JP5374899B2 - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device, capable of making the amount of developer conveyed to a developer supply port stable and to provide an image forming apparatus. <P>SOLUTION: The developing device 58 includes a toner storage chamber 102 storing toner T; a developing unit 72; and a toner transport path 114. In the toner transport path 114, a toner inflow port 118 and a toner supply port 120 are formed and a transport auger 116 is provided in internals, wherein the toner transport path 114 is arranged so as to be parallel with the direction of feeding the developer G by a first auger 86 and a second auger 88, and the height position of the toner supply port 120 is higher than the bottom part B on the side of the toner inflow port 118 of the toner transport path 114. Because of this, in the toner transport path 114, the toner T on the side of the toner inflow port 118 is in the highest density state. Thus, the occurrence of a part where the density of the toner T is low on the way of the toner transport path 114 is prevented, to make the amount of the toner T transported to the toner supply port 120 stable. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

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

  2. Description of the Related Art Conventionally, some image forming apparatuses such as printers and copiers are provided with a conveying unit that conveys toner from a toner containing unit containing toner to a developing unit that performs development (see, for example, Patent Documents 1 to 3) ).

  In the image forming apparatus of Patent Document 1, a screw auger is provided as a toner conveying means, and the screw auger is rotated to convey toner in the axial direction. The remaining amount of toner conveyed is detected by a toner remaining amount detection sensor.

  In the image forming apparatus of Patent Document 2, the developing unit includes a developer accommodating chamber and a toner replenishing chamber, and a dispensing member is provided as a toner conveying means in a dispensing chamber connecting the toner replenishing chamber and the developer accommodating chamber.

In the image forming apparatus disclosed in Patent Document 3, a small slit-shaped toner supply port is formed in the transport unit as a toner transport unit that transports toner from the toner storage unit to the toner supply unit of the developing device.
JP2001-083802 JP 2006-267933 A JP2003-241498

  In each of the image forming apparatuses disclosed in Patent Documents 1 to 3, the toner conveyance path extends in the horizontal direction, and the toner is not positively stored on the upstream side of the toner conveyance path.

  An object of the present invention is to obtain a developing device and an image forming apparatus in which the amount of developer transported to a developer supply port is stable.

The developing device according to claim 1 of the present invention includes a developer accommodating portion that accommodates a developer, a developer agitating member that agitates the developer sent from the developer accommodating portion, and the developer agitating member. A developer holding member that holds the agitated developer and supplies the developer to the photosensitive member; a developer inlet through which the developer flows from the developer accommodating portion; and an inflow from the developer inlet A developer supply port for supplying the developed developer to the developing unit, and a developer transport member provided with a developer transport member for transporting the developer from the developer inflow port to the developer supply port And the developer transport path is arranged in parallel with the developer feeding direction of the developer stirring member, and the position of the lower end portion of the developer supply port is the developer transport path Higher than the lowest part on the developer inlet side of the path, the developer conveying member is A first transport unit that transports the developer in a forward direction from the developer inflow port to the developer supply port toward the developer supply port, and development in a direction opposite to the forward direction toward the developer supply port A second transport unit that transports the developer, and the first transport unit is configured to transfer the developer downstream in the forward direction from an intermediate position between the developer inflow port and the developer supply port. The transport speed is configured to be slower than the upstream side, and the second transport unit is configured such that the transport speed of the developer in the facing region facing the developer supply port is higher than the intermediate position. It is configured to be slower than the developer conveyance speed of the conveyance unit.

In the developing device according to a second aspect of the present invention, the first transport unit and the second transport unit have spiral blades, and the spirals of the first transport unit and the second transport unit in the facing region. The pitch of the blades is narrower than the pitch of the spiral blades of the first transport unit on the upstream side of the intermediate position.

  In the developing device according to a third aspect of the present invention, the developer transport path is inclined at a constant gradient from the developer inlet to the developer supply port.

  In the developing device according to a fourth aspect of the present invention, the developer accommodating portion can be attached to and detached from the developer conveyance path.

  An image forming apparatus according to a fifth aspect of the present invention comprises: a latent image forming unit that forms a latent image of an image on the photosensitive member; and the developing device according to any one of the first to fourth aspects. And the developer holding member supplies the developer to the latent image for development.

  According to the first aspect of the present invention, as compared with the case where the present configuration is not provided, it is possible to suppress the occurrence of a portion where the density of the developer is sparse in the middle of the developer conveyance path, and development to the developer supply port. The transport amount of the agent is stable.

  According to the second aspect of the present invention, the developer is likely to stay in the vicinity of the developer supply port, and the developer can be stably supplied to the developing unit as compared with the case where the present configuration is not provided.

  The invention according to claim 3 makes it easier to process the developer conveyance path as compared with the case where this configuration is not provided.

  According to the fourth aspect of the present invention, the replacement of the developer is facilitated as compared with the case where the developer containing portion to the developing portion are integrated.

  According to the fifth aspect of the present invention, fluctuations in the amount of developer supplied to the developing section can be suppressed and stable image formation can be performed as compared with the case where this configuration is not provided.

  A developing device and an image forming apparatus according to a first embodiment of the invention will be described with reference to the drawings.

  FIG. 1 shows a printer 10 as an image forming apparatus of the present invention. In the printer 10, image forming units 12Y, 12M, 12C, and 12K that perform full color image formation using four color toners (yellow (Y), magenta (M), cyan (C), and black (K)) are arranged in the vertical direction. Has been. Each of the image forming units 12Y, 12M, 12C, and 12K has the same configuration except for the accommodated toner.

  Note that when distinguishing each color of yellow, magenta, cyan, and black, Y, M, C, and K are added after the code. However, if there is no need to distinguish each color, Y, M, C, and K are omitted. The toners Y, M, C, and K are not particularly limited by the manufacturing method, and various toners can be used.

  For example, as a toner manufacturing method, a binder resin, a colorant, a release agent, and a kneading and pulverizing method in which a charge control agent and the like are kneaded, pulverized, and classified, and particles obtained by a kneading and pulverizing method To change the shape by mechanical impact force or thermal energy, emulsion polymerization of a polymerizable monomer of the binder resin, and the formed dispersion, colorant, release agent, and charge control agent as required The emulsion polymerization aggregation method to obtain toner particles by mixing and agglomerating and heat-fusing with a dispersion liquid, a polymerizable monomer and a colorant, a release agent, and a charge control if necessary Suspension polymerization method in which a solution such as an agent is suspended in an aqueous solvent for polymerization, a binder resin and a colorant, a release agent, and if necessary, a solution such as a charge control agent is suspended in an aqueous solvent for granulation The dissolution suspension method can be used.

  In addition, a known method such as a production method in which the toner obtained by the above method is used as a core and agglomerated particles are further adhered and heat-fused to have a core-shell structure can be used. From the viewpoint, a suspension polymerization method, an emulsion polymerization aggregation method, and a dissolution suspension method produced with an aqueous solvent are preferable, and an emulsion polymerization aggregation method is particularly preferable. The toner base material includes a binder resin, a colorant, and a release agent. If necessary, silica or a charge control agent may be used.

  As the binder resin used, styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate, Α-methylene aliphatic monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Homopolymers and copolymers such as vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone. In particular, typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene-anhydride maleate. Examples thereof include acid copolymers, polyethylene, and polypropylene. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

  In addition, toner colorants include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachite green oxa. Rate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative one.

  Typical examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, Fischer tropic wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  In addition, a charge control agent may be added to the toner as necessary. Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used.

  When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner in the present invention may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  The toner used in the present invention can be produced by mixing the toner particles and the external additive with a Henschel mixer or a V blender. In addition, when the toner particles are produced by a wet method, external addition can be performed by a wet method.

  Lubricating particles added to the toner used in the present invention include solid lubricants such as graphite, molybdenum disulfide, talc, fatty acids, fatty acid metal salts, low molecular weight polyolefins such as polypropylene, polyethylene, and polybutene, and softening by heating. Aliphatic amides such as pointed silicones, oleic amides, erucic acid amides, ricinoleic acid amides, stearic acid amides, carnauba wax, rice wax, candelilla wax, wood wax, jojoba oil etc. Minerals such as plant waxes, animal waxes such as beeswax, montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc. Used alone Luke, or it may be used in combination.

  Other inorganic oxides added to the toner are small-diameter inorganic oxides with a primary particle size of 40 nm or less for powder flowability, charge control, etc. It is preferable to add a large-diameter inorganic oxide.

  These inorganic oxide fine particles may be known ones, but it is preferable to use silica and titanium oxide in combination for precise charge control. Further, the surface treatment of the small-diameter inorganic fine particles increases the dispersibility and increases the effect of increasing the powder fluidity.

  The color toner for electrophotography is used by mixing with a carrier, and as the carrier, iron powder, glass beads, ferrite powder, nickel powder or those having a resin coating on the surface thereof are used. The mixing ratio with the carrier can be set as appropriate.

  As shown in FIG. 1, a paper feed cassette 14 in which recording paper P is stored is provided at the bottom of the printer 10. In the vicinity of the paper feed cassette 14, a pickup roll 16 that feeds the recording paper P at a predetermined timing is provided. A paper transport path 22 including a transport roll 18 and a resist roll 20 is provided on the downstream side of the pickup roll 16 in the transport direction of the recording paper P. Here, the recording paper P sent out from the paper feed cassette 14 by the pickup roll 16 is sent to the paper transport path 22 through the transport roll 18 and the registration roll 20, and transports the recording paper P to each image forming unit 12. It is transported to the transport device 24.

  The image forming unit 12 is arranged in the order of the above-described Y, M, C, and K colors from the upstream side of the sheet conveyance path 22, and the image forming unit 12 is scanned on the left side of the image forming unit 12 in the drawing. An exposure device 26 for irradiating light is provided.

  In the exposure device 26, a semiconductor laser (not shown), a polygon mirror 30, an imaging lens 32, and a mirror 34 are disposed in a housing 28. Light from the semiconductor laser is deflected and scanned by the polygon mirror 30 to form an image. Each photoconductor 36 is irradiated through a lens 32 and a mirror 34. As a result, an electrostatic latent image corresponding to the image information is formed on the photoreceptor 36.

  Further, on the right side of the printer 10 in the drawing (position facing the photoconductor 36), the above-described transport device 24 is disposed. The conveying device 24 includes a pair of tension rolls 38 and 40 provided along the side wall 10 </ b> A of the printer 10, and a conveyance belt 42 wound around the tension rolls 38 and 40. The tension roll 40 is rotated by a motor (not shown) so that the conveyor belt 42 moves. A suction roll 44 is disposed in the vicinity of the tension roll 38, and a voltage is applied to the suction roll 44 so that the recording paper P is electrostatically attracted to the transport belt 42. ing.

  In addition, transfer rolls 46 are disposed at positions facing the photoconductors 36 of the respective colors on the back surface of the transport belt 42. By the transfer roll 46, the toner image on the photoreceptor 36 is transferred onto the recording paper P conveyed by the conveyance belt 42. The recording paper P onto which the toner image has been transferred is fixed by the action of heat and pressure by a fixing device 48 provided above the stretching roll 40. Then, the recording paper P on which the toner image is fixed is discharged to a discharge tray 52 by a discharge roll 50.

  In the vicinity of the exposure device 26 (left side in the figure), a control unit 54 that controls the operation of each unit of the printer 10 is provided.

  Next, the developing device 58 according to the first embodiment of the present invention will be described.

  As shown in FIG. 2A, the image forming unit 12 includes a photoconductor unit 56 (upper part) having a photoconductor 36, toner of each color, and an electrostatic latent image formed on the photoconductor 36. The image forming apparatus includes a developing device 58 (lower part) that develops each color toner on the image. An optical path 59 through which the exposure light L passes is formed between the photoconductor unit 56 and the developing device 58 so that the exposure light L is irradiated onto the surface of the photoconductor 36 through the optical path 59. It has become.

  The photoconductor unit 56 includes a photoconductor 36, a charging roll 60 that is disposed around the photoconductor 36 and charges the surface of the photoconductor 36 with a predetermined potential difference, a cleaning device 62 that cleans the surface of the photoconductor 36, and a photoconductor. An erase lamp 64 for neutralizing the surface of 36 and a sub-toner supply unit 66 disposed in the lateral direction of the cleaning device 62 are integrally configured.

  The sub-toner supply unit 66 is provided with an agitating and conveying member 68 having a mylar film for agitating and conveying the toner. Further, a support protrusion 70 projects from the side wall of the sub toner supply unit 66, and the image forming unit 12 is mounted on the printer 10 by inserting the support protrusion 70 into a receiving portion (not shown) in the printer 10. It is like that.

  On the other hand, as shown in FIG. 2A, the developing device 58 includes a developing unit 72 that visualizes the electrostatic latent image on the photoreceptor 36 with toner, and a main toner supply that supplies the toner T to the developing unit 72. The unit 74 is integrated in the lateral direction. The developing device 58 uses a two-component developing system in which the toner T is triboelectrically developed by stirring and mixing with a carrier.

  The developing unit 72 has a housing 76 as a main body. The housing 76 is provided on the lower side of the photoconductor 36 and has an opening 78 that opens toward the photoconductor 36. A developer accommodating chamber 80 is formed in the housing 76. The developer storage chamber 80 stores therein a developer G composed of toner T and carrier. Note that the carrier is accommodated only in the developer accommodating chamber 80.

  Further, a developing roll 82 is disposed in the housing 76 so as to be partially exposed from the opening 78. The developing roll 82 includes a non-magnetic cylindrical developing sleeve (not shown) that is rotatably provided in the direction of the arrow, and a magnet roll that is fixed so as not to rotate inside the developing sleeve and is provided with a plurality of magnetic poles alternately. (Not shown). A gear (not shown) is fixed to the end portion of the developing sleeve, and the rotational force from the motor is transmitted to the gear so that the developing sleeve rotates via the gear.

  Here, the developing roll 82 adsorbs the carrier contained in the developer G by magnetic force, forms a magnetic brush of the developer G on the surface, and develops the toner T adsorbed on the carrier to the photosensitive member 36. Transport to (developer supply position). Then, the electrostatic latent image formed on the photosensitive member 36 by the exposure light L is visualized by a magnetic brush of the developer G made of carrier and toner formed on the surface of the developing roll 82. It has become.

  A cylindrical layer thickness regulating member 84 is disposed on the upstream side of the developing area in the developing roll 82 and spaced apart from the developing roll 82 by a predetermined distance and along the axial direction of the developing roll 82. The layer thickness regulating member 84 is made of a non-magnetic material such as aluminum and regulates the layer thickness of the developer G supplied onto the developing roll 82.

  As shown in FIGS. 2A, 3, and 4, a first auger 86 and a second auger 88 are disposed below the developing roll 82 along the axial direction of the developing roll 82. The first auger 86 and the second auger 88 are provided with rotating shafts 86A and 88A, respectively, and are rotatably supported on the peripheral wall of the housing 76, respectively. Spiral blades 86B and 88B are spirally formed on the rotation shafts 86A and 88A, respectively, at a predetermined pitch.

  Here, gears (not shown) are fixed to the end portions of the rotation shafts 86A and 88A, respectively, and a rotational force from a motor (not shown) is transmitted to the gears, and the first auger 86 and the second auger 88 are transmitted via the gears. Each rotate. By rotating the spiral blades 86B and 88B by this rotation, the developer G accommodated in the developer accommodating chamber 80 is conveyed in the arrow direction (see FIG. 4) while being stirred.

  A first partition wall 90 is erected between the first auger 86 and the second auger 88. The developer storage chamber 80 is divided into two by a first partition wall 90 into a first stirring path 92 in which a first auger 86 is disposed and a second stirring path 94 in which a second auger 88 is disposed. Yes.

  Further, communication ports 96 and 98 are formed at both longitudinal ends of the first partition wall 90, and the first stirring channel 92 and the second stirring channel 94 are communicated with each other by the communication ports 96 and 98. ing. Here, the developer G in the developer storage chamber 80 is conveyed while being stirred in the first stirring path 92 and the second stirring path 94 by the rotation of the first auger 86 and the second auger 88, respectively. It circulates between the stirring path 92 and the second stirring path 94.

  A main toner supply unit 74 adjacent to the developing unit 72 is provided with a toner storage chamber 102 in which supply toner T is stored. A first agitator 104 and a second agitator 106 are rotatably provided in the toner storage chamber 102 along the axial direction of the developing roll 82.

  The first agitator 104 includes a first rotating shaft 104A and a first transport film 104B made of mylar, and is rotatably supported on the peripheral wall of the main toner supply unit 74. The second agitator 106 includes a first rotating shaft 106 </ b> A and a second transport film 106 </ b> B made of Mylar, and is rotatably supported on the peripheral wall of the main toner supply unit 74. The first transport film 104B and the second transport film 106B are cut obliquely in the toner transport direction.

  A gear (not shown) is fixed to the ends of the first rotating shaft 104A and the second rotating shaft 106A. Here, when a rotational force from a motor (not shown) is transmitted to the gear and the first transport film 104B and the second transport film 106B rotate, the toner T in the toner storage chamber 102 is transported in the arrow direction while being stirred. It has become.

  Next, the toner conveyance path 114 will be described.

  As shown in FIGS. 2A, 3, and 4, a second partition wall 108, a curved wall 110, and a third partition wall 112 are provided between the toner storage chamber 102 and the developer storage chamber 80. Is provided. From the lower part of the second partition wall 108, the curved wall 110 extends toward the toner storage chamber 102, and the third partition wall 112 extends toward the developer storage chamber 80, whereby a tunnel-shaped toner conveyance path is formed at the bottom of the housing 76. 114 is formed.

  The toner conveyance path 114 is provided in parallel with the toner feeding direction of the first agitator 104. In the toner conveyance path 114, a conveyance auger 116 that stirs and conveys toner along the longitudinal direction is rotatably provided.

  Here, a toner inflow port 118 is formed in the vicinity of one end of the curved wall 110 in the longitudinal direction so as to communicate the toner storage chamber 102 and the toner conveyance path 114. As a result, the toner T stored in the toner storage chamber 102 is transported in the axial direction in the toner storage chamber 102 while being stirred by the first agitator 104, and sent to the toner transport path 114 from the toner inlet 118. It has become.

  On the other hand, a toner supply port 120 is formed in the vicinity of the other end portion in the longitudinal direction of the third partition wall 112 so as to communicate the toner conveyance path 114 and the developer storage chamber 80. Thus, the toner T in the toner conveyance path 114 is conveyed while being agitated by the conveyance auger 116 and is sent from the toner supply port 120 to the developer storage chamber 80.

  As shown in FIG. 2B, the toner conveyance path 114 has a bottom surface inclined at an angle θ1 from the bottom surface of the developing unit 72, and is inclined at a constant gradient from the toner inlet 118 to the toner supply port 120. Is formed. Accordingly, the height position A (lower end portion) of the toner supply port 120 is higher than the lowermost portion (bottom surface) B of the toner conveyance path 114 on the toner inflow port 118 side.

  Further, the transport auger 116 includes a rotating shaft 116A and a spiral blade 116B formed in a spiral shape on the rotating shaft 116A. The spiral blade 116B is formed so that d1> d2, where d1 is a pitch (arrangement interval) on the toner inlet 118 side and d2 is a pitch on the toner supply port 120 side. The conveyance speed is slow. In the transport auger 116, the spiral blade 116B at the end on the toner supply port 120 side is partially directed in the reverse direction. This is because the toner T stays at the downstream end of the toner transport path 114. Is to prevent.

  As shown in FIG. 2A, the toner supply port 120 is formed so that the lower end portion is positioned below the surface position of the developer G stored in the developer storage chamber 80. As a result, at least a part of the toner supply port 120 is buried in the developer G accommodated in the developer accommodating chamber 80, and the toner T fed into the developer accommodating chamber 80 from the toner conveyance path 114. However, it gets into the developer G and is easily mixed with the developer G.

  Next, the operation of the first embodiment of the present invention will be described.

  First, image formation of the printer 10 will be described. As shown in FIG. 1, when image formation is started by pressing a start button (not shown) in the printer 10, the control unit 54 controls the operation of each part of the printer 10, and the paper feed cassette 14 is picked up by the pickup roll 16. The recording paper P is sent out from. The sent recording paper P is sent to the paper transport path 22 via the transport roll 18 and the registration roll 20 and transported to the transport device 24.

  Subsequently, in each image forming unit 12, the photosensitive member 36 is charged by the charging roll 60, and exposure light L is irradiated from the exposure device 26 to the photosensitive member 36 based on various data for forming an image. Thereby, an electrostatic latent image is formed on the photoconductor 36. Then, this electrostatic latent image is made visible by the toner T on the developing roll 82 and becomes a toner image.

  The toner image on the photosensitive member 36 is sequentially transferred onto the recording paper P conveyed by the conveying belt 42 by the transfer electric field of the transfer roll 46, and the toner of each color is superimposed. The recording paper P onto which the toner image has been transferred is fixed by the fixing device 48 by the action of heat and pressure. The recording paper P that has been fixed is discharged to the discharge tray 52 by the discharge roll 50. In this way, image formation is performed.

  Next, the conveyance state of the toner T in the toner conveyance path 114 will be described.

  As shown in FIG. 5A, in the toner conveyance path 114, the toner T flows from the toner inlet 118 by the rotation of the first agitator 104 (see FIG. 4). Here, since the toner conveyance path 114 is inclined, the inflowing toner T starts to be stored from the lower part (corner part) of the inner wall 114A at the end of the toner conveyance path 114. When the toner T continuously flows from the toner inlet 118, first, the toner T near the toner inlet 118 is densely filled in the toner conveyance path 114.

  Subsequently, as shown in FIGS. 5B and 5C, the toner T near the toner inlet 118 is conveyed toward the downstream side (toner supply port 120 side) by the rotation of the conveyance auger 116. The Here, since the toner conveyance path 114 is inclined as described above, the toner T is filled so as to be densest on the upstream side in the conveyance direction. For this reason, the toner T conveyed toward the downstream side is always dense on the upstream side, and it becomes difficult to form a portion where the density of toner is sparse during the conveyance, and continuously to the toner supply port 120 at a predetermined conveyance rate. Will be transported. The transport rate is defined by the transport amount (supply amount) of the toner T per unit time and is in units (mg / sec).

  Here, as a comparative example, in the case where the toner conveyance path is horizontally arranged, the toner distribution changes in the toner conveyance path due to aggregation of the toner T in the middle of conveyance due to disturbances such as environmental temperature and vibration. However, it becomes difficult to maintain a predetermined conveyance rate. Further, in the case where the toner conveyance path is inclined so as to be lowered from the upstream side to the downstream side in the conveyance direction, the toner T falls at a stroke due to the weight of the toner T, etc. It becomes difficult to maintain the rate.

  On the other hand, in the present embodiment, as described above, since the toner transport path 114 is directed upward from the upstream side to the downstream side, the transported toner T is always dense on the upstream side. Accordingly, it becomes difficult to form a portion where the toner density is sparse during the conveyance, and the toner can be continuously conveyed to the toner supply port 120 at a predetermined conveyance rate.

  The toner T that has reached the toner supply port 120 is sequentially supplied from the toner supply port 120 to the developer storage chamber 80 (see FIG. 2A). Here, since the pitch of the spiral blades 116B near the toner supply port 120 is narrower than the pitch of the upstream spiral blades 116B, the transport speed of the toner T transported from the upstream side decreases near the toner supply port 120. To do. Thus, the toner T temporarily stays in the vicinity of the toner supply port 120, and the toner supply from the toner supply port 120 is continuously performed.

  Since the toner conveyance path 114 is disposed in parallel with the developer G feeding direction of the first auger 86 and the second auger 88, the toner storage chamber 102 approaches the developing unit 72, and the length of the toner conveyance path 114 is increased. Is getting shorter. Also in this respect, the density of the toner T is suppressed from becoming sparse in the toner conveyance path 114.

  Here, FIG. 6 shows the relationship between the accumulated time from the start of rotation of the transport auger 116 in the developing device 58 and the transport rate in the toner transport path 114. In FIG. 6, the data of the developing device 58 of the present embodiment is represented by a black circle plot, and as a comparative example, the data of the toner transport path 114 arranged horizontally is a triangular plot, and the toner transport path 114 is low toward the toner supply port 120. The tilted data is represented by a square plot. In FIG. 6, the pitch of the spiral blades 116B on the toner supply port 120 side of the present embodiment is set to 15 mm.

  As shown in FIG. 6, when the conveyance rates up to the accumulated time of 1200 seconds are compared, the horizontal arrangement, which is a comparative example, varies from 160 to 200 [mg / sec], and the lower arrangement is 200 to 250 [mg / sec]. However, in the developing device 58 of the present embodiment, it was 200 to 220 [mg / sec], and it was confirmed that the fluctuation range of the conveyance rate was small.

  On the other hand, FIG. 7 shows the relationship between the remaining amount of toner in the toner storage chamber 102 and the conveyance rate in the toner conveyance path 114. Note that the remaining amount of toner in the toner storage chamber 102 at the start of measurement is set to 100 g in advance. Also, FIG. 7 shows data in the developing device 58 of the present embodiment, and the data of the spiral blade 116B set on the toner supply port 120 side at a pitch of 15 mm is plotted with white circles, and the toner on the spiral blade 116B. Data obtained by narrowing the pitch on the supply port 120 side to 5 mm is represented by a triangular plot.

  As shown in FIG. 7, as the remaining amount of toner decreases, the conveyance rate tends to decrease gradually when the pitch of the spiral blades 116B is 15 mm. However, when the pitch is 5 mm, the conveyance rate increases. Although the absolute value was low, a tendency for the conveyance rate to stabilize was confirmed.

  Next, a second embodiment of the developing device and the image forming apparatus of the present invention will be described with reference to the drawings. Note that components that are basically the same as those in the first embodiment described above are given the same reference numerals as those in the first embodiment, and descriptions thereof are omitted.

  FIG. 8A shows an image forming unit 130 that can be attached to the printer 10 (see FIG. 1). In the image forming unit 130, a photosensitive member 36 is rotatably provided in a housing 132 constituting a main body. Around the photoreceptor 36, a charging roll 60, an exposure unit 134 that irradiates the charged photoreceptor 36 with exposure light, a developing roll 82, and a cleaning device 62 are disposed.

  Around the developing roll 82, a layer thickness regulating member 84 is provided on the upper side, and a toner supply roll 136 is provided on the lower side. The toner supply roll 136 has an axial direction parallel to the axial direction of the developing roll 82, and supplies the toner T to the developing roll 82. A developer storage chamber 138 is provided at a position adjacent to the toner supply roll 136.

  In the developer storage chamber 138, stirring augers 140 and 142 are rotatably provided in parallel. Further, a developer G composed of toner and a carrier is accommodated from the lower part of the developing roll 82 to the developer accommodating chamber 138. A partition wall 144 is provided between the stirring auger 140 and the toner supply roll 136, and a supply port 146 through which the toner T is supplied is formed below the partition wall 144. As a result, the toner T is supplied from the developer storage chamber 138 to the toner supply roll 136, and the toner T is further supplied to the development roll 82. The developing section 160 is formed by the developing roll 82, the layer thickness regulating member 84, the toner supply roll 136, the stirring augers 140 and 142, and a part of the housing 132 that contains them.

  A partition wall 148 is formed between the stirring auger 140 and the stirring auger 142. Communication ports 150 and 152 are formed at both ends in the longitudinal direction of the partition wall 148 (the front side and the back side in the drawing). Thus, when the stirring auger 140 and the stirring auger 142 rotate, the developer G is stirred in the developer storage chamber 138. Further, a toner conveyance path 154 that conveys the toner T to the developer storage chamber 138 is provided above the stirring auger 142.

  As shown in FIGS. 8A and 8B, the toner conveyance path 154 is disposed in parallel with the developer G feeding direction of the stirring augers 140 and 142, and the toner conveyance path 154 A toner supply port 156 that can supply the toner T to the developer storage chamber 138 is formed at the bottom of one end. A toner inlet 158 that allows the toner T to flow into the toner conveyance path 154 is formed at the upper part of the other end of the toner conveyance path 154.

  The toner conveyance path 154 is formed so that the bottom surface is inclined at an angle θ2 from the bottom surface of the image forming unit 130 and is inclined at a constant gradient from the toner inflow port 158 to the toner supply port 156. Thus, the height position C (upper end portion) of the toner supply port 156 is higher than the lowermost portion (bottom surface) D of the toner conveyance path 154 on the toner inflow port 158 side.

  A transport auger 162 that stirs and transports the toner T along the longitudinal direction is rotatably provided in the toner transport path 154. The conveyance auger 162 includes a rotation shaft 162A and a spiral blade 162B formed in a spiral shape on the rotation shaft 162A. The spiral blade 162B is formed such that the pitch on the toner supply port 156 side is smaller than the pitch on the toner inflow port 158 side, and the transport speed of the toner T becomes slow on the toner supply port 156 side. Yes.

  On the upper wall of the toner conveyance path 154 around the toner inflow port 158, a receiving portion 164 is provided that protrudes in a plate shape in a substantially horizontal direction and has an end portion standing in a substantially L shape. The receiving portion 164 is mounted with a mounting portion 168 that protrudes in a plate shape in a substantially horizontal direction on the bottom side of the toner cartridge 166 containing the toner T. The toner cartridge 166 can be attached to and detached from the image forming unit 130.

  Further, the toner cartridge 166 is provided with an agitator 170 for stirring so as to be rotatable. Further, a toner outlet 172 wider than the toner inlet 158 is formed at the bottom of the toner cartridge 166. The toner outlet 172 is covered with a lid (not shown) before the attachment portion 168 of the toner cartridge 166 is attached to the receiving portion 164 so that the toner T does not flow out.

  Here, the developing unit 160 includes the developing unit 160, the toner conveyance path 154, and the toner cartridge 166. When the toner cartridge 166 is replaced in the developing device 133 (image forming unit 130), a lid (not shown) is inserted from the front side to the back side of the sheet, and the toner outlet 172 is closed. Then, the toner cartridge 166 is pulled out toward the front side of the paper, and a new toner cartridge 166 is inserted toward the back side of the paper.

  The inserted new toner cartridge 166 is fixed by being urged by an urging means such as a leaf spring (not shown) from the front side of the paper surface with the mounting portion 168 engaged with the receiving portion 164. The toner T in the new toner cartridge 166 flows down the toner outlet 172 and the toner inlet 158 by pulling out a cover (not shown) that closes the toner outlet 172 of the new toner cartridge 166 to the front side of the sheet. Then, the toner flows into the toner conveyance path 154.

  Next, the operation of the second embodiment of the present invention will be described.

  First, image formation will be described. When image formation is started by pressing a start button (not shown) in the printer 10 (see FIG. 1), the control unit 54 controls the operation of each part of the printer 10, and the start pickup roll 16 removes the paper from the paper cassette 14. The recording paper P is sent out. The sent recording paper P is sent to the paper transport path 22 via the transport roll 18 and the registration roll 20 and transported to the transport device 24.

  Subsequently, in each image forming unit 130, the photoreceptor 36 is charged by the charging roll 60, and exposure light is irradiated from the exposure unit 134 to the photoreceptor 36 based on various data for forming an image. Thereby, an electrostatic latent image is formed on the photoconductor 36. Then, this electrostatic latent image is made visible by the toner T on the developing roll 82 and becomes a toner image.

  The toner image on the photosensitive member 36 is sequentially transferred onto the recording paper P conveyed by the conveying belt 42 by the transfer electric field of the transfer roll 46, and the toner of each color is superimposed. The recording paper P onto which the toner image has been transferred is fixed by the fixing device 48 by the action of heat and pressure. The recording paper P that has been fixed is discharged to the discharge tray 52 by the discharge roll 50. In this way, image formation is performed.

  Next, the conveyance state of the toner T in the toner conveyance path 154 will be described.

  As shown in FIG. 9A, in the toner conveyance path 154, the toner T that has flowed out from the toner outlet 172 of the toner cartridge 166 (see FIG. 8A) flows into the toner inlet 158. Here, since the toner conveyance path 154 is inclined, the inflowing toner T starts to be stored from the lower part (corner part) of the inner wall 154A at the end of the toner conveyance path 154. When the toner T continuously flows from the toner inlet 158, first, the toner T near the toner inlet 158 is densely filled in the toner conveyance path 154.

  Subsequently, as shown in FIGS. 9B and 9C, the toner T near the toner inflow port 158 is transported toward the downstream side (toner supply port 156 side) by the rotation of the transport auger 162. The Here, since the toner conveyance path 154 is inclined as described above, the toner T is filled so as to be the most dense on the upstream side in the conveyance direction. For this reason, the toner T conveyed toward the downstream side is always dense on the upstream side, and it is difficult to form a portion where the density of the toner is sparse during the conveyance, and continuously to the toner supply port 156 at a predetermined conveyance rate. Will be transported.

  Here, as a comparative example, in the case where the toner conveyance path is horizontally arranged, the toner distribution changes in the toner conveyance path due to aggregation of the toner T in the middle of conveyance due to disturbances such as environmental temperature and vibration. However, it becomes difficult to maintain a predetermined conveyance rate. Further, in the case where the toner conveyance path is inclined so as to be lowered from the upstream side to the downstream side in the conveyance direction, the toner T falls at a stroke due to the weight of the toner T, etc. It becomes difficult to maintain the rate.

  On the other hand, in the present embodiment, as described above, since the toner transport path 114 is directed upward from the upstream side to the downstream side, the transported toner T is always dense on the upstream side. Accordingly, it becomes difficult to form a portion where the density of the toner T is sparse during the conveyance, and the toner T can be continuously conveyed to the toner supply port 156 at a predetermined conveyance rate.

  The toner T that has reached the toner supply port 156 is sequentially supplied from the toner supply port 156 to the developer storage chamber 138 (see FIG. 8A). Here, since the pitch of the spiral blade 162B near the toner supply port 156 is narrower than the pitch of the upstream spiral blade 162B, the transport speed of the toner T transported from the upstream side decreases near the toner supply port 156. To do. As a result, the toner T temporarily stays in the vicinity of the toner supply port 156, and the toner supply from the toner supply port 156 is continuously performed.

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

  As shown in FIG. 10A, the toner conveyance speed near the toner supply port may be decreased by using a conveyance auger 176 in which the diameter of the spiral blade is changed. The transport auger 176 has a rotating shaft 176A, a spiral blade 176B having a diameter R1 that is spirally formed on the rotating shaft 176A and disposed on the toner inlet side, and a spiral that is formed on the rotating shaft 176A and disposed on the toner supply port side. And a spiral blade 176C having a diameter R2 (R1> R2). Further, the pitch d2 of the spiral blade 176C is smaller than the pitch d1 of the spiral blade 176B. Accordingly, the toner conveyance speed may be further decreased on the toner supply port 120 side to increase the toner retention amount.

  Further, as shown in FIG. 10B, a toner conveyance path 182 that is partially inclined may be used. A toner conveyance path 182 is provided in the developing device 180. The toner conveyance path 182 is provided such that the region of the length L1 of the housing 184 on the toner inlet 188 side is flat, and the region of the length L2 of the housing 184 is inclined at an angle θ3 toward the toner supply port 190. Has been. A plate-like support portion 186 protrudes from the upper wall of the length L1 region of the toner conveyance path 182. One end of the conveyance auger 116 is inserted into the through hole 186A formed in the support portion 186. It becomes the composition. Note that the region to be a flat portion may be provided in the vicinity of the toner supply port 190.

1 is an overall view of an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a perspective view of the inside of the developing device according to the first embodiment of the present invention. (A) It is sectional drawing of the image forming unit which concerns on 1st Embodiment of this invention. (B) It is sectional drawing of the toner conveyance path which concerns on 1st Embodiment of this invention. 1 is a cross-sectional view of a developing device according to a first embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a toner conveyance state inside a toner conveyance path according to the first exemplary embodiment of the present invention. 6 is a graph showing the relationship between the accumulated time from the start of rotation of the toner conveying member and the conveying rate in the developing device according to the first embodiment of the present invention. 6 is a graph showing a relationship between a remaining toner amount and a conveyance rate in the developing device according to the first embodiment of the present invention. (A) It is sectional drawing of the image forming unit which concerns on 2nd Embodiment of this invention. (B) It is sectional drawing of the toner conveyance path which concerns on 2nd Embodiment of this invention. FIG. 6 is a schematic diagram illustrating a toner conveyance state inside a toner conveyance path according to a second embodiment of the present invention. (A) It is a schematic diagram which shows the other Example of the toner conveyance member of this invention. (B) It is sectional drawing which shows the other Example of the toner conveyance path of this invention.

Explanation of symbols

10 Printer (image forming device)
26 Exposure device (latent image forming means)
36 photoconductor (photoconductor)
58 Developing device (Developing device)
72 Development Unit (Development Unit)
82 Developing Roll (Developer Holding Member)
86 1st auger (developer stirring member)
88 2nd auger (developer stirring member)
102 Toner storage chamber (developer storage section)
114 Toner transport path (Developer transport path)
116 transport auger (developer transport member)
118 Toner inlet (developer inlet)
120 Toner supply port (Developer supply port)
133 Developing device (Developing device)
140 Stirring auger (developer stirring member)
142 Stirring auger (Developer stirring member)
154 Toner transport path (developer transport path)
156 Toner supply port (developer supply port)
158 Toner inlet (developer inlet)
160 Development Section (Development Section)
162 Transport auger (developer transport member)
166 Toner cartridge (developer container)
T Toner (Developer)

Claims (5)

A developer container containing a developer;
A developing unit having a developer stirring member that stirs the developer sent from the developer storage unit, and a developer holding member that holds the developer stirred by the developer stirring member and supplies the developer to the photosensitive member; ,
A developer inflow port from which the developer is introduced from the developer accommodating portion and a developer supply port to which the developer introduced from the developer inflow port is supplied to the developing portion are formed, and the developer A developer transport path provided with a developer transport member for transporting the developer from the inflow port to the developer supply port;
Have
The developer conveying path is arranged so as to be parallel to the developer feeding direction of the developer stirring member,
The position of the lower end of the developer supply port is higher than the lowest part on the developer inlet side of the developer transport path;
The developer transport member includes a first transport unit that transports the developer in a forward direction from the developer inflow port to the developer supply port toward the developer supply port, and the order toward the developer supply port. A second transport unit that transports the developer in a direction opposite to the direction,
The first transport unit is configured such that the transport speed of the developer on the downstream side in the forward direction is slower than the upstream side than the intermediate position between the developer inlet and the developer supply port.
The second transport unit has a configuration in which a developer transport speed in a facing region facing the developer supply port is slower than a developer transport speed of the first transport unit upstream of the intermediate position. Development device. The first transport unit and the second transport unit have spiral blades,
The pitch of the spiral blades of the first transport unit and the second transport unit in the opposed region is narrower than the pitch of the spiral blades of the first transport unit on the upstream side of the intermediate position. The developing device described.   The developing device according to claim 1, wherein the developer conveyance path is inclined at a constant gradient from the developer inflow port to the developer supply port.   The developing device according to claim 1, wherein the developer accommodating portion is detachable from the developer conveyance path. Latent image forming means for forming a latent image of the image on the photoreceptor;
A developing device according to any one of claims 1 to 4,
Have
An image forming apparatus in which the developer holding member supplies the developer to the latent image and develops the latent image.

Images