JP2019109341A - Developing device and image forming apparatus - Google Patents

Abstract

To provide a developing device that can improve fluidity of developer.SOLUTION: A developing device comprises: a developer container 114n that stores a developer; a developing sleeve 114a that carries the developer; a stirring member 114g that is provided rotatably along the axial direction of the developing sleeve 114a, and stirs the developer inside the developer container 114n; and magnets 114h that are provided on an outer face 114n1 of the developer container 114n along the rotation loci 1 of tips 114g5 of stirring blades 114g4 of the stirring member 114g.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a developing device provided in an image forming apparatus such as a copying machine or a printer.

  In an electrophotographic image forming apparatus such as a copying machine and a printer, an electrostatic latent image is formed on the surface of a photosensitive member, and a developing agent supplies a developer to the photosensitive member to develop the electrostatic latent image. Thereafter, the toner image formed on the photosensitive member is transferred to a recording material such as paper, and fixed by a fixing device.

  The developing device of the comparative example will be described using FIGS. 3 (c), 4 (b) and 5. In the electrophotographic image forming apparatus 6 shown in FIG. 1, a developer (toner) is used. In the image forming apparatus 6, the developer in the developing device 114 is consumed along with the image formation. The developer is supplied from the toner bottle 50 to the hopper 41 in order to supply the consumed developer. Further, the conveyance path 114c is provided on the upstream side of the conveyance direction of the developer in the conveyance path 114c provided in the developing device 114 shown in FIGS. 3C and 4B from the hopper 41. The developer is supplied in 114c.

  The developer replenished in the conveyance path 114c is conveyed in the longitudinal direction of the conveyance path 114c by the conveyance screw 114d rotatably provided in the conveyance path 114c. The conveying screw 114d is controlled so as to supply the developer supplied into the conveying path 114c from the hopper 41 via the supply port 114b connected by the main body toner conveying path 60 substantially uniformly in the longitudinal direction of the conveying path 114c. ing. A restriction wall 114 e is provided between the conveyance path 114 c and the stirring chamber 20 along the longitudinal direction of the conveyance path 114 c. The regulating wall 114e is provided with an upper edge portion 114f that regulates the amount of developer falling from the transport path 114c into the stirring chamber 20 along the developer transport direction of the transport path 114c.

  As shown in FIG. 5, the upper edge portion 114f is inclined such that the height thereof gradually decreases from the upstream side to the downstream side of the developer transport direction of the transport path 114c. From the upstream side, the developer successively climbs over the upper edge portion 114f of the regulating wall 114e provided along the transport path 114c and drops into the stirring chamber 20 little by little. The developer remaining without dropping is further transported downstream in the transport path 114c by the transport screw 114d, and drops into the stirring chamber 20 beyond the upper edge portion 114f of the regulating wall 114e at the transport destination. By repeating this, the developer replenished from the hopper 41 into the conveyance path 114c is supplied with a predetermined distribution in the longitudinal direction of the conveyance path 114c. This distribution is called "fall amount distribution".

  The developer dropped into the agitating chamber 20 is agitated by the agitating member 114g rotatably provided in the agitating chamber 20 and the new and old developers are agitated and conveyed toward the developing sleeve 114a serving as a developer carrier. The developer carried on the surface of the developing sleeve 114a is regulated in layer thickness by the developer layer regulating member 114k, supplied to the electrostatic latent image formed on the surface of the photosensitive drum 112, and developed as a toner image .

  The developer that has dropped into the stirring chamber 20 beyond the upper edge portion 114f of the restriction wall 114e of the conveyance path 114c is stirred by the stirring member 114g while the new and old developers are stirred while being conveyed in a predetermined direction. The developer falling into the stirring chamber 20 beyond the upper edge portion 114f of the regulation wall 114e of the conveyance path 114c falls into the stirring chamber 20 with a predetermined distribution in the longitudinal direction of the conveyance path 114c.

  For this reason, if the developer is not conveyed while being conveyed in the direction of the rotary shaft 114g1 of the agitating member 114g and the developer is not stirred, nonuniformity of the developer also occurs in the direction of the rotary shaft 114g1 of the agitating member 114g. Unevenness occurs in various physical properties. For example, when the developer is positively dropped into the stirring chamber 20 on the upstream side of the transport direction of the developer in the transport path 114c, the old development is generated in the stirring chamber 20 on the downstream side of the transport direction of the developer on the transport path 114c. Many agents will be deposited.

  As a result, the old developer deposited in the agitating chamber 20 on the downstream side of the developer transport direction of the transport path 114c degrades in durability, a desired charge amount can not be obtained, and development defects such as low toner concentration occur. In addition, the new developer positively replenished in the stirring chamber 20 on the upstream side of the transport direction of the developer in the transport path 114c is an external additive that promotes frictional charging on the surface and an external additive that improves fluidity. Many are added.

  Those external additives are liberated along with the supply of the developer, and the amount of the liberated external additive tends to increase in the stirring chamber 20 on the upstream side of the developer transport direction of the transport path 114c. The free external additive is conveyed from the stirring chamber 20 into the developing chamber 114i by the rotation of the stirring member 114g, strongly adheres on the surface of the developing sleeve 114a provided in the developing chamber 114i, and on the surface of the developing sleeve 114a. There has been a problem that the desired developer can not be carried.

  In Patent Document 1, as shown in FIG. 5, the height of the upper edge portion 114f of the regulating wall 114e is inclined so as to decrease from the upstream side to the downstream side of the transport direction of the developer on the transport path 114c. Furthermore, the surface width W of the upper edge portion 114 f is formed to be wider as the height of the upper edge portion 114 f of the restriction wall 114 e becomes lower. Therefore, the height of the developer stacked on the surface width W of the upper edge portion 114f of the restriction wall 114e increases as the height of the upper edge portion 114f of the restriction wall 114e decreases. .

  Thus, the developer conveyed in the conveyance path 114c is stacked on the surface width W of the upper edge portion 114f of the regulation wall 114e, and the developer is regulated by the developer itself stacked on the surface width W of the upper edge portion 114f. A wall is formed. As a result, the developer conveyed in the conveyance path 114c falls into the agitating chamber 20 so that the developer overlies the developer regulation wall formed by being laminated on the surface width W of the upper edge portion 114f by the developer itself. While being transported in the transport path 114c in the longitudinal direction.

  As a result, when the cohesion degree of the developer changes according to the use environment, the height of the developer regulating wall by the developer itself which is formed by being laminated on the surface width W of the upper edge portion 114f changes. Then, it becomes possible to control uniformly the amount of drop of the developer falling from the conveyance path 114c into the stirring chamber 20 in the longitudinal direction of the conveyance path 114c.

JP, 2011-150318, A

  In Patent Document 1, the developer control wall is formed of the developer itself on the surface width W of the upper edge portion 114f of the control wall 114e. Therefore, the developer regulation wall formed by the developer itself may be broken on the surface width W of the upper edge portion 114f of the regulation wall 114e due to the variation of the cohesion degree of the developer and the vibration at the time of operation. In addition, when the developer forming the developer regulating wall is replaced, the height of the developer regulating wall formed by the developer itself changes.

  As a result, the distribution of the falling amount of developer in the longitudinal direction of the transport path 114c is biased. As described above, when the distribution of the amount of falling developer can not be made uniform, even if the developer dropped into the stirring chamber 20 is stirred by the stirring member 114g, the amount of developer is made uniform in the direction of the rotating shaft 114g1 of the stirring member 114g. I can not do it. For this reason, agitation of the developer in one direction of the rotary shaft 114g of the agitating member 114g in the agitating chamber 20 becomes uneven.

  If the developer is not uniformly stirred in the direction of the rotary shaft 114g of the stirring member 114g in the stirring chamber 20, the uniformity of the image density at the time of image formation is affected. As shown in FIG. 6, it is also conceivable to provide slits 114g2, 114g3 and openings in the agitating blade 114g4 to promote the movement of the agitating member 114g in the direction of the rotation shaft 114g1 of the developer. However, this alone may not be sufficient to agitate the developer in the agitating chamber 20, causing problems such as uneven density in the output image and image defects such as reduced density.

  The present invention solves the above-mentioned problems, and an object of the present invention is to provide a developing device capable of improving the flowability of a developer.

  A representative configuration of a developing device according to the present invention for achieving the above object is a developing container for containing a developer, a developer carrier for carrying a developer, and an axial direction of the developer carrier. And a stirring member for stirring the developer in the developing container, and a magnet provided on the outside of the developing container along the rotation trajectory of the tip of the stirring member. I assume.

  According to the present invention, the flowability of the developer can be improved.

FIG. 2 is a cross-sectional explanatory view showing the configuration of the image forming apparatus. FIG. 2 is a block diagram showing a configuration of a control unit of the image forming apparatus. (A), (b) is perspective explanatory drawing which shows the internal structure of the image development apparatus of this embodiment. (C) is perspective explanatory drawing which shows the internal structure of the image development apparatus of a comparative example. FIG. 2A is a cross-sectional explanatory view cut in a direction orthogonal to the longitudinal direction of the developing device of the present embodiment. (B) is cross-sectional explanatory drawing cut | disconnected in the direction orthogonal to the longitudinal direction of the image development apparatus of a comparative example. It is perspective explanatory drawing which shows the structure of the upper edge part of the control wall of a conveyance path. It is a front view which shows the structure of a stirring member. (A) is a cross-sectional explanatory view showing the configuration of a developing device in which a magnet for guiding a developer is attached to the outer surface of a developing container. (B) is plane explanatory drawing which shows the structure of the image development apparatus which attached the magnet which induces a developing agent to the outer surface of the image development container. (A) is cross-sectional explanatory drawing which shows the structure of the other developing device which attached the magnet which induces a developing agent to the outer surface of a developing container. (B) is plane explanatory drawing which shows the structure of the other developing device which attached the magnet which induces a developing agent to the outer surface of a developing container. (A) is a top view which shows the shape of a magnet. (B) is a front view which shows the shape of a magnet. 5 is a flowchart showing developer supply control. It is a figure which shows magnetic force distribution in the longitudinal direction of the conveyance path of the magnet provided in the conveyance path. It is a figure which shows transition of the reflection density at the time of performing density | concentration detection to the printing surface after fixing by the present embodiment and a comparative example by a reflection type sensor.

  An embodiment of an image forming apparatus provided with a developing device according to the present invention will be specifically described with reference to the drawings. The dimensions, materials, shapes, relative positions, etc. of the components described in the following embodiments can be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions.

<Image forming apparatus>
The configuration of the image forming apparatus 6 provided with the developing device 114 according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional explanatory view showing the configuration of the image forming apparatus 6. FIG. 2 is a block diagram showing the configuration of the control unit 8 of the image forming apparatus 6. The image forming apparatus 6 shown in FIG. 1 has, for example, a photosensitive drum 112 which is an image carrier made of an organic photosensitive member. The surface of the photosensitive drum 112 rotating in the counterclockwise direction in FIG. 1 is uniformly charged by the charging roller 2 as charging means.

  A photosensitive drum 112 which emits laser light from a laser scanner 108 serving as an exposure unit based on the image information sent from the image signal processing unit 109 shown in FIG. 2 and uniformly charged via a polygon mirror and a reflection mirror (not shown). Expose the surface of the Thereby, an electrostatic latent image is formed on the surface of the photosensitive drum 112. The electrostatic latent image formed on the surface of the photosensitive drum 112 is supplied with a developer (toner) by a developing sleeve 114 a serving as a developer carrying member provided on the developing device 114 serving as a developing unit. . As a result, the toner image is developed on the surface of the photosensitive drum 112.

  The layer thickness of the developer carried on the surface of the developing sleeve 114a is regulated by the developer layer regulating member 114k when the developing sleeve 114a rotates in the clockwise direction in FIG. When a developer is supplied to the electrostatic latent image formed on the surface of the photosensitive drum 112 to develop as a developer image (toner image), a developing bias is applied to the developing sleeve 114 a from a developing bias power supply (not shown). . The developer carried on the surface of the developing sleeve 114 a by the potential difference formed between the developing sleeve 114 a to which the developing bias is applied and the surface of the photosensitive drum 112 forms an electrostatic latent image on the surface of the photosensitive drum 112. Fly towards. The flight of this developer is called development.

  On the other hand, a recording material such as paper stored in the feeding tray 7 is conveyed by a feeding unit (not shown) to a transfer nip N formed by the photosensitive drum 112 and the transfer roller 4 as a transfer unit. When a transfer bias is applied to the transfer roller 4 from a transfer bias power supply (not shown), the toner image carried on the surface of the photosensitive drum 112 is transferred to the recording material. The toner remaining on the surface of the photosensitive drum 112 without being transferred is scraped off and collected by a cleaning blade 22a provided in a cleaner 22 as a cleaning unit.

  The recording material to which the toner image has been transferred at the transfer nip portion N is conveyed to the fixing device 5 serving as a fixing unit, and the toner image is conveyed in the process of being nipped and conveyed by the heating roller and the pressure roller provided in the fixing device 5 It is heated, melted and heat-fixed to the recording material. The recording material on which the toner image is fixed is conveyed by a conveying unit (not shown) and discharged onto the discharge unit 9. An image is formed on the recording material by the image forming means. Reference numeral 40 shown in FIG. 1 denotes an image reading apparatus for reading an original image.

<Control unit>
Next, the configuration of the control unit 8 of the image forming apparatus 6 will be described with reference to FIG. As shown in FIG. 2, a ROM (Read Only Memory; read only memory) 101 as a storage means is connected to a CPU (Central Processing Unit; central processing unit) 100 as a control means. Further, a RAM (Randam Access Memory; random access memory) 102 serving as a storage unit is connected to the CPU 100. Further, to the CPU 100, a display unit 103, an image signal processing unit 109, a drive control unit 110, a detection unit 111, and the like are connected.

  The CPU 100 performs various arithmetic processing and the like. The ROM 101 also stores various control programs for image formation. In addition, various data and the like during execution of the control program are temporarily stored in the RAM 102. In addition, on the display unit 103, the operation state and operation message of the image forming apparatus 6, or the toner end state and the near end state are displayed.

  The detection unit 111 detects the developer in the conveyance path 114c that conveys the developer along the axial direction of the developing sleeve 114a (developer carrier) provided in the developing device 114 shown in FIG. 4A. A toner sensor 13 is provided. Further, the detection unit 111 is provided with a toner sensor 114 s for detecting the developer in the stirring chamber 20 provided in the developing device 114.

  The CPU 100 detects the developer remaining amount in the conveyance path 114 c and the developer remaining amount in the agitating chamber 20 based on the output voltages respectively output from the toner sensors 13 and 114 s. Further, the detection unit 111 includes an environment sensor 115 for detecting an environmental temperature and humidity in which the image forming apparatus 6 is installed, and a door for opening and closing a jam in the image forming apparatus 6 or replacement or maintenance of the toner bottle 50. A door open / close sensor 116 is provided to detect the open / close state of the door.

  The drive control unit 110 drives and controls the bottle motor 10 as a drive source for applying a rotational force to the toner bottle 50 via a drive gear (not shown) provided on the outer peripheral surface of the toner bottle 50 shown in FIG. 1. Further, the drive control unit 110 rotates a toner conveyance screw (not shown) rotatably provided inside the main body toner conveyance path 60 connecting the toner bottle 50 shown in FIG. 1 and the toner supply port 114 b of the developing device 114. Drive control as a power source to drive.

  A spiral blade 114d2 is provided on the outer peripheral surface of the rotation shaft 114d1 of the conveyance screw 114d, and the developer is conveyed by the rotation of the spiral blade 114d2. Furthermore, the drive control unit 110 controls driving of the main motor 3 as a drive source. The main motor 3 rotationally drives the photosensitive drum 112, the stirring member 114g rotatably provided around the rotation shaft 114g1 in the stirring chamber 20, and the developing sleeve 114a rotatably provided in the developing chamber 114i. The agitating member 114g is provided rotatably about the rotation shaft 114g1 along the axial direction of the developing sleeve 114a (developer carrying member), and agitates the developer in the agitating chamber 20 (in the developing container) of the developing container 114n. Do.

  The image signal processing unit 109 is connected to the image data acquisition unit 104, and converts the image data acquired from the image data acquisition unit 104 into a video signal. Then, this video signal is converted into a laser drive pulse and transmitted to the laser scanner 108. The image data acquisition unit 104 includes an image reading device 40 used for a copying function, a printer interface 106 for receiving image data output from an external device, and a modem 107 for receiving image data from a telephone network. ing. The image data capture unit 104 captures image data into the image forming apparatus 6 via these components.

<Developer>
Next, the developer used in the present embodiment will be described. The developer used in this embodiment is a magnetic one-component developer based on a pulverizing method and contains a magnetic material with a resin as a base material, and the developer particle size is about 5 μm to 10 μm, and the developer charge amount Is about -5 μC / g to -20 μC / g.

<Developer>
Next, the configuration of the developing device 114 according to the present invention will be described with reference to FIGS. 3 (a), 3 (b) and 4 (a). FIGS. 3A and 3B are perspective explanatory views showing the internal configuration of the developing device 114. FIG. FIG. 4A is a cross-sectional explanatory view cut in a direction orthogonal to the longitudinal direction of the developing device 114. FIG. As shown in FIGS. 3 (a), 3 (b) and 4 (a), the front end portion of the developing device 114 (below the FIGS. 3 (a), 3 (b), the left side of FIG. 4 (a)) A developing sleeve 114a as a developer carrier is rotatably provided.

  At the rear end portion of the developing device 114 (upper side in FIGS. 3A and 3B, right side in FIG. 4A), along the axial direction of the developing sleeve 114a (FIGS. 3A and 3B) (From the right side to the left side), the transport path 114c for transporting the developer is provided. As shown to Fig.4 (a), the bottom face 114c1 of the conveyance path 114c is formed in cross-sectional circular arc shape.

  A replenishing port 114b, which is an opening, is provided on the upstream side of the transport path 114c in the transport direction of the developer (right side in FIGS. 3A and 3B). Above the supply port 114b, as shown in FIG. 1, the discharge port of the main toner transport path 60 connected to the hopper 41 is connected. The developer supplied from the toner bottle 50 into the hopper 41 is transported by a transport screw (not shown) provided in the main toner transport path 60 and is supplied from the supply port 114 b of the transport path 114 c of the developing device 114 into the transport path 114 c. It is replenished.

<Developer supply operation>
Next, the developer replenishment operation will be described with reference to FIG. In step S1 of FIG. 10, the power of the main body of the image forming apparatus 6 is turned on. Then, in step S2, the user operates the operation unit 11 to start a normal image forming operation. Next, in step S3, the developing device 114 is driven to consume the developer in accordance with the image formation.

  Next, in step S4, the CPU 100 determines the presence or absence of the developer in the stirring chamber 20 based on the detection result of the toner sensor 114s that detects the developer remaining amount in the stirring chamber 20 of the developing device 114. In step S4, the toner sensor 114s detects that the developer is present in the stirring chamber 20. In that case, the process proceeds to step S5, and the CPU 100 determines the presence or absence of the developer in the hopper 41 based on the detection result of the toner sensor 41a that detects the developer remaining amount in the hopper 41.

  In step S5, the toner sensor 41a detects that there is no developer in the hopper 41. In that case, the process proceeds to step S7, and the CPU 100 causes the drive control unit 110 to rotationally drive the bottle motor 10 to supply the developer from the toner bottle 50 into the hopper 41, and then the CPU 100 ends the process.

  In step S5, when the toner sensor 41a detects that the developer is present in the hopper 41, the CPU 100 ends the process. In step S4, the toner sensor 114s detects that there is no developer in the stirring chamber 20. In that case, the process proceeds to step S6, and the CPU 100 rotationally drives the hopper motor 12 so that the supply port 114b provided in the developing device 114 from the hopper 41 via the main body toner conveyance path 60 enters the conveyance path 114c. Supply developer.

  Thereafter, the process proceeds to step S5, and the CPU 100 determines the presence or absence of the developer in the hopper 41 based on the detection result of the toner sensor 41a. If it is detected in step S5 that the developer in the hopper 41 is not present, the process proceeds to step S7, and the CPU 100 rotationally drives the bottle motor 10 to supply the developer from the toner bottle 50 into the hopper 41. End the process.

<Transport path>
Next, the configuration of the conveyance path 114c provided in the developing device 114 will be described with reference to FIGS. 3A, 3B, 4A, and 5. FIG. FIG. 5 is a perspective view showing the configuration of the upper edge portion 114f of the restriction wall 114e of the conveyance path 114c. As shown in FIGS. 3A and 3B, a conveyance screw 114d is provided in the conveyance path 114c provided in the developing device 114. The conveying screw 114d is disposed on the upstream side (the right side of FIGS. 3A and 3B) of the developer in the conveying direction on the side where the supply port 114b communicated with the conveying path 114c is provided. And (b) are configured as transport means for transporting the developer.

<Conveying screw>
The conveying screw 114d is provided with one continuous spiral blade 114d2 on the outer peripheral surface of the rotating shaft 114d1. The outer diameter of the spiral blade 114d2 is 16 mm, the outer diameter of the rotary shaft 114d1 is 6 mm, and the pitch of the spiral blade 114d2 along the rotary shaft 114d1 is 20 mm. The spiral blade 114d2 is an inclined surface, and the inclination angle between the outer surface of the spiral blade 114d2 and the outer peripheral surface of the rotation shaft 114d1 is 108 °.

  The CPU 100 rotationally drives the conveyance path motor 113 by the drive control unit 110 to rotate the rotation shaft 114d1 of the conveyance screw 114d. As a result, the developer supplied from the supply port 114b into the transport path 114c moves from the upstream side (the right side of FIGS. 3A and 3B) in the developer transport direction as the spiral blade 114d2 rotates. The sheet is transported toward the left side of FIGS. 3 (a) and 3 (b).

  The developing sleeve 114 a of the developing device 114 is rotationally driven by the main motor 3 via a clutch. The stirring member 114g provided in the developing container 114n and the conveying screw 114d are connected to the developing sleeve 114a via a plurality of gears (not shown), and the stirring member 114g and the conveying screw 114d also rotate as the developing sleeve 114a rotates. To drive.

  The developer in the transport path 114c is transported along the axial direction of the developing sleeve 114a by rotation of the transport screw 114d. The developer in the middle of the conveyance in the conveyance path 114c passes over the upper edge portion 114f of the restriction wall 114e of the conveyance path 114c and falls into the stirring chamber 20.

<Restricted wall>
Next, the configuration of the restriction wall 114e will be described with reference to FIG. As shown in FIG. 5, at the edge of the front end side (the lower side of FIGS. 3A and 3B and the left side of FIG. 4A) of the transport path 114c where the developer drops, development of the transport path 114c is performed. A regulating wall 114e is provided to rise upward along the agent transport direction. On the regulating wall 114e, an upper edge portion 114f that regulates the amount of developer falling (the amount of developer) falling from the conveyance path 114c into the stirring chamber 20 along the developer conveyance direction of the conveyance path 114c. It is provided.

  As shown in FIG. 5, the upper edge portion 114f of the regulating wall 114e is inclined such that its height gradually decreases from the upstream side to the downstream side in the developer transport direction of the transport path 114c. The surface width W of the upper edge portion 114f of the transport path 114c (width of the surface in the front-rear direction orthogonal to the transport direction of the developer) is gradually expanded from the upstream side to the downstream side in the transport direction of the developer. It is formed. As a result, the upper edge portion 114f of the regulating wall 114e is higher on the upstream side (right side in FIG. 5) in the developer transport direction, lower on the downstream side (left side in FIG. 5), and the regulating wall becomes lower. The surface width W of the upper edge portion 114f of 114e is formed to be wide.

<Agitating member>
Next, the configuration of the stirring member 114g will be described with reference to FIG. FIG. 6 is a front view showing the structure of the stirring member 114g. The stirring member 114g shown in FIG. 6 has a rotating shaft 114g1 formed of a resin and a sheet-like stirring blade 114g4 provided with a plurality of V-shaped slits 114g2 and 114g3 consisting of through holes bonded with a double-sided tape Is configured.

  In the stirring blade 114g4, a plurality of V-shaped slits 114g2 and 114g3 arranged in a projecting shape are arranged at predetermined intervals from the left and right ends to the central portion of the stirring blade 114g4 in the longitudinal direction. The stirring member 114g conveys the developer to the developing chamber 114i provided with the developing sleeve 114a while stirring the developer in the stirring chamber 20 by the stirring blade 114g4 by rotating around the rotation shaft 114g1 as a rotation center. The stirring member 114g is configured such that the tip portion 114g5 of the stirring blade 114g4 passes near the inner wall of the stirring chamber 20 when it is rotated. Alternatively, the agitating member 114g may be configured such that the tip 114g5 of the agitating blade 114g abuts and slides on the inner wall of the agitating chamber 20 when rotating.

<Magnet>
Next, with reference to FIGS. 7 to 9, the configuration of the magnet 114h housed in the stirring chamber 20 and guiding the transport direction of the developer stirred and transported by the stirring member 114g will be described by the attraction force of the magnetic force. FIG. 7A shows a developing device 114 in which a magnet 114h for attracting and guiding the developer made of a magnetic material by magnetic force is attached to the outer surface 114n1 (outside) of the developing container 114n corresponding to the stirring chamber 20 containing the developer. It is cross-sectional explanatory drawing which shows the structure of. FIG. 7B shows a developing device 114 in which a magnet 114h for attracting and guiding the developer made of a magnetic material by magnetic force is attached to the outer surface 114n1 (outside) of the developing container 114n corresponding to the stirring chamber 20 containing the developer. It is plane explanatory drawing which shows the structure of.

  FIG. 8A shows another development in which a magnet 114h for attracting and guiding the developer made of a magnetic material by magnetic force is attached to the outer surface 114n1 (outside) of the developing container 114n corresponding to the stirring chamber 20 containing the developer. FIG. 14 is a cross-sectional explanatory view showing the configuration of the device 114. FIG. 8B shows another development in which a magnet 114h for attracting and guiding the developer made of a magnetic material by magnetic force is attached to the outer surface 114n1 (outside) of the developing container 114n corresponding to the stirring chamber 20 containing the developer. FIG. 6 is a plan view showing the configuration of the device 114. FIGS. 9A and 9B are a plan view and a front view showing the shape of the magnet 114h.

  The developer used in the present embodiment is a magnetic one-component developer and contains a magnetic material with a resin as a base material. For this reason, the developer made of a magnetic substance is attracted by the magnetic force of the magnet 114h to induce the transport direction. The magnet 114h is provided on the outer surface 114n1 (outside) of the developing container 114n along the rotation trajectory 1 of the tip portion 114g5 of the agitating blade 114g4 of the agitating member 114g rotatably provided around the rotary shaft 114g1 in the agitating chamber 20. Be

  The magnet 114h of the present embodiment employs a permanent magnet such as a nylon ferrite magnet. The magnet 114 h shown in FIGS. 9A and 9B is made of a nylon ferrite magnet. As shown in FIG. 9A, the magnet 114h has a length of 310 mm in the longitudinal direction and a width of 5 mm. Furthermore, as shown in FIG. 9B, in the longitudinal direction of the magnet 114h, the height of the higher end 114h2 is set to 10 mm, and the height of the lower end 114h3 is set to 2 mm.

  As shown in FIGS. 7 and 8, the magnet 114h shown in FIGS. 9A and 9B is a member of the developing container 114n that constitutes the stirring chamber 20 along the direction of the rotation shaft 114g1 of the stirring member 114g of the developing container 114n. Attach to the outer surface 114n1. At that time, as shown in FIGS. 7A and 7B and FIGS. 8A and 8B, the longitudinal direction of the magnet 114h corresponds to the rotational direction of the stirring member 114g (FIGS. 7B and 8). (B) is inclined at a predetermined angle θ with respect to the vertical direction). In the present embodiment, the angle θ is set to 45 degrees.

  The stirring member 114g of the present embodiment rotates in the clockwise direction of FIGS. 7A and 8A about the rotation shaft 114g1. The magnet 114h of this embodiment is provided on the outer surface 114n1 of the agitating chamber 20 of the developing container 114n, as shown in FIGS. 7 (a) and 7 (b) and FIGS. 8 (a) and 8 (b).

  The magnet 114h arranges the higher end 114h2 of the magnet 114h on the upstream side of the agitating member 114g in the rotational direction (the upper side in FIGS. 7B and 8B). Then, the lower end 114h3 of the magnet 114h is disposed on the downstream side of the stirring member 114g in the rotational direction (the lower side in FIGS. 7B and 8B). As a result, in the magnet 114h, the magnetic force on the upstream side (the upper side in FIGS. 7B and 8B) in the rotational direction of the agitating member 114g is strong, and the downstream side in the rotational direction of the agitating member 114g (FIG. 7B and FIG. The magnetic force is set to become weaker toward the lower side of 8 (b).

  The magnetic force of the magnet 114 h of the present embodiment generates a magnetic force of about 1 mT or more and 20 mT or less at a position 20 mm away from the outer surface 114 n 1 of the developing container 114 n constituting the stirring chamber 20. The distance from the surface 114h1 on the outer surface 114n1 side of the developing container 114n of the magnet 114h to the position separated 20 mm from the outer surface 114n1 of the developing container 114n constituting the agitating chamber 20 is 20 mm.

  FIG. 11 is a diagram showing the magnetic force distribution in the longitudinal direction of the magnet 114 h. In the present embodiment, as shown by the graph a in FIG. 11, the magnetic force in the vicinity of the higher end portion 114h2 of the magnet 114h is 10 mm apart from the outer surface 114n1 of the developing container 114n constituting the agitating chamber 20 by 20 mm. It is 5mT in position. The magnetic force in the vicinity of the lower end 114h3 of the height of 2 mm of the magnet 114h is 2 mT at a position 20 mm away from the outer surface 114n1 of the developing container 114n constituting the agitating chamber 20.

  The developer replenished from the replenishing port 114b into the conveyance path 114c drops into the agitating chamber 20 over the upper edge portion 114f of the regulating wall 114e. The developer contained in the agitating chamber 20 is agitated and conveyed by an agitating member 114g which rotates around a rotating shaft 114g1. At this time, the developer made of a magnetic material is attracted by the magnetic force of the magnet 114h to guide the developer in the transport direction.

<Mounting position of magnet>
Next, with reference to FIGS. 7 and 8, the mounting position of the magnet 114h for guiding the transport direction of the developer in the stirring chamber 20 will be described. The stirring member 114g of the present embodiment rotates in the clockwise direction of FIGS. 7A and 8A about the rotation shaft 114g1. The magnet 114h of this embodiment is provided on the outer surface 114n1 of the agitating chamber 20 of the developing container 114n, as shown in FIGS. 7 (a) and 7 (b) and FIGS. 8 (a) and 8 (b).

  The magnet 114h is directed from the upstream side (the upper side in FIGS. 7B and 8B) to the downstream side (the lower side in FIGS. 7B and 8B) of the stirring member 114g in the rotational direction. It arrange | positions so that the magnetic force of the magnet 114h may become low gradually. The longitudinal direction of the magnet 114 h is set at an angle θ of 45 degrees with respect to the rotational direction of the stirring member 114 g (vertical direction in FIGS. 7B and 8B).

  3 (a), 7 (a), and 7 (b), two magnets 114h are parallel to the outer surface 114n1 of the agitating chamber 20 of the developing container 114n only from the center to the upstream side in the developer transport direction of the transport path 114c. It is an example arranged at A higher end portion 114h2 of 10 mm in height of the magnet 114h is provided on the upstream side of the transport path 114c in the transport direction of the developer (right side in FIG. 7B). Then, the lower end portion 114h3 of 2 mm in height of the magnet 114h is provided on the downstream side of the transport direction of the developer on the transport path 114c (left side in FIG. 7B).

  As shown in FIGS. 3B and 8A and 8B, the inclination direction of the magnet 114h on the upstream side from the center in the developer transport direction of the transport path 114c is considered. Also, the inclination direction of the magnet 114h on the downstream side from the center in the developer transport direction of the transport path 114c is considered. The inclination directions of the two magnets 114h are arranged symmetrically with respect to the central portion of the transport path 114c in the transport direction of the developer.

  That is, as shown in FIGS. 3B and 8A and 8B, the magnet 114h on the upstream side from the center in the developer transport direction of the transport path 114c is considered. Similar to FIGS. 7A and 7B, the magnet 114h is an outer surface of the stirring chamber 20 of the developing container 114n on the upstream side (right side of FIG. 8B) from the center in the developer transport direction of the transport path 114c. Two rows of magnets 114h were arranged in parallel in 114n1.

  At this time, the magnet 114h is provided with the higher end portion 114h2 having a height of 10 mm on the upstream side (right side in FIG. 8B) of the transport path 114c in the developer transport direction. Further, a lower end portion 114h3 having a height of 2 mm is provided on the downstream side of the transport direction of the developer on the transport path 114c (left side in FIG. 8B).

  Furthermore, two magnets 114h are disposed in parallel on the outer surface 114n1 of the agitating chamber 20 of the developing container 114n also from the center to the downstream side in the developer transport direction of the transport path 114c. The magnet 114h on the downstream side from the center in the developer transport direction of the transport path 114c is considered. The magnet 114h is provided with a higher end portion 114h2 having a height of 10 mm on the downstream side (left side in FIG. 8B) of the transport path 114c in the developer transport direction. A lower end portion 114h3 having a height of 2 mm is provided on the upstream side of the transport path 114c in the developer transport direction (right side in FIG. 8B).

  As shown in FIGS. 7 (a) and 7 (b) and FIGS. 8 (a) and 8 (b), the magnetic substance is made of magnetic material by the attraction force of the magnet 114h provided on the outer surface 114n1 of the agitating chamber 20 of the developing container 114n. Deriving the transport direction of the developer.

  The developer replenished from the replenishing port 114b of the conveyance path 114c falls into the agitating chamber 20 over the upper edge portion 114f of the regulating wall 114e. Thereafter, the developer accommodated in the stirring chamber 20 is stirred and conveyed by the stirring member 114g which rotates in the clockwise direction of FIGS. 7A and 8A around the rotation shaft 114g1. The conveying direction of the developer made of a magnetic material contained in the stirring chamber 20 is attracted and guided by the magnetic force of each magnet 114h. The suction force by the magnetic force of each magnet 114h acts in the direction of reinforcing the transport force of the developer made of a magnetic material that is stirred and transported by the stirring member 114g, and also makes the developer in the stirring chamber 20 uniform.

  7 (a) and 7 (b), the magnetic force of the magnet 114h provided on the outer surface 114n1 of the agitating chamber 20 of the developing container 114n attracts the developer made of the magnetic material contained in the agitating chamber 20. Works. The developer concentrates in the stirring chamber 20 beyond the upper edge portion 114f of the regulating wall 114e on the upstream side (right side in FIG. 7B) of the developer transport direction (the right side of FIG. 7B) provided with the replenishment port 114b of the transport path 114c. Fall down. At this time, the developer made of a magnetic material is guided by the magnetic force of the magnet 114h toward the downstream side of the transport direction of the developer on the transport path 114c (left side in FIG. 7B). Thereby, the developer in the stirring chamber 20 can be made uniform.

  In the outer surface 114n1 of the stirring chamber 20 of the developing container 114n shown in FIGS. 8A and 8B, the stirring chamber is generated by the magnetic force of the magnet 114h provided on the upstream side from the center in the developer transport direction of the transport path 114c. A suction force acts on the developer made of a magnetic material accommodated in the inside of the unit 20. The developer concentrates in the stirring chamber 20 beyond the upper edge portion 114f of the regulating wall 114e on the upstream side (right side in FIG. 8B) of the developer transport direction (the right side of FIG. 8B) provided with the replenishment port 114b of the transport path 114c. Fall down. At this time, the developer made of a magnetic material is guided by the magnetic force of the magnet 114h toward the downstream side of the transport direction of the developer on the transport path 114c (left side in FIG. 8B). Thereby, the developer in the stirring chamber 20 can be made uniform.

  On the other hand, by the magnetic force of the magnet 114h provided on the downstream side (left side in FIG. 8B) from the center in the developer transport direction of the transport path 114c, the developer made of magnetic material stored in the stirring chamber 20 is attracted Force works. The suction force is concentrated on the developer falling in the stirring chamber 20 over the upper edge portion 114f of the regulating wall 114e on the downstream side of the transport direction of the developer on the transport path 114c (left side in FIG. 8B). The developer is guided toward the upstream side (the right side of FIG. 8B) in the transport direction of the developer on the transport path 114c. Thereby, the developer in the stirring chamber 20 can be made uniform.

<Comparison of image density>
Next, the comparison of the image density by the developing device 114 of the comparative example and the present embodiment will be described using FIG. Graph b of FIG. 12 shows the change of the image density by the developing device 114 of the comparative example. In the developing device 114 of the comparative example, as shown in FIGS. 3C and 4B, the magnet 114h is not provided on the outer surface 114n1 of the agitating chamber 20 of the developing container 114n. Graph c in FIG. 12 shows a change in image density by the developing device 114 of the present embodiment. As shown in FIGS. 3B, 4A, and 8, the developing device 114 of the present embodiment is provided with a magnet 114h on the outer surface 114n1 of the agitating chamber 20 of the developing container 114n.

  The reflection density of the print surface of the recording material after the toner image is fixed by the fixing device 5 by the developing device 114 of the comparative example and the developing device 114 of this embodiment is compared by the reflection type sensor. . Graph b of FIG. 12 is a diagram showing the transition of the reflection density when the density of the printing surface of the recording material after the toner image is fixed by the fixing device 5 is detected by the reflection type sensor, and the number of durable sheets in the comparative example. . Graph c in FIG. 12 shows the toner image formed on the recording material when the density of the printing surface of the recording material after fixing the toner image by the fixing device 5 is detected by the reflection type sensor according to the present embodiment. It is a figure which shows transition of the reflection density of. In the present embodiment, a reflection densitometer manufactured by X-Rite was used.

  As shown in graph b of FIG. 12, in the developing device 114 of the comparative example, the initial reflection density at which the image forming operation was started by the image forming device 6 was around 1.50. Further, the reflection density decreased to around 1.10 when reaching the endurance number of 60000 sheets (printing of 60000 sheets of an image having a printing ratio of 5% for black single color on A4 size recording material).

  On the other hand, as shown by the graph c in FIG. 12, in the developing device 114 of this embodiment, the initial reflection density at which the image forming operation was started by the image forming device 6 was 1.50. Further, the reflection density was about 1.20 at the time of reaching the endurance number of 60000 sheets (printing of 60000 sheets of an image having a printing ratio of 5% for black single color on an A4 size recording material). As a result, it can be seen that in the developing device 114 of the present embodiment shown by the graph c of FIG. 12, the reduction in density is improved more than the developing device 114 of the comparative example shown by the graph b of FIG.

  In the developing device 114 of the present embodiment, the magnet 114h is provided on the outer surface 114n1 of the agitating chamber 20 of the developing container 114n. The developer replenished from the replenishing port 114b of the conveyance path 114c falls into the agitating chamber 20 over the upper edge portion 114f of the regulating wall 114e. Thereafter, the developer accommodated in the agitating chamber 20 is stirred and conveyed by the agitating member 114g which rotates around the rotating shaft 114g1. At this time, the developer made of a magnetic substance is attracted by the magnetic force of the magnet 114 h to induce the transport direction.

  The magnet 114h is directed from the upstream side (upper side in FIGS. 7B and 8B) to the downstream side (lower side in FIGS. 7B and 8B) of the stirring member 114g in the rotational direction. The magnetic force of 114 h is set to be gradually lowered. The magnet 114h on the upstream side (right side in FIGS. 7B and 8B) of the center in the developer transport direction of the transport path 114c is considered. At this time, in the longitudinal direction of the magnet 114h, the end 114h3 having a height of 2 mm and a weak magnetic force is disposed on the central side (inner side) in the longitudinal direction of the developing container 114n than the end 114h2 having a height of 10 mm and a strong magnetic force. Be done.

  The developer made of a magnetic material contained in the stirring chamber 20 is attracted to the bottom surface 20 a side of the stirring chamber 20 by the magnetic force of the magnet 114 h and is restrained. The stirring member 114g rotates in the clockwise direction in FIGS. 7A and 8A about the rotation shaft 114g1. At that time, the developer attracted and constrained by the magnetic force of the magnet 114h toward the bottom surface 20a of the stirring chamber 20 is swept by the stirring member 114g toward the developing chamber 114i in which the developing sleeve 114a is provided. At this time, the developer in the stirring chamber 20 is attracted to the bottom surface 20a of the stirring chamber 20 by the magnetic force of the magnet 114h and swept by the stirring member 114g while being restrained.

  The tip portion 114g5 of the stirring blade 114g4 of the stirring member 114g passes through the position of the end 114h3 on the downstream side of the rotation direction of the stirring member 114g in the longitudinal direction of the magnet 114h. After that, the developer which has been attracted and restrained to the bottom surface 20a side of the stirring chamber 20 by the magnetic force of the magnet 114h is agitated after being released from the magnetic force of the magnet 114h.

  Thus, the developer made of a magnetic material is attracted and restrained by the magnetic force of the magnet 114h attached to the outer surface 114n1 of the agitating chamber 20 of the developing container 114n. Then, a force is generated to transport the developer stirred and conveyed by the stirring blade 114g4 of the stirring member 114g along the longitudinal direction of the magnet 114h. As a result, a force for transporting the developer in the stirring chamber 20 along the longitudinal direction of the magnet 114h is generated along with the developer carrying force by the rotation of the stirring member 114g, and the developer in the stirring chamber 20 is made uniform. Can be stirred.

  In addition, it is possible to set the direction in which the developer is easily transported using the magnetic force of the magnet 114h within the rotation locus along which the agitating blade 114g4 in the developing container 114n rotates. Further, the movement resistance of the developer is adjusted within the rotation locus in which the agitating blade 114g4 in the developing container 114n rotates using the magnetic force of the magnet 114h, thereby promoting the movement of the agitating member 114g in the direction of the rotating shaft 114g1. can do. As a result, even if the amount of developer dropped into the agitating chamber 20 exceeds the upper edge portion 114f of the regulating wall 114e of the transport path 114c, the developer in the agitating chamber 20 is reliably stirred and transported. It is possible to prevent the deterioration of the developer in the developing container 114n.

  In the present embodiment, an example in which a nylon ferrite magnet is adopted as the magnet 114h that attracts and restrains the developer by magnetic force has been described. In addition, a plurality of magnets having different magnetic forces can be disposed on the outer surface 114n1 of the agitating chamber 20 of the developing container 114n in the direction of the rotation shaft 114g1 (rotational shaft direction) of the stirring member 114g. At this time, a magnet with strong magnetic force is disposed on the upstream side of the stirring member 114g in the rotational direction (the upper side in FIGS. 7B and 8B), and the downstream side (FIGS. 7B and 8B). Place the magnet with weak magnetic force on the lower side). Then, the magnetic force of these magnets can be used to align the developer made of a magnetic body in the direction of leading the central portion in the direction of the rotation shaft 114g1 of the agitating member 114g.

  In addition, an electromagnet capable of adjusting the magnetic force is disposed on the outer surface 114n1 of the agitating chamber 20 of the developing container 114n along the rotational direction of the agitating member 114g. Then, the developer made of a magnetic material may be disposed in the direction of leading toward the central portion in the direction of the rotation shaft 114g1 of the agitating member 114g by the magnetic force of the electromagnet.

  Further, as shown in FIG. 7B, the magnet 114h may be provided at least on the upstream side (right side of FIG. 7B) in the developer transport direction of the transport path 114c. Alternatively, the magnet 114h may be provided only on the upstream side (right side in FIG. 7B) of the transport path 114c in the developer transport direction on the outer surface 114n1 of the stirring chamber 20 of the developing container 114n.

1 ... Rotation locus 114 ... Development device 114a ... Development sleeve (developer carrier)
114 g ... stirring member 114 g 4 ... stirring blade 114 g 5 ... tip part 114 h ... magnet 114 n ... developing container 114 n 1 ... outer surface (outside)

Claims (7)

A developer container for containing a developer;
A developer carrier that carries a developer;
An agitation member provided rotatably along the axial direction of the developer carrier and agitating the developer in the developer container;
A magnet provided on the outside of the developer container along the rotation trajectory of the tip of the stirring member;
And a developing device characterized by comprising:   The developing device according to claim 1, wherein the magnet is inclined at a predetermined angle with respect to the rotation direction of the stirring member in the longitudinal direction.   The developing apparatus according to claim 1 or 2, wherein the magnet has a strong magnetic force on the upstream side in the rotation direction of the stirring member and a magnetic force decreases toward the downstream side in the rotation direction of the stirring member. apparatus.   The developing device according to any one of claims 1 to 3, wherein a plurality of the magnets are arranged in the rotational axis direction of the stirring member.   The developing device according to any one of claims 1 to 4, wherein the magnet comprises a plurality of magnets having different magnetic forces.   The developing device according to any one of claims 1 to 5, wherein the magnet is an electromagnet. The developing device according to any one of claims 1 to 6.
An image forming unit that forms an image on a recording material;
An image forming apparatus comprising:

Images