is to reduce the driving torque of the developing roller 106 of the developing device 100, and to reduce the magnetic attractive force by lowering the magnetic force of the layer forming pole N2, thereby reducing the developer G during layer formation (layer regulation). There is also an aim to reduce the load on.

  The developing pole S1 is disposed in the 9 o'clock direction so as to face the outer peripheral surface of the photoreceptor 42 (see FIG. 2). The transport pole N1 is arranged in the 11 o'clock direction, attracts the developer G remaining after the development on the photosensitive member 42 (see FIG. 2), and holds it on the outer peripheral surface of the developing sleeve 106B. The pick-off pole S2 is arranged in the 2 o'clock direction, and the developer G is peeled off from the developing sleeve 106B between the pick-off pole S2 and the pickup pole S3.

  As shown in FIG. 4, the developing sleeve 106B has cap-shaped support members 137A (−Z direction side) and support members 137B (+ Z direction side) that close both ends in the Z direction. . The support members 137A and 137B are formed in an annular shape, and bearings 138A and 138B whose axial direction is the Z direction are fixed inside. The developing sleeve 106B can rotate with respect to the magnet roll 106A by inserting the shaft 106C into the bearings 138A and 138B. Note that minute irregularities are formed on the outer peripheral surface of the developing sleeve 106B, and the developer G can be held on the outer peripheral surface.

  A bearing 142 is fixed to the support wall 103F with the Z direction as an axial direction, and a part of the support member 137B is inserted into the bearing 142. A gear 144 that rotates about the Z direction as an axial direction is attached to the end of the support member 137B in the + Z direction. Accordingly, when the gear 144 rotates, the support members 137A and 137B rotate around the shaft 106C, and the developing sleeve 106B rotates outside the magnet roll 106A.

  On the other hand, in the first stirring chamber 123, a first auger 109 that conveys the developer G while stirring is disposed. The first auger 109 has a rotating shaft 109A arranged along the Z direction, a forward conveying blade 109B as an example of a spiral wing supported on the outer periphery of the rotating shaft 109A, and a reverse conveying blade 109C. doing. The forward conveying blade 109B is provided from the second inlet 133 to the first inlet 132 in order to convey the developer G in the −Z direction.

  The reverse conveying blade 109C is provided in the vicinity of the developer discharge port 134, and conveys the developer G from the first stirring chamber 123 by conveying the developer G in the direction opposite to the conveying direction of the forward conveying blade 109B. 2 It is made to flow into the stirring chamber 124. Further, the rotation shaft 109A is rotatably supported by the front side wall 103G at the −Z direction end portion of the protrusion 126 and the rear side wall 103H at the + Z direction end portion of the container body 103, and the rotation shaft 109A in the + Z direction is supported. A gear 145 is attached to the end.

  As described above, the first auger 109 is disposed opposite to the developing sleeve 106B on the upstream side of the trimmer 108 (see FIG. 3) in the rotation direction of the developing sleeve 106B, and the developing sleeve 106B and the rotation axis direction (Z direction) are aligned. Thus, the forward conveying blade 109B is rotated to convey the developer G in the direction of the rotation axis, and the developer G is supplied to the developing sleeve 106B.

  In the second stirring chamber 124, a second auger 111 that conveys the developer G while stirring is disposed. The second auger 111 has a rotating shaft 111A disposed along the Z direction, a forward conveying blade 111B supported on the outer periphery of the rotating shaft 111A, and a reverse conveying blade 111C. The forward conveying blade 111B is provided from the first inlet 132 to the second inlet 133 in order to convey the developer G in the + Z direction.

  The reverse conveying blade 111C is provided near the second inlet 133, and conveys the developer G from the second stirring chamber 124 by conveying the developer G in a direction opposite to the conveying direction of the forward conveying blade 111B. 1 is allowed to flow into the stirring chamber 123. The rotating shaft 111A is rotatably supported by the front side wall 103G and the rear side wall 103H, and a gear 146 is attached to an end portion in the + Z direction of the rotating shaft 111A.

  The gear 144 of the developing roll 106 is engaged with the gear 145 of the first auger 109 and the intermediate gear 147, and the gear 145 is engaged with the gear 146 of the second auger 111. The gear 144 is arranged so that the rotational force of a motor (not shown) as a drive source is transmitted.

  Here, when the gear 144 is rotated by the motor, the gear 145 is rotated in the + R direction (clockwise direction in FIG. 3) which is the same direction as the gear 144, and the gear 146 is the reverse direction -R direction (counter in FIG. 3). Rotate clockwise. That is, the first auger 109 and the second auger 111 rotate in opposite directions. As the first auger 109 and the second auger 111 rotate, the developer G in the first agitation chamber 123 and the second agitation chamber 124 is conveyed and circulated in opposite directions. At this time, the developer G conveyed by the first auger 109 is supplied to the developing roll 106.

  Subsequently, as shown in FIG. 3, the developer G in the first stirring chamber 123 is conveyed by the rotation of the developing sleeve 106B in the + R direction while being held on the developing sleeve 106B by the pickup pole S3. The developer G held on the developing sleeve 106B enters the space between the outer peripheral surface of the developing sleeve 106B and the tip of the trimmer 108, whereby the layer thickness is regulated, and the photosensitive member 42 (see FIG. 2). Is conveyed to a developing area opposite to.

  The trimmer 108 is a plate-like member whose longitudinal direction is the Z direction. The direction slightly inclined from the Y direction to the X direction is the short direction, and the tip (upper end surface 108A) faces the shaft 106C. Are arranged. That is, the trimmer 108 is disposed below the developing sleeve 106B in the Y direction, is disposed to face the layer forming pole N2 via the developing sleeve 106B, and the thickness of the developer layer on the outer peripheral surface of the developing sleeve 106B is increased. It comes to regulate.

  Next, the blocking block 110 will be described.

  As shown in FIG. 5, a blocking block 110 that blocks the movement of the developer G toward the developing roll 106 is disposed between the developing roll 106 and the first auger 109.

  For example, the blocking block 110 is configured by a block body having a trapezoidal shape in the XY cross section and extending in the same cross-sectional shape in the Z direction. The lower surface is fixed on the flat portion 103B and integrated with the container body 103. Has been. Specifically, the blocking block 110 has a trapezoidal shape surrounded by points F, G, H, and I as viewed in the + Z direction (as viewed in the XY cross section).

  In the trapezoidal FGHI, the line segment FI corresponds to the lower surface of the blocking block 110, and the line segment FG and line segment IH are the left side surface of the blocking block 110 raised in a direction substantially perpendicular to the line segment FI, Corresponds to the right side. The line segment GH corresponds to the upper surface of the blocking block 110. The length of the line segment FG is shorter than the length of the line segment IH, and the line segment GH is inclined obliquely downward from the point H to the point G.

  The left side surface (line segment FG) of the blocking block 110 is disposed adjacent to the right side surface in the X direction of the trimmer 108, but is not fixed to the trimmer 108. Further, the right side surface (line segment IH) of the blocking block 110 is disposed with a gap from the outer peripheral surface of the forward conveying blade 109B of the first auger 109. Further, in the XY plane, the point G is disposed on the lower side by a distance h from the upper end surface 108A of the trimmer 108 in the extending direction of the line segment FG. In the blocking block 110, the line segment FG on the side closer to the trimmer 108 is arranged farther from the developing sleeve 106B than the line segment IH on the side far from the trimmer 108. In the developing device 100, the blocking block 110 and the trimmer 108 serve as an example of a space that opens to the developing sleeve 106B side farther from the developing sleeve 106B than the tip of the trimmer 108 (tip including the point A). A developer circulation chamber 125 is formed. Specifically, the developer circulation chamber 125 is formed by the upper surface of the blocking block 110 and the right side surface of the trimmer 108, and is further surrounded by the outer peripheral surface of the developing sleeve 106B.

  On the other hand, when the developing device 100 is viewed in the Z direction, the center of the tip of the trimmer 108 that faces the developing sleeve 106B (the point that bisects the upper end surface 108A) is the point A, and the tip of the layer forming pole N2 on the developing sleeve 106B side. The center of the part is point B, and the center of the rotation axis of the first auger 109 is point C. Note that the position of the point A is not limited to the center of the tip, and may be set at another position on the upper end surface 108A.

  Of the tangent lines drawn from the point A to the outer periphery of the rotation trajectory of the forward conveying blade 109B, the tangent line closer to the trimmer 108 is L1 (hereinafter referred to as a virtual plane L1), and the outer peripheral surface (forward order) Of the tangent lines drawn on the outer periphery of the rotation trajectory of the conveying blade 109B, the tangent line closer to the trimmer 108 is L2 (hereinafter referred to as virtual plane L2), and the line segment connecting point A and point C is L3 (hereinafter referred to as virtual plane). L3). A contact point between the virtual plane L1 and the forward conveyance blade 109B is a point D, and a contact point between the virtual plane L2 and the forward conveyance blade 109B is a point E.

  Here, the blocking block 110 is disposed in the housing 102 across the virtual planes L1, L2, and L3.

(Comparative example)
Next, a first comparative example in which the blocking block 110 is not provided will be described.

  As shown in FIG. 6A, when the first auger 109 transports the developer G, when the first auger 109 rotates in the + R direction, the developer G is forced from the rotating spiral forward transport blade 109B. Receive F1. That is, the forward conveyance blade 109B gives the developer G a force that moves in the −Z direction, which is the axial direction, and also a force F1 that moves in the radial direction away from the circumferential direction and the rotation shaft 109A.

  Therefore, as shown in FIG. 6B, circumferential and radial forces F1 act on the developer G between the developing sleeve 106B and the first auger 109. That is, the developer G between the developing sleeve 106B and the first auger 109 is applied not only with the magnetic force of the magnet roll 106A (see FIG. 3) but also with a force F1 in the direction from the forward conveying blade 109B toward the developing sleeve 106B. In some cases, the force is held on the outer peripheral surface of the developing sleeve 106B. For this reason, the portion receiving the force F1 from the forward conveying blade 109B retains a large amount of the developer G, or the density of the developer G is partially increased. There may be a case where the amount of the agent G held is uneven.

  As shown in FIG. 8A, when the first auger 109 rotates and transports the developer G, the amount of the developer G decreases in the downstream portion in the transport direction with respect to the forward transport blade 109B. The amount of developer G tends to increase in a portion upstream of the conveying blade 109B. For this reason, the amount of the developer G increases or decreases for each pitch of the forward conveying blade 109B (the distance W1 shown in the drawing), and the surface of the developer G is wavy uneven in the Z direction along the axial direction of the first auger 109. It may become.

  In this case, the amount of the developer G held on the outer peripheral surface of the developing sleeve 106B (see FIG. 5) easily varies depending on the position of the first auger 109 in the axial direction, and the developer G held on the developing sleeve 106B is different. The amount is increased or decreased in the axial direction to cause unevenness (a portion where the amount of developer G on the downstream side in the transport direction in the first auger 109 is small is conspicuous).

  For this reason, as shown in FIG. 8C, on the developing sleeve 106B in the developing device 200 of the first comparative example, a periodic oblique pattern corresponding to the forward conveying blade 109B (see FIG. 8A). (A site where the amount of developer is large is G1, and a site where the amount of developer is small is G2). Since the developing device 200 of the first comparative example is the same as the developing device 100 except for the blocking block 110, the illustration of other parts is omitted.

  As described above, in the first comparative example, when the latent image on the photosensitive member 42 (see FIG. 2) is developed in a state where the periodically slanting pattern is formed on the developing sleeve 106B, the developed image and There are cases where periodic oblique shading, so-called auger marks, also occur in the image on the recording paper P. In particular, when a halftone image that is a low-density image is printed, this auger mark is likely to be prominent.

(Function)
Next, the operation of the first embodiment will be described.

  As shown in FIG. 4, in each developing device 100, the first auger 109 and the second auger 111 rotate, so that the developer G stored in the container main body 103 (housing 102) is conveyed while being stirred. The developer G conveyed to the first stirring chamber 123 is supplied to the developing sleeve 106B and held on the outer peripheral surface of the developing sleeve 106B. The thickness of the developer G on the outer peripheral surface of the developing sleeve 106B is regulated by a trimmer 108 (see FIG. 3).

  Here, as shown in FIG. 7, in the developing device 100, a blocking block 110 is disposed between the developing sleeve 106 </ b> B and the first auger 109. For this reason, even if the developer G conveyed by the first auger 109 is pushed in the radial direction from the forward conveying blade 109B (force F1 in FIG. 6) and moves toward the developing sleeve 106B, it moves by the blocking block 110. Will be shut off. That is, the force acting on the developer G in the direction from the first auger 109 toward the developing sleeve 106B is hindered by the blocking block 110, so that the developer G near the developing sleeve 106B is transferred from the first auger 109 to the developing sleeve. It becomes difficult to receive the force toward 106B directly.

  Specifically, since the blocking block 110 intersects the virtual plane L1, when the first auger 109 rotates in the + R direction, the developer G is tangentially applied from the forward conveying blade 109B passing through the point D by the tangential force F2. In response to the movement toward the trimmer 108 side, the movement is blocked by the blocking block 110.

  Further, since the blocking block 110 intersects the virtual plane L2, when the first auger 109 rotates in the + R direction, the developer G receives a tangential force F3 from the forward conveying blade 109B passing through the point E. Further, even if the magnetic force (attracting force) of the pickup pole S3 is received to move toward the developing sleeve 106B, the movement is blocked by the blocking block 110.

  As described above, in the developing device 100, it is difficult to be affected by the fluctuation of the developer G by the first auger 109, and the developer G is easily held on the developing sleeve 106B only by the magnetic force of the magnet roll 106A. Further, the force from the first auger 109 is applied to suppress a large amount of the developer G from being held on the developing sleeve 106B, and the density of the developer G is suppressed from being partially increased. Thereby, in the developing device 100, as shown in FIG. 8B, unevenness of the developer layer on the developing sleeve 106B caused by the rotation of the first auger 109 (see FIG. 7) is suppressed. Further, since unevenness of the developer layer in the axial direction on the developing sleeve 106B is suppressed, in the image forming apparatus 10 shown in FIG. 1, a developer image (toner image) in the width direction intersecting the conveyance direction of the recording paper P is used. ) Is suppressed.

  As shown in FIG. 7, in the developing device 100, since the blocking block 110 intersects the virtual plane L3, the developer G in the vicinity of the developing sleeve 106B has a force from the forward conveying blade 109B below the virtual plane L3. Although it is difficult to receive, the force F4 from the forward conveying blade 109B on the upper side of the virtual plane L3 is received. On the other hand, since the direction of the force F4 is not the direction toward the developing sleeve 106B and the trimmer 108, unevenness of the developer layer on the developing sleeve 106B is suppressed. Since the virtual plane L3 is set through the center of the rotation shaft 109A of the first auger 109, it is possible to suppress unnecessarily blocking the region that does not affect the developer G toward the developing sleeve 106B.

  Further, in the developing device 100, the trimmer 108 is disposed below the developing sleeve 106B, and the developer G is stored in the housing 102 up to a height not less than the upper end portion 110A of the blocking block 110. (For example, the developing device 100 is provided with a toner replenishment sensor (not shown) to manage the amount of developer G stored). For this reason, even when the developer G in the housing 102 is consumed, the developer G exists at a height higher than the upper end portion 110 </ b> A of the blocking block 110. As a result, a decrease in the supply amount of the developer G around the pickup electrode S3 is suppressed.

  Further, in the developing device 100, since the blocking block 110 is integrated with the housing 102, the blocking block 110 is more rigid than a configuration in which the blocking block 110 is not fixed to the housing 102. Further, since the rigidity of the blocking block 110 is increased, when the blocking block 110 and the trimmer 108 are brought into contact with each other, the distortion of the trimmer 108 is suppressed, and the change in the distance between the outer peripheral surface of the developing roll 106 and the tip of the trimmer 108 is changed. Is suppressed.

  Here, a second comparative example in which the developer circulation chamber 125 is not formed will be described.

  As shown in FIG. 9B, in the developing device 210 of the second comparative example, a blocking block 212 is provided instead of the blocking block 110. The developing device 210 of the second comparative example is the same as the developing device 100 except for the configuration other than the blocking block 212. Therefore, the illustration of other parts is omitted, or the same part as the developing apparatus 100 is developed. The same reference numerals as those of the apparatus 100 are given.

  The blocking block 212 of the second comparative example has a shape in which a rectangular parallelepiped is viewed in the longitudinal direction and one upper end corner portion is cut obliquely, and the cut portion is an inclined surface 212A. The inclined surface 212A is a surface extending obliquely upward toward one end of the upper end surface 108A of the trimmer 108. That is, the blocking block 212 is disposed closer to the developing sleeve 106B on the side closer to the trimmer 108 than on the side farther from the trimmer 108. Note that the space on the inclined surface 212A of the second comparative example does not have an opening, and therefore differs from the developer circulation chamber 125 (see FIG. 9) of the present embodiment.

  In the developing device 210 of the second comparative example, as shown on the left side of FIG. 9B, the fluidity of the developer G existing between the inclined surface 212A of the blocking block 212 and the developing sleeve 106B during initial use. Therefore, the amount of the developer G that flows toward the layer restricting portion between the upper end surface 108A of the trimmer 108 and the developing sleeve 106B increases. For this reason, the pressure which acts on a layer control part increases, and the quantity of the developer G on the developing sleeve 106B after passing a layer control part increases.

  However, in the developing device 210 of the second comparative example, as shown on the right side of FIG. 9B, the inclined surface 212A of the blocking block 212 and the developing sleeve are used, for example, after thousands of sheets are developed (timed). A part of the developer G accumulated between 106B stays without flowing and forms a non-moving region A2. For this reason, the developer G flowing toward the layer restricting portion between the upper end surface 108A of the trimmer 108 and the developing sleeve 106B becomes a flow in only one direction, and the pressure acting on the layer restricting portion is reduced. Then, the interval between the spikes of the magnetic carrier CA (see FIG. 3) on the developing sleeve 106B increases, the density of the developer G per unit area decreases, and the amount of the developer G on the developing sleeve 106B decreases.

  On the other hand, as shown on the left side of FIG. 9A, the developing device 100 of the present embodiment is a developer G that exists between the inclined surface 110B of the blocking block 110 and the developing sleeve 106B during initial use. The developer G ′, which is a part, moves along the side surface 108B of the trimmer 108 in the developer circulation chamber 125 and is refluxed. Thereby, the fluidity of the developer G is increased, and the amount of the developer G flowing toward the layer regulating portion between the upper end surface 108A of the trimmer 108 and the developing sleeve 106B increases. For this reason, the pressure which acts on a layer control part increases, and the quantity of the developer G on the developing sleeve 106B after passing a layer control part increases.

  Further, as shown in the right side of FIG. 9A, the developing device 100 is provided with a developer circulation chamber 125. For example, even when the developing device 100 is used after being developed (thousands), The amount of the developer G staying in the developer circulation chamber 125 is small. For this reason, the non-moving area A1 is smaller than the non-moving area A2 of the second comparative example (see FIG. 9B), and the fluidity of the developer G is good. As a result, the developer G flowing toward the layer restricting portion between the upper end surface 108A of the trimmer 108 and the developing sleeve 106B becomes a flow in a plurality of directions, and is maintained in a state where the pressure acting on the layer restricting portion is high. Further, the interval between the spikes of the magnetic carrier CA (see FIG. 3) on the developing sleeve 106B is maintained, and the density of the developer G per unit area is maintained, so that the developing sleeve 106B after passing through the layer regulating portion is maintained. The amount of the developer G is maintained in a large state. Further, in the developing device 100, since the flowability of the developer G in the developer circulation chamber 125 is good over time, the frequency of maintenance is less than that of the second comparative example.

  Here, FIG. 10 shows the trimmer 108 when the distance h from the tip of the trimmer 108 in FIG. 5 to the point G of the blocking block 110 is changed to h1, h2, h3 (h1 <h2 <h3). Developer change amount per unit area on the developing sleeve 106B after passing (change amount over time with respect to the initial time (for example, after image formation for several thousand sheets)) Δm1, Δm2, Δm3 (absolute values | Δm1 |> | The change of Δm2 |> | Δm3 |) is shown by a graph GA. As shown in FIG. 10, as the distance h becomes longer and the developer circulation chamber 125 (see FIG. 5) becomes larger, the developer change amount per unit area on the developing sleeve 106B after passing through the trimmer 108 decreases. I know. In FIG. 10, in the second comparative example (see FIG. 9B), the developer change amount Δm0 (absolute value | Δm0 |> | Δm1 |) is obtained when h = 0. It can be seen that the amount of developer change per unit area is larger than that.

(Second Embodiment)
Next, an example of a developing device and an image forming apparatus according to the second embodiment of the present invention will be described. Note that the same reference numerals as those in the first embodiment are given to the same members and parts as those in the first embodiment described above, and the description thereof is omitted.

  FIG. 11 shows an image forming apparatus 150 and a developing apparatus 160 as an example of the second embodiment. The image forming apparatus 150 is the same as the image forming apparatus 10 according to the first embodiment shown in FIGS. 1 and 2 except that the left and right sides are reversed except for the document reading unit 18, and the photosensitive member 42 and the charging roll above the intermediate transfer belt 48. 46, the exposure device 60, the developing device 160, and the cleaning roll 54 are arranged. The units constituting the image forming apparatus 150 are substantially the same as the image forming apparatus 10 except for the developing device 160, and thus illustration and description thereof are omitted.

  As shown in FIG. 11, the developing device 160 includes a housing 162 as an example of a housing in which the developer G is accommodated, a developing roll 166, and a developer G layer held on the outer peripheral surface of the developing roll 166. It has a trimmer 108 that regulates the thickness, a first auger 109 that supplies developer G to the developing roll 166, a second auger 111, and a blocking block 170 as an example of a blocking member.

  The housing 162 includes a container main body 163 and a cover member 164 that closes the upper portion of the container main body 163. Further, the housing 162 is arranged on the left side when viewed in the + Z direction, and a developing roll chamber 172 in which the developing roll 166 is accommodated, and a first stirring chamber that is provided on the right side of the developing roll chamber 172 and in which the first auger 109 is accommodated. 173 and a second stirring chamber 174 provided below the first stirring chamber 173 and on the lower right side of the developing roll chamber 172 and in which the second auger 111 is accommodated. The first stirring chamber 173 and the second stirring chamber 174 are partitioned by a partition wall 163A. In addition, although the container main body 163 is provided with the side wall in the edge part of + Z direction and -Z direction, illustration is abbreviate | omitted. In addition, an inlet (not shown) that connects the first stirring chamber 173 and the second stirring chamber 174 up and down is formed at the + Z direction end and the −Z direction end of the partition wall 163A.

  The cover member 164 includes a right side wall 164A that is fixed to the container body 163, an inclined wall 164B that extends diagonally upward to the left from the upper end of the right side wall 164A, and an upper wall that extends so as to approach the horizontal continuously from the upper end of the inclined wall 164B. 164C. The upper surface of the blocking block 170 is fixed to and integrated with the lower surface of the upper wall 164C. The upper end of the trimmer 108 is attached to the left end of the cover member 164 with a screw 128.

  The developing roll 166 is formed in a columnar shape and is fixedly supported on the container body 163 via a shaft 166C. The developing roll 166 is a cylindrically formed magnet roll 166A, and is formed in a cylindrical shape and is rotatably supported outside the magnet roll 166A. And a developing sleeve 166B as an example of the developer holding member. That is, the magnet roll 166A is disposed inside the developing sleeve 166B.

  The magnet roll 166A is provided with a plurality of magnetic poles along the outer peripheral surface (circumferential direction). Specifically, the magnet roll 166A is counterclockwise from the right side close to the first auger 109 when viewed in the axial direction (Z direction) of the shaft 166C. A pickup pole NB, a layer forming pole SB, a transport pole NC, a developing pole SA, and a pickoff pole NA are provided in the rotation direction as examples of the attracting pole. Magnetic field lines are generated from the pick-off pole NA toward the development pole SA, from the transport pole NC toward the development pole SA and the layer formation pole SB, and from the pickup pole NB toward the layer formation pole SB. Omitted.

  Here, in the following description, when the magnet roll 166A is viewed in the axial direction, the position of each magnetic pole will be described assuming that the upper position is 12:00 and the lower position is 6 o'clock. As an example, the pickup pole NB is arranged in the direction of about 3 o'clock, and attracts the developer G and holds it on the outer peripheral surface of the developing sleeve 166B. The layer forming pole SB is arranged in the direction of approximately 12:00 facing the lower end surface 108C of the trimmer 108, and on the outer peripheral surface of the developing sleeve 166B in a state where a plurality of magnetic carriers CA (see FIG. 3) are raised. Hold. Note that the magnetic force of the layer forming pole SB in the present embodiment is lower (set to be lower) than the normally set magnetic force (80 mT as an example). This is to reduce the driving torque of the developing roller 166 of the developing device 160, and to reduce the magnetic attractive force by reducing the magnetic force of the layer forming pole SB to reduce the magnetic attractive force, thereby developing G during layer formation (layer regulation). There is also an aim to reduce the load on.

  The transport pole NC is disposed in the 10 o'clock direction, and attracts the developer G after passing through the trimmer 108 and holds it on the outer peripheral surface of the developing sleeve 166B. The development pole SA is disposed in the 8 o'clock direction so as to face the outer peripheral surface of the photoreceptor 42. The pick-off pole NA is disposed in the 5 o'clock direction, and the developer G is peeled from the developing sleeve 166B between the pick-off pole NA and the pickup pole NB.

  The first auger 109 rotates in the −R direction, and the second auger 111 rotates in the + R direction. Then, the developer G is stirred and conveyed through an inlet (not shown) of the partition wall 163A.

  Here, the developer G in the first stirring chamber 173 is conveyed by the rotation of the developing sleeve 166B in the −R direction while being held on the developing sleeve 166B by the pickup pole NB. The developer G held on the developing sleeve 166B enters between the outer peripheral surface of the developing sleeve 166B and the lower end surface 108C of the trimmer 108, whereby the thickness of the layer is regulated, and the developing facing the photoreceptor 42 is performed. Conveyed to the area.

  Next, the blocking block 170 will be described.

  As shown in FIG. 11, a blocking block 170 that blocks the movement of the developer G moving toward the developing roll 166 is disposed between the developing roll 166 and the first auger 109.

  For example, the blocking block 170 is configured by a block body having a trapezoidal shape in the XY cross section and extending in the same cross-sectional shape in the Z direction, and the upper surface is fixed to the lower surface of the upper wall 164C so as to be integrated with the housing 162. Has been.

  As shown in FIG. 12, the blocking block 170 has a trapezoidal shape surrounded by points F, G, H, and I as viewed in the + Z direction (as viewed in the XY cross section). In the trapezoidal FGHI, the line segment FI corresponds to the upper surface of the blocking block 170, and the line segment FG and the line segment IH are on the left side surface and the right side surface of the blocking block 170 extending in a direction substantially perpendicular to the line segment FI. Equivalent to. The line segment GH corresponds to the lower surface of the blocking block 170. The length of the line segment FG is shorter than the length of the line segment IH, and the line segment GH is inclined obliquely upward from the point H to the point G.

  The left side surface (line segment FG) of the blocking block 170 is disposed adjacent to the right side surface in the X direction of the trimmer 108, but is not fixed to the trimmer 108. Further, the right side surface (line segment IH) of the blocking block 170 is disposed with a space from the outer peripheral surface of the forward conveying blade 109B of the first auger 109. Further, in the XY plane, the point G is disposed on the upper side by a distance h from the lower end surface 108C of the trimmer 108 in the extending direction of the line segment FG, that is, the blocking block 170 is closer to the trimmer 108. The line segment FG is arranged farther from the developing sleeve 166B than the line segment IH on the side far from the trimmer 108. In the developing device 160, the blocking block 170 and the trimmer 108 serve as an example of a space that opens away from the developing sleeve 166B from the tip of the trimmer 108 (tip including the point A) to the developing sleeve 166B. A developer circulation chamber 175 is formed. Specifically, the developer circulation chamber 175 is formed by the lower surface of the blocking block 170 and the right side surface of the trimmer 108, and is further surrounded by the outer peripheral surface of the developing sleeve 166B.

  On the other hand, when the developing device 160 is viewed in the + Z direction, the center of the tip of the trimmer 108 facing the developing sleeve 166B (the point where the lower end surface 108C is divided into two equal parts) is the point A, and the tip of the layer forming pole SB on the developing sleeve 166B side. The center of the part is point B, and the center of the rotation axis of the first auger 109 is point C.

  Of the tangent lines drawn from the point A to the outer periphery of the rotation trajectory of the forward conveying blade 109B, the upper tangent line is L4 (hereinafter referred to as the virtual plane L4), and from the point B the outer peripheral surface of the first auger 109 (the forward conveying blade 109B Of the tangent lines drawn on the outer periphery of the rotation locus, the upper tangent line is L5 (hereinafter referred to as virtual plane L5), and the line segment connecting point A and point C is L6 (hereinafter referred to as virtual plane L6). A contact point between the virtual plane L4 and the forward conveyance blade 109B is a point D, and a contact point between the virtual plane L5 and the forward conveyance blade 109B is a point E. Here, the blocking block 170 is disposed across the virtual planes L4, L5, and L6 in the housing 162 (see FIG. 11).

(Function)
Next, the operation of the second embodiment will be described.

  As shown in FIG. 11, in the developing device 160, the developer G accommodated in the housing 162 is conveyed while being agitated by the rotation of the first auger 109 and the second auger 111. The developer G conveyed to the first stirring chamber 173 is supplied to the developing sleeve 166B and held on the outer peripheral surface of the developing sleeve 166B. The layer thickness of the developer G on the outer peripheral surface of the developing sleeve 166B is regulated by the trimmer 108.

  Here, as shown in FIG. 12, in the developing device 160, a blocking block 170 is disposed between the developing sleeve 166 </ b> B and the first auger 109. For this reason, even if the developer G transported by the first auger 109 is pushed in the radial direction from the forward transport blade 109B and moves in the direction of the developing sleeve 166B, the movement is blocked by the blocking block 170. That is, the force acting on the developer G in the direction from the first auger 109 toward the developing sleeve 166B is hindered by the blocking block 170, so that the developer G near the developing sleeve 166B is transferred from the first auger 109 to the developing sleeve. It becomes difficult to receive the force toward 166B directly.

  More specifically, since the blocking block 170 intersects the virtual plane L4, when the first auger 109 rotates in the −R direction, the developer G receives a tangential force from the forward conveying blade 109B that passes through the point D. Even if F5 is received and moved toward the trimmer 108 side, the movement is blocked by the blocking block 170.

  Further, since the blocking block 170 intersects the virtual plane L5, when the first auger 109 rotates in the -R direction, the developer G applies a tangential force F6 from the forward conveying blade 109B passing through the point E. Further, even if the magnetic force (attracting force) of the pickup pole NB is received and an attempt is made to move toward the developing sleeve 166B, the movement is blocked by the blocking block 170.

  Thus, in the developing device 160, the developer G is easily held on the developing sleeve 166B only by the magnetic force of the magnet roll 166A. Then, the force from the first auger 109 is applied to prevent the developer G from being held on the developing sleeve 166B in a large amount, and the density of the developer G is suppressed from being partially increased. Thereby, in the developing device 160, unevenness of the developer layer on the developing sleeve 166B caused by the rotation of the first auger 109 is suppressed. Since unevenness of the developer layer in the axial direction on the developing sleeve 166B is suppressed, in the image forming apparatus 150, unevenness of the developer image (toner image) in the width direction intersecting the conveyance direction of the recording paper P is suppressed. It is suppressed.

  Further, in the developing device 160, since the blocking block 170 intersects the virtual plane L6, the developer G in the vicinity of the developing sleeve 166B is less likely to receive a force from the forward conveying blade 109B above the virtual plane L6. However, the force F7 from the forward conveying blade 109B below the virtual plane L6 is received. However, since the direction of the force F7 is not the direction toward the developing sleeve 166B and the trimmer 108, unevenness of the developer layer on the developing sleeve 166B is suppressed. Since the imaginary plane L6 is set through the center of the rotation shaft 109A of the first auger 109, the blocking block 170 is prevented from blocking more than necessary to an area that does not affect the developer G toward the developing sleeve 166B. Is done.

  In addition, as illustrated in FIG. 11, in the developing device 160, since the blocking block 170 is integrated with the housing 162, the rigidity of the blocking block 170 is increased as compared with a configuration in which the blocking block 170 is not fixed to the housing 162. . Further, since the rigidity of the blocking block 170 is increased, when the blocking block 170 and the trimmer 108 are brought into contact with each other, the distortion of the trimmer 108 is suppressed, and the change in the distance between the outer peripheral surface of the developing roll 166 and the lower end of the trimmer 108 is changed. Is suppressed.

  Further, since the developer circulating chamber 175 is formed in the developing device 160, the developer G is refluxed in the developer circulating chamber 175. As a result, the fluidity of the developer G is improved, so that the amount of the developer G staying in the developer circulation chamber 125 is small even when used (elapsed time) after development for several thousand sheets, for example. Become. For this reason, the pressure acting on the layer restricting portion between the lower end surface 108C of the trimmer 108 and the developing sleeve 166B is maintained in a high state. Then, the interval between the spikes of the magnetic carrier CA (see FIG. 3) on the developing sleeve 166B is maintained, and the density of the developer G per unit area is maintained, so that the developing sleeve 166B after passing through the layer regulating portion is maintained. The amount of the developer G is maintained in a large state.

  In addition, this invention is not limited to said embodiment.

  The inclined surfaces of the blocking blocks 110 and 170 are not limited to flat surfaces, and may be curved surfaces that are curved along the direction in which the developer G is recirculated. Further, the side surfaces of the blocking blocks 110 and 170 may also be configured as curved surfaces. Furthermore, the front-end | tip part of the interruption | blocking blocks 110 and 170 is not restricted to an acute angle thing, You may be comprised by the curved surface. In addition, the blocking blocks 110 and 170 are not necessarily manufactured separately and fixed to the housings 102 and 162, but the blocking blocks 110 and 170 may be formed (molded) integrally with the housings 102 and 162 from the beginning. .

  Further, the developer circulation chamber may be formed by forming a facing portion (facing surface) facing the developing sleeve 106B of the blocking blocks 110 and 170 as a recess opening toward the developing sleeve 106B. That is, the developer circulation chamber may be formed by the blocking blocks 110 and 170 alone.

10 Image Forming Apparatus 42 Photoconductor (Example of Image Holding Member)
48 Intermediate transfer belt (an example of transfer means)
52 Primary transfer roll (an example of transfer means)
79 Secondary transfer roll (an example of transfer means)
100 Developing Device 102 Housing (Example of Housing)
106A Magnet roll (an example of a magnetic force generator)
106B Development sleeve (an example of a developer holder)
108 Trimmer (an example of a developer regulating member)
109 First auger (an example of a supply member)
109B Forward conveying blade (example of wing)
110 Blocking block (an example of a blocking member)
125 Developer circulation chamber (example of open space)
150 Image Forming Device 160 Developing Device 162 Housing (Example of Housing)
166A Magnet roll (an example of a magnetic force generator)
166B Development sleeve (an example of a developer holder)
170 Blocking block (an example of a blocking member)
175 Developer circulation chamber (example of open space)
CA magnetic carrier (an example of magnetic particles)
G Developer L1 Tangent L2 Tangent L3 Segment L4 Tangent L5 Tangent L6 Segment N1 Conveying pole (an example of a magnetic pole)
N2 layer forming pole NA Pickoff pole (example of magnetic pole)
NB Pickup pole (an example of an attracting pole)
NC carrier pole (an example of magnetic pole)
S1 Development pole (example of magnetic pole)
S2 Pickoff pole (example of magnetic pole)
S3 Pickup pole (an example of an attracting pole)
SA Development pole (example of magnetic pole)
SB layer forming electrode TA toner image (example of developer image)

Claims (4)

A developer holding body formed in a cylindrical shape, holding a developer containing magnetic particles on the outer peripheral surface, and rotating in the circumferential direction;
A plurality of magnetic poles arranged inside the developer holding body and including an attracting pole for attracting the developer and a layer forming pole for forming a layer of the developer along the circumferential direction of the developer holding body. A magnetic force generator arranged
A developer regulating member that is disposed opposite to the layer forming electrode via the developer holder and regulates the thickness of the developer layer on the outer peripheral surface of the developer holder;
The developer holding member is disposed on the upstream side of the developer regulating member in the rotation direction of the developer holding member so as to face the developer holding member, the rotation axis direction of the developer holding member is aligned, and the helical wing is rotated. A supply member for conveying the developer in the direction of the rotation axis and supplying the developer to the developer holding body;
The tip of the developer regulating member, which is integrated with a housing for accommodating the developer supplied by the supply member and faces the developer holding member when viewed in the direction of the rotation axis, is indicated by the point A. Of the tangent lines drawn from the point A to the outer periphery of the rotation locus of the blade, the developer regulation is defined as a point B at the center of the leading end on the developer holding body side of the pole and a point C as the rotation axis center of the supply member. The point A and the point C are connected to the tangent line L1 closer to the member, the tangent line L2 closer to the developer regulating member among the tangent lines drawn from the point B to the outer periphery of the rotation locus of the wing portion, and the point A. A blocking member disposed across the line segment L3;
A developing device.   The said interruption | blocking member is independent or with the said developer control member, and forms the space which leaves | separates from the said developer holding body rather than the front-end | tip part of the said developer control member, and opens to the said developer holding body side. Development device. The developer regulating member is disposed below the developer holding body,
The developing device according to claim 1, wherein the developer is stored in the casing up to a height equal to or higher than an upper end portion of the blocking member. An image holding member for holding the latent image on the outer peripheral surface;
The developing device according to any one of claims 1 to 3, wherein the latent image is developed with a developer to form a developer image.
Transfer means for transferring the developer image developed by the developing device to a recording medium;
An image forming apparatus.

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