WO2015178506A1 - 画像形成装置 - Google Patents
画像形成装置 Download PDFInfo
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- WO2015178506A1 WO2015178506A1 PCT/JP2015/065489 JP2015065489W WO2015178506A1 WO 2015178506 A1 WO2015178506 A1 WO 2015178506A1 JP 2015065489 W JP2015065489 W JP 2015065489W WO 2015178506 A1 WO2015178506 A1 WO 2015178506A1
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- developer
- humidity
- driving
- developing
- screw
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
- G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
- G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
- G03G15/0822—Arrangements for preparing, mixing, supplying or dispensing developer
- G03G15/0865—Arrangements for supplying new developer
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
- G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
- G03G15/0822—Arrangements for preparing, mixing, supplying or dispensing developer
- G03G15/0887—Arrangements for conveying and conditioning developer in the developing unit, e.g. agitating, removing impurities or humidity
- G03G15/0891—Arrangements for conveying and conditioning developer in the developing unit, e.g. agitating, removing impurities or humidity for conveying or circulating developer, e.g. augers
- G03G15/0893—Arrangements for conveying and conditioning developer in the developing unit, e.g. agitating, removing impurities or humidity for conveying or circulating developer, e.g. augers in a closed loop within the sump of the developing device
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
- G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
- G03G15/0822—Arrangements for preparing, mixing, supplying or dispensing developer
- G03G15/0865—Arrangements for supplying new developer
- G03G15/0867—Arrangements for supplying new developer cylindrical developer cartridges, e.g. toner bottles for the developer replenishing opening
- G03G15/087—Developer cartridges having a longitudinal rotational axis, around which at least one part is rotated when mounting or using the cartridge
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
- G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
- G03G15/0822—Arrangements for preparing, mixing, supplying or dispensing developer
- G03G15/0887—Arrangements for conveying and conditioning developer in the developing unit, e.g. agitating, removing impurities or humidity
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/06—Developing structures, details
- G03G2215/066—Toner cartridge or other attachable and detachable container for supplying developer material to replace the used material
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/08—Details of powder developing device not concerning the development directly
- G03G2215/0802—Arrangements for agitating or circulating developer material
- G03G2215/0816—Agitator type
- G03G2215/0827—Augers
- G03G2215/0833—Augers with varying pitch on one shaft
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/08—Details of powder developing device not concerning the development directly
- G03G2215/0802—Arrangements for agitating or circulating developer material
- G03G2215/0836—Way of functioning of agitator means
- G03G2215/0838—Circulation of developer in a closed loop within the sump of the developing device
Definitions
- the present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine having a plurality of these functions.
- an electrostatic latent image formed on a photosensitive drum as an image carrier is developed as a toner image by a developer containing toner and a carrier.
- the toner and the carrier are frictionally charged by rotating the conveying screw and conveying the developer while stirring in the circulation path in the developing container.
- the carrier that is not consumed by the image formation continues to circulate while receiving friction in the developing container, so that the charging performance of the carrier gradually decreases.
- a developing device configured such that a circumferential or outward radial force acting on the developer by rotation of a conveying screw in a region facing the developer discharge port is smaller than in other regions. It has been proposed (Japanese Patent Laid-Open No. 2000-112238). Specifically, a configuration in which the blades of the conveying screw in a region facing the developer discharge port are made smaller or a blade is omitted is shown.
- the present invention has been invented to appropriately discharge the developer with a configuration in which the developer conveying capacity of the conveying screw in the region facing the discharge port is low.
- an image carrier a developing device for developing a latent image formed on the image carrier, a developer container containing a developer, and a developer in the developer container
- a developing device comprising: a conveying screw that conveys the developer; and a discharge port that is provided on a side surface of the developing container so as to face the conveying screw and discharges excess developer in the developing container;
- a replenishing device for replenishing the developer to the container, a driving device for rotationally driving the conveying screw, an acquisition unit for acquiring information on the charge amount of the developer, and a control unit for controlling the driving device
- the conveying screw is formed so that an outer diameter of a first region including a portion facing the discharge port is smaller than an outer diameter of a second region adjacent to the first region, and the control unit Based on the information of the acquisition unit, the case where the charge amount of the developer corresponds to the second charge amount lower than the first charge amount than the case where the charge amount of the developer corresponds to the first charge amount,
- the driving speed of the conveying screw is controlled to be high in a state where the charge amount at which the developer fluidity is high is low, the developer fluidity is high and the developer is in the vicinity of the discharge port. Even if it is difficult to stay in the developer, the developer can be discharged properly by raising the surface of the developer.
- FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention.
- FIG. 2 is a schematic cross-sectional view of the developing device according to the first embodiment.
- FIG. 3 is a longitudinal sectional view schematically showing the same configuration.
- FIG. 4 is a schematic diagram illustrating a conveying screw in the vicinity of a discharge port of the developing device according to the first embodiment.
- FIG. 5 is a schematic diagram showing another three examples of the conveying screw in the vicinity of the discharge port of the developing device according to the first embodiment.
- FIG. 6 is a view showing the discharge characteristic of the developer from the discharge port.
- FIG. 7 is a schematic view showing the developer surface of the developer near the discharge port.
- FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention.
- FIG. 2 is a schematic cross-sectional view of the developing device according to the first embodiment.
- FIG. 3 is a longitudinal sectional view schematically showing the same configuration.
- FIG. 8A is a schematic diagram showing the developer surface near the discharge port when the developer has low fluidity, and FIG. 8B when the developer has high fluidity.
- FIG. 9 is a control block diagram of the image forming apparatus according to the first embodiment.
- FIG. 10 is a flowchart of control when starting up the developing device according to the first embodiment.
- FIG. 11 is a diagram showing a change in the developer amount in the developing container with respect to the developer humidity of each image DUTY in the comparative example of the present invention.
- FIG. 12 is a diagram illustrating a change in the developer amount in the developing container with respect to the developer humidity of each image DUTY in the first embodiment of the present invention.
- FIG. 13 is a control block diagram of the image forming apparatus according to the second embodiment of the present invention.
- FIG. 14 is a flowchart of control when starting up the developing device according to the second embodiment.
- FIG. 15 is a diagram illustrating a change in the amount of developer in the developing container with respect to the developer humidity of each image DUTY in Example 2 of the present invention.
- FIG. 16 is a control block diagram of the image forming apparatus according to the third embodiment of the present invention.
- FIG. 17 is a flowchart of control when starting up the developing device according to the third embodiment.
- FIG. 18 is a diagram showing a change in the developer amount in the developing container with respect to the developer humidity of each image DUTY in Example 3 of the present invention.
- FIG. 19 is a flowchart of control at the start-up of the developing device according to the fourth embodiment of the present invention.
- FIG. 15 is a diagram illustrating a change in the amount of developer in the developing container with respect to the developer humidity of each image DUTY in Example 2 of the present invention.
- FIG. 16 is a control block diagram of the image forming apparatus according to the
- FIG. 21 is a schematic cross-sectional view of a developing device of a first example of another embodiment of the present invention.
- FIG. 22 is a schematic cross-sectional view of a second example of the developing device according to another embodiment of the present invention.
- FIGS. A first embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of the image forming apparatus of the present embodiment will be described with reference to FIG. [Image forming apparatus]
- the image forming apparatus 100 of the present embodiment is a full-color image forming apparatus that employs an electrophotographic system, and includes four image forming units P (Pa, Pb, Pc, Pd).
- Each of the image forming units Pa to Pd includes a drum-shaped electrophotographic photosensitive member that rotates in an arrow direction (counterclockwise) as an image carrier, that is, a photosensitive drum 1 (1a, 1b, 1c, 1d).
- a charger 2 (2a, 2b, 2c, 2d)
- a developing device 4 (4a, 4b, 4c, 4d)
- a primary transfer roller 6 (6a, 6b, 6c, 6d
- a cleaning device 19 (19a, 19b, 19c, 19d) and the like.
- a laser beam scanner 3 (3a, 3b, 3c, 3d) as an exposure unit is disposed above the photosensitive drum 1 in FIG.
- the photosensitive drum 1 is uniformly charged by a charger 2 as a charging unit.
- the uniformly charged photosensitive drum 1 is subjected to scanning exposure by the laser beam scanner 3 using laser light modulated by an image signal.
- the laser beam scanner 3 incorporates a semiconductor laser, and this semiconductor laser is controlled in response to an original image information signal output from an original reading apparatus having a photoelectric conversion element such as a CCD, and emits laser light.
- the surface potential of the photosensitive drum 1 charged by the charger 2 changes in the image portion, and an electrostatic latent image is formed on the photosensitive drum 1.
- This electrostatic latent image is reversely developed with toner by a developing device 4 as a developing means to form a visible image, that is, a toner image.
- the developing device 4 uses a two-component contact developing system that uses a developer in which toner and a carrier are mixed as a developer.
- an intermediate transfer belt 5 constituted by an endless belt as an intermediate transfer member is disposed below each image forming portion Pa, Pb, Pc, Pd.
- the intermediate transfer belt 5 is suspended by rollers 61, 62, 63 and is movable in the direction of the arrow.
- the toner image on the photosensitive drum 1 is once transferred to the intermediate transfer belt 5 by a primary transfer roller 6 as a primary transfer unit.
- toner images of four colors of yellow, magenta, cyan, and black are superimposed on the intermediate transfer belt 5 to form a full color image. Further, the toner remaining without being transferred onto the photosensitive drum 1 is collected by the cleaning device 19.
- the full-color image on the intermediate transfer belt 5 is taken out from the cassette 12 and transferred to a recording material (sheet material) S such as paper or sheet that has advanced via the feeding roller 13 and the guide 11 as a secondary transfer means. Transfer is performed by the action of the secondary transfer roller 10. The toner remaining on the surface of the intermediate transfer belt 5 without being transferred is collected by the intermediate transfer belt cleaning device 18.
- the recording material S to which the toner image has been transferred is sent to a fixing device 16 as a fixing unit, and the toner image is fixed to the recording material S by being heated and pressurized.
- the recording material S on which the toner image is fixed is discharged to the discharge tray 17.
- the photosensitive drum 1 that is a drum-shaped organic photosensitive member that is normally used is used as the image carrier.
- an inorganic photosensitive member such as an amorphous silicon photosensitive member can also be used. It is also possible to use a belt-like photoreceptor.
- the charging method, transfer method, cleaning method, and fixing method are not limited to the above methods.
- the developing device 4 includes a developing container 22 in which a two-component developer containing toner and a carrier as a developer is accommodated.
- the developing container 22 includes a developing sleeve 28 as a developer carrying member and a regulating blade 29 that regulates the ears of the developer carried on the developing sleeve 28.
- the interior of the developing container 22 is divided into a developing chamber 23 and an agitating chamber 24 by a partition wall 27 having a substantially central portion extending in a direction perpendicular to the paper surface, and the developer is accommodated in the developing chamber 23 and the agitating chamber 24. Has been.
- first and second conveying screws 25 and 26 are arranged as developer conveying members, respectively.
- the first conveying screw 25 is disposed substantially parallel to the bottom of the developing chamber 23 along the axial direction of the developing sleeve 28. Then, the developer rotates in the direction indicated by the arrow (clockwise direction) to supply the developer in the developing chamber 23 to the developing sleeve, and the developer is conveyed in one direction along the axial direction.
- the second conveying screw 26 is disposed substantially in parallel with the first conveying screw 25 at the bottom in the stirring chamber 24. Then, the developer after being rotated and rotated in the opposite direction (counterclockwise) to the first conveying screw 25 is collected, and the developer in the stirring chamber 24 is opposite to the first conveying screw 25. Transport in the direction. As described above, the developer is transported by the rotation of the first and second transport screws 25, 26, so that the developer passes through the openings (that is, communication portions) 11, 12 at both ends of the partition wall 27, Cycled between.
- the developing sleeve 28 is rotationally driven by a first driving motor M1, and the first and second conveying screws 25 and 26 are rotationally driven by a second driving motor M2 as a driving means.
- both of these motors are DC motors, and the steady state driving rotational speed during image formation is the first driving motor M1: 300 [rpm] (the second driving motor M2 will be described later).
- the first drive motor M1 is directly connected to the developing sleeve 28, and the second drive motor M2 is directly connected to the first conveying screw 25. Furthermore, the first conveying screw 25 and the second conveying screw 26 are driven and transmitted by gears at a ratio of 1: 1.07.
- the developing sleeve 28 can be rotated so that the developing sleeve 28 is partially exposed in the direction of the photosensitive drum 1. It is arranged.
- the rotation speed of the developing sleeve 28 is set to 300 rpm and the diameter is set to 20 mm
- the photosensitive drum 1 is set to a rotation speed of 120 rpm and the diameter is set to 30 mm.
- the closest region between the developing sleeve 28 and the photosensitive drum 1 is set so that development can be performed in contact with the photosensitive drum 1. ing.
- the developing sleeve 28 is made of a non-magnetic material such as aluminum or stainless steel, and a magnet roller 28m as a magnetic field means is installed in a non-rotating state therein.
- a developing sleeve 28 rotates in the direction of the arrow shown in the figure (counterclockwise) during development, and carries a two-component developer whose layer thickness is regulated by the cutting of the magnetic brush by the regulating blade 29, and this is photosensitive.
- the toner is conveyed to a developing area facing the drum 1. Then, a developer is supplied to the electrostatic latent image formed on the photosensitive drum 1 to develop the electrostatic latent image with toner.
- the regulation blade 29, which is the ear cutting member, is composed of a nonmagnetic member 29a formed of plate-like aluminum or the like extending along the longitudinal axis of the developing sleeve 28, and a magnetic member 29b such as an iron material. Yes. Further, by adjusting the gap between the regulating blade 29 and the surface of the developing sleeve 28, the amount of developer conveyed to the developing region is adjusted. In the present embodiment, the amount of developer coat per unit area on the developing sleeve 28 is regulated to 30 mg / cm 2 by the regulating blade 29.
- the gap between the regulating blade 29 and the developing sleeve 28 is set to 200 to 1000 ⁇ m, preferably 300 to 700 ⁇ m. In this embodiment, it is set to 400 ⁇ m. [Developer]
- the toner includes colored resin particles containing a binder resin, a colorant, and other additives as necessary, and colored particles to which an external additive such as colloidal silica fine powder is externally added.
- the toner is a negatively chargeable polyester resin, and the volume average particle size is preferably 4 ⁇ m or more and 10 ⁇ m or less. More preferably, it is 8 ⁇ m or less.
- the carrier for example, surface-oxidized or non-oxidized iron, nickel, cobalt, manganese, chromium, rare earth and other metals and their alloys, or oxide ferrite can be preferably used.
- the method for producing the particles is not particularly limited.
- the carrier has a weight average particle diameter of 20 to 60 ⁇ m, preferably 30 to 50 ⁇ m, and a resistivity of 10 7 ⁇ cm or more, preferably 10 8 ⁇ cm or more. In this embodiment, 10 8 ⁇ cm is used.
- a hopper 31 for storing a two-component developer for replenishment in which toner and a carrier are mixed is disposed on the upper part of the developing device 4.
- the hopper 31 constituting the replenishing means includes a replenishing screw 32 as a screw-like conveying member at a lower portion, and one end of the replenishing screw 32 extends to the position of the developer replenishing port 30 provided at the front end portion of the developing device 4. Yes.
- the toner consumed by the image formation passes through the developer supply port 30 from the hopper 31 and is supplied to the developing container 22 by the rotational force of the supply screw 32 and the gravity of the developer. In this way, the replenishment developer is supplied from the hopper 31 to the developing device 4.
- the replenishment amount of the replenishment developer is roughly determined by the number of rotations of the replenishment screw 32 that is a conveying member. This number of rotations is determined by a toner replenishment amount control unit (not shown).
- a toner replenishment amount control method there are a method of optically or magnetically detecting the toner density of a two-component developer, a method of developing a reference latent image on the photosensitive drum 1 and detecting the density of the toner image, and the like. Since it is known, any method can be selected as appropriate. [Developer discharge]
- the developer container 22 has a discharge port 40 for discharging the developer at a predetermined height position.
- a discharge port 40 is provided outside the developing sleeve installation area on the downstream side in the developer transport direction of the developing chamber 23, and the developer is discharged from the discharge port 40.
- the developer in the developing device 4 is increased by the developer replenishment process as described above, the developer is discharged so as to overflow from the discharge port 40 according to the increase amount.
- the position of the discharge port 40 in the developer transport direction is upstream of the position of the developer supply port 30 in the developer transport direction. This is to prevent the replenished new developer from being discharged immediately.
- the height position of the discharge port 40 is set so that the amount of developer in the developer container 22 becomes an appropriate amount in consideration of the developer discharge characteristic described later.
- the first conveying screw 25 of the developing chamber 23 in which the discharge port 40 is formed is part of a blade 25b formed in a spiral around the rotation shaft 25a. It is formed by cutting away. That is, only the rotating shaft 25a exists and the blade
- the blade 25b exists in the second region ⁇ adjacent to the first region ⁇ .
- the developer conveying capability in the first region ⁇ of the first conveying screw 25 is made lower than the developer conveying capability in the second region ⁇ .
- the rotation shaft 25a exists in the first region ⁇ , and the blades 25b exist in the second region ⁇ . Therefore, the outer diameter (rotation) of the first region ⁇ of the first conveying screw 25 is reduced.
- the outer diameter of the shaft 25a is smaller than the outer diameter of the second region (the diameter of the circumscribed circle of the blade 25b).
- the developer since the developer is hardly transported in the first region ⁇ by this configuration, the developer stays in the vicinity of the discharge port 40, and the developer level is raised to discharge the developer. It is discharged from the outlet 40.
- the length of the 1st field alpha part which notched blade 25b of the 1st conveyance screw 25 was 14 mm
- the length of the screw axis direction of outlet 40 was 10 mm.
- the center of the first region ⁇ in the screw axis direction coincides with the center of the discharge port 40 in the screw axis direction.
- the position of the first region ⁇ portion and the outlet 40 in the screw axis direction do not have to be exactly the same, and either may be longer as long as the length is substantially the same.
- it is preferable that the positional relationship between the two is matched and the first region ⁇ is longer than the discharge port 40 as in the present embodiment.
- a part of the blades of the screw is notched so that the developer conveying ability in the first region is lower than the developer conveying ability in the second region.
- the transfer capability can be changed by appropriately adjusting the outer diameter, pitch, angle, etc. of the blades in addition to cutting out the blades in this way.
- the outer diameter of the blade formed spirally around the rotation axis of the conveying screw may be formed so that the first region is smaller than the second region.
- members 41a, 41b, 41c whose outer diameter is smaller than the blades formed in the second region may be installed in the first region.
- the member 41a shown in FIG. 5A is a rectangular rib extending radially from the rotating shaft 25a.
- the member 41b in FIG. 5 (b) is a rib whose cross-sectional shape is substantially elliptical and whose rib cross-section gradually becomes narrower from the root of the rotating shaft 25a to the tip.
- the cross-sectional shape orthogonal to the rotation shaft 25a has the same phase and the same shape along the rotation shaft 25a.
- the member 41c shown in FIG. 5C is a rib that is rectangular and is installed at a slight angle with respect to the rotation shaft 25a.
- FIG. 6 shows a graph of developer discharge characteristics in this embodiment.
- the developer discharge characteristic is a developer discharge amount per unit time when the developer amount in the developer container 22 is a variable.
- the amount of developer in the developer container 22 is determined by balancing the difference between the discharge amount per unit time, the replenishment amount replenished to the developer container 22 per unit time, and the toner amount used for development. That is, the amount of developer in the developing container 22 is indicated by the amount of developer indicated by the intersection a of the minimum supply amount per unit time and the discharge characteristic line, and the intersection b of the maximum supply amount per unit time and the discharge characteristic line. Values between developer amounts can be roughly taken. In other words, this intersection is the point where the developer amount balances between the minimum supply and the maximum supply.
- the developer discharge characteristics can be measured as follows. With the developing sleeve 28 and the first and second conveying screws 25 and 26 driven at desired peripheral speeds, the developer is put into the developing container 22 until the developer is uniformly coated on the developing sleeve 28. The developing sleeve 28, the first and second conveying screws 25, 26 are driven at a desired peripheral speed (usually 1 or 2 minutes) until the developer circulation in the developing container 22 reaches a steady state. When the coating on the developing sleeve 28 becomes uniform, the developer is gradually put into the developing container 22 from the developer supply port 30, and the discharge amount per unit time at that time is measured. In this embodiment, the developer discharge amount per unit time was measured by adding the developer in 10 g increments and measuring the discharge amount for 30 seconds.
- the blade 25b is removed in the first region ⁇ including the facing portion of the discharge port 40 of the first conveying screw 25, so that the second region upstream of the developer conveying direction in the first region ⁇ .
- the developer conveyance performance is lowered with respect to the region ⁇ .
- the developer is retained in the area where the conveyance performance is lowered, and thereby the developer surface is raised, thereby suppressing the jumping of the developer and at the same time realizing the discharge dependent on the agent surface. It is said.
- FIG. 8A shows a case where the developer charge amount is high and the developer fluidity is low
- FIG. 8B shows a case where the developer charge amount is low and the developer fluidity is high.
- the developer surface behavior in a region facing the outlet 40 is shown.
- the solid line arrow in the figure represents the developer conveyance speed at that point. That is, the longer the length of the solid arrow, the faster the conveyance speed.
- a broken arrow indicates the degree of increase in the developer level in the region facing the discharge port 40. The longer the arrow, the greater the degree of increase.
- FIG. 8A when the developer charge amount is high and the developer fluidity is low, the developer conveyance speed in the area facing the discharge port 40 and the conveyance speed in the upstream area are shown. The developer is greatly decelerated and stays in a region facing the discharge port 40. As a result, the surface of the developer rises and the developer discharge is promoted.
- FIG. 8B when the developer charge amount is low and the developer fluidity is high, the speed difference is small, and the force for conveying the developer in the region facing the discharge port is small. Even if it becomes lower, the developer hardly decelerates. Therefore, the developer surface does not rise and the developer discharge is suppressed.
- the main cause is that the force transmitted from the wall surface of the developer container 22 to the developer surface layer is reduced in the developer, and the ability to deform the developer shape is reduced. That is, the toner in the developer exists in a state of being attracted to the carrier by electrostatic force by being charged. Toners and carriers have the same polarity, and toner and carrier have different polarities. The carrier is attracted to another carrier through the toner while receiving a repulsive force by another carrier, and similarly, the toners repel each other while being attracted to each other via the carrier.
- the electrostatic force which is the suction force in this way
- the developer deviates from the motion according to gravity (that is, the fluidity is high).
- the developer is found by the electrostatic force and decreases in fluidity.
- the smaller the electrostatic force that is, the lower the charge amount of the developer, the less the movement according to the gravity is found and the higher the fluidity of the developer.
- the force received by the surface layer of the developer from the wall surface of the developing container 22 is also small.
- the developer discharge amount and the developer replenishment amount continue to increase until the balance is reached, and the developer balance agent amount and the developer overflow limit agent amount are increased.
- the drive speed (screw rotation speed) of the first conveying screw 25 is controlled based on the information. That is, based on the information of the acquisition unit, the case where the charge amount of the developer corresponds to the second charge amount lower than the first charge amount than the case where the charge amount of the developer corresponds to the first charge amount is the first.
- the driving speed for driving the first conveying screw 25 by the second driving motor M2 is increased.
- the humidity of the developer is detected as information on the charge amount of the developer. For this purpose, as shown in FIG.
- the image forming apparatus includes a CPU 50 as a control unit, a memory 51 as a storage unit, a counter 52 that counts the number of formed images, an acquisition unit, and a humidity as a humidity detection unit.
- a detection unit 53 is included.
- the first drive motor M1 that drives the developing sleeve 28 and the second drive motor M2 that drives the first conveying screw 25 are controlled by the CPU 50, respectively.
- the reason why the humidity is used as a parameter is that the charge amount of the developer depends on the humidity of the developer. That is, if the developer humidity increases, the developer charge amount tends to decrease, and if the developer humidity decreases, the developer charge amount tends to increase.
- the driving speed of the first conveying screw 25 is controlled while maintaining the rotation speed ratio of the first and second screws 25 and 26 related to the developer circulation. That is, even when the rotational speed of the first conveying screw 25 facing the discharge port 40 is changed, only the discharge performance near the discharge port 40 is maintained without changing the developer delivery efficiency between the screws 25 and 26. To control. As a result, the developer discharge can be improved without largely degrading the entire developer circulation.
- the screw rotation speed ratio related to the developer circulation may be changed because it can be regarded as substantially constant as long as the difference is about ⁇ 1% of the screw rotation speed.
- the first and second conveying screws 25 and 26 are connected to each other by gears so that the rotation speed ratio is maintained.
- the humidity detector 53 detects information (humidity information) related to the humidity of the developer.
- it has the moisture sensor 54 as a moisture detection means, the temperature sensor 55 as a temperature detection means, and the calculation part 56 as a calculation means.
- the moisture amount sensor 54 detects the moisture amount outside the image forming apparatus.
- the moisture sensor 54 is installed outside the apparatus main body.
- the temperature sensor 55 detects the temperature in the developing container.
- the temperature sensor 55 is installed in the developing container 22.
- the calculation unit 56 calculates the humidity of the developer from the relationship between the temperature detected by the temperature sensor 55 and the moisture amount detected by the moisture amount sensor 54.
- the calculation unit 56 stores a table in which the relationship between the temperature, the amount of moisture and the humidity is set, a calculation formula for obtaining the humidity from the relationship between the temperature and the amount of moisture, and the like. Can be calculated. Note that the calculation of the calculation unit 56 may be performed by the CPU 50. Further, the table and the calculation formula may be stored in the memory 51.
- information on the humidity detected by the humidity detection unit 53 is stored in the memory 51.
- the drive speed of the first conveying screw 25 is controlled by input of an image forming job when the developing device 4 is started up, that is, when the first and second drive motors M1 and M2 are driven off. This is performed when the driving of each of the motors M1 and M2 is turned on.
- a table as shown in Table 1 of the memory 51 is stored. Then, when the developing device 4 is started up (at the timing of switching from OFF to ON or immediately before), the CPU 50 reads out the humidity information at that time from the memory 51, and from the table of Table 1 based on the humidity information, The drive speed (screw rotation speed) of the conveying screw 25 is determined.
- three tables are set as shown in Table 1, and each table can be selected by a user or the like in the service mode.
- Table 2 is the initial setting.
- the screw rotation speed (unit: “rpm”) is set for the developer humidity (relative humidity).
- the table 1 is a mode in which the screw rotation speed is not changed regardless of the humidity of the developer.
- Tables 2 and 3 when the humidity of the developer is the first humidity (for example, 15% or less), when the second humidity is higher than the first humidity (for example, greater than 15%).
- the screw rotation speed is set to be higher. That is, the screw rotation speed is faster when the humidity information detected by the humidity detection unit 53 corresponds to the second humidity higher than the first humidity than when the humidity information corresponds to the first humidity. To do.
- the humidity information used for the screw rotation speed is updated by a command from the CPU 50 at a predetermined timing.
- the predetermined timing includes when the image forming apparatus is turned on, when an image forming job starts, when a predetermined time elapses, etc.
- information on humidity is updated when a predetermined number of images are formed.
- the counter 52 counts the number of images to be formed. If the value counted by the CPU 50 with the counter 52 when the developing device 4 is started is equal to or larger than the predetermined number, the humidity information stored in the memory 51 is updated. . Then, the screw rotation speed is controlled based on the humidity information.
- the number of images formed (number of printed sheets) C (n) at that time is read from the memory 51 and compared with the number of printed sheets Ch whose previous screw rotation speed has been changed by humidity (S1). If C (n) -Ch is 300 sheets or more (Y in S1), the developer humidity at that time is read from the memory 51 and is set as the developer humidity H used for screw rotation speed control (S2). The developer humidity is calculated for each print and stored in the memory 51. Thereafter, the number of printed sheets C (n) at that time is set to the number Ch of the most recent screw rotation speed change (S3), and development driving is started using the developer humidity H stored in the memory 51 (S4).
- the screw rotation speed at developer humidity H is read from the table in Table 1, and the drive of the developing device 4 is started at the screw rotation speed.
- the difference from the number of printed sheets Ch in which the previous screw rotation speed is changed by humidity is less than 300 sheets in S1 (N in S1), the development drive is started using the previous developer humidity H (S4). ). That is, since H is not updated, the robot starts up at the same screw rotation speed as before.
- the screw rotation speed can be changed at a certain frequency (300 or more in this embodiment), and the screw rotation speed can be adjusted to the developer humidity at that time.
- the frequency of the above may be one or more, that is, the screw rotation speed may be changed for each print.
- the actual humidity change of the developer with respect to the humidity change in the developing container is slow, this is not necessary. Then, the above number was used.
- the control of FIG. 10 is performed when the developing device 4 is started up. However, this control is performed at other timing, for example, between images during execution of an image forming job (paper Etc.).
- the control of FIG. 10 is accompanied by a change in screw rotation speed due to a change in humidity, it is preferable to perform the control when the developing device 4 is started up. That is, since it is relatively difficult to change the screw rotation speed while the developing device 4 is being driven, the speed can be easily changed by starting up at the speed changed when the drive is started.
- development drive OFF / ON is forcibly executed once every predetermined number of image formation sheets (for example, 150 to 170 sheets) even during execution of an image formation job. ing. For this reason, the control in FIG. 10 is entered at a certain frequency regardless of the number of images formed in the image forming job.
- the driving speed of the first conveying screw 25 is controlled to be high in a state where the charge amount that increases the fluidity of the developer is low, that is, in the state where the humidity of the developer is high.
- the developer surface can be raised to appropriately discharge the developer.
- the screw rotation speed is increased, even when the developer fluidity is high, the developer loses the conveying force at the staying portion facing the discharge port, and the developer that has become slightly slower comes from behind. The developer surface hits and the developer surface rises due to its kinetic energy. For this reason, the developer can be appropriately discharged from the discharge port 40.
- 11 and 12 show the results of experiments conducted to confirm the effects of this embodiment.
- the experiment was carried out in a comparative example in which the screw rotation speed was constant regardless of the developer humidity, and in Example 1 in which the screw rotation speed was changed according to the developer humidity as in this embodiment. Performed under conditions.
- a plurality of images DUTY were shaken, the developing device was driven in an environment where the developer humidity was different, and the amount of developer in the developing container was compared.
- 11 and 12 show the developer amount
- FIG. 11 shows the result of the comparative example
- FIG. 12 shows the result of the example 1.
- the screw rotation speed was fixed at 700 (rpm).
- the screw rotational speed was controlled using the table 2 of Table 1.
- the image DUTY is the ratio of the total amount of toner on the photosensitive drum of the image to the maximum total amount of toner on the photosensitive drum per image, expressed as 100 minutes.
- the maximum total amount of toner is the amount of toner consumed when the entire surface of an image-formable area on the photosensitive drum is developed with toner (full area solid development), and the image DUTY during full area solid development is 100%.
- the developer amount greatly varies depending on the humidity.
- the developer humidity is 60%
- the developer discharge amount is remarkably lowered, and the developer amount is remarkably increased as compared with when the humidity is 10% in order to compensate for this with the agent amount in the developing container.
- the broken lines in FIGS. 11 and 12 represent the limit line of the developer overflow. If the developer humidity is high, the charge amount decreases and the bulk decreases, so the overflow limit line also shifts toward the larger developer amount. The increase in the developer amount due to poor developer discharge at high humidity is greater.
- the screw rotation speed is controlled according to the developer humidity, thereby promoting the discharge performance of the developer at a low charge amount in a high humidity environment and improving the robustness against the overflow of the developer. I let you.
- the charge amount of the developer greatly depends not only on the environment but also on the image DUTY. Therefore, in this embodiment, the developer discharge is improved by controlling the screw rotation speed in accordance with the image DUTY. Since other configurations and operations are the same as those in the first embodiment described above, overlapping illustrations and descriptions are omitted or simplified, and the same components are denoted by the same reference numerals. A description will be given centering on differences from the embodiment.
- the reason why the charge amount of the developer is changed in the image DUTY is that the stirring time distribution of the toner in the developing container 22 varies depending on the stirring time in the developing container 22 with respect to the replenished toner amount. That is, when images having a high image DUTY are continuously printed, most of the toner in the developing container 22 is developed, and new toner is replenished instead. At this time, the higher the DUTY, the more toner is replenished in a short time. Therefore, most of the stirring time distribution of the toner in the developing container 22 is short, and the charge amount as a whole decreases due to insufficient stirring. Conversely, when low DUTY images are printed continuously, the toner is hardly replaced, and the toner stirring time distribution in the developing container 22 is mostly long. Therefore, the charge amount as a whole increases.
- the image DUTY is used as information on the charge amount of the developer.
- the image forming apparatus of the present embodiment includes a CPU 50 as a control unit, a memory 51 as a storage unit, a counter 52 that counts the number of image formations, and a video count unit 57 as shown in FIG.
- the counter 52 and the video count unit 57 constitute a toner consumption amount detection unit 58 as an acquisition unit and toner consumption amount detection means.
- the video count unit 57 integrates the number of image dots formed on the photosensitive drum, that is, the video count. For example, the level (0 to 255 level) for each pixel of the input image data (for example, at 600 dpi) is integrated for one image. Further, the counter 52 counts the number of image formations, adds up the video counts for a certain number of image formations, and divides this by the value obtained by multiplying the number of image formations by a video count of 100% DUTY to obtain the average image DUTY. Desired. That is, the average image DUTY is an average image DUTY of a certain number of image formations, and corresponds to a value related to a toner consumption amount that is consumed along with image formation per unit time.
- the toner consumption amount detection unit 58 calculates the average image DUTY.
- the information that the toner consumption amount detection unit 58 calculates the average image DUTY (toner consumption amount) is stored in the memory 51. Also in this embodiment, when the developing device 4 is started up (when switching from OFF to ON), the CPU 50 reads the average image DUTY at that time from the memory 51, and based on the information, from the table in Table 2. The drive speed (screw rotation speed) of the first conveying screw 25 is determined. In this embodiment, three tables are set as shown in Table 2, and each table can be selected by a user or the like in the service mode. Table 2 is the initial setting.
- the screw rotation speed (unit: “rpm”) is set for the average image DUTY.
- the table 1 is a mode in which the screw rotation speed is not changed regardless of the average image DUTY.
- the case where the average image DUTY (toner consumption amount) corresponds to the second consumption amount larger than the first consumption amount is greater than the case where the average image DUTY (toner consumption amount) corresponds to the first consumption amount.
- the screw rotation speed is set to be high.
- the screw rotation speed Becomes 800 rpm or more.
- the average image DUTY used for the screw rotation speed is calculated at the time when a predetermined number of images have been formed. For this purpose, the number of image formations is counted by the counter 52, and if the value counted by the CPU 50 by the counter 52 when the developing device 4 is started is equal to or greater than the predetermined number, the average image DUTY is calculated and stored in the memory 51. Then, the screw rotation speed is controlled based on the average image DUTY. Therefore, in the case of the present embodiment, the average image DUTY is an average of the images DUTY from the update (that is, control) of the screw rotation speed to the next update.
- b_max is the number of image dots in the case of A4, 100% image DUTY at the time of printing one sheet.
- the average image DUTY ⁇ D> obtained in S12 is stored in the memory 51 (S13), and the accumulated dot number B is cleared to zero for calculation of the next average image DUTY (S14). Thereafter, the number of printed sheets C (n) at that time is set to the latest number Cd of which the screw rotation speed is changed by the average image DUTY (S15), and development driving is performed using the average image DUTY ⁇ D> stored in the memory 51.
- Start up S16
- the screw rotation speed of the average image DUTY ⁇ D> is read from the table in Table 2, and the driving of the developing device 4 is started at the screw rotation speed.
- the development drive is started using the previous average image DUTY ⁇ D>. (S16). That is, since ⁇ D> has not been updated, it is started at the same screw rotation speed as before.
- the screw rotation speed can be updated at a certain frequency (1000 or more in this embodiment), and the screw rotation speed can be adjusted to the average image DUTY at that time.
- the driving speed of the first conveying screw 25 is high in a state where the charge amount at which the developer fluidity is high is low, that is, in a state where the average image DUTY is high (toner consumption is high). Controlled to be faster. Therefore, as in the first embodiment, even if the developer has high fluidity and the developer is unlikely to stay in the vicinity of the discharge port 40, the developer surface is raised and the developer is appropriately discharged. Yes.
- FIGS. 11 and 15. 11 and 15 show the results of experiments conducted to confirm the effects of this embodiment.
- the experiment was performed in a comparative example in which the screw rotation speed was constant regardless of the average image DUTY, and in Example 2 in which the screw rotation speed was changed according to the average image DUTY as in the present embodiment. Performed under conditions. First, a plurality of images DUTY were shaken, the developing device was driven in an environment where the developer humidity was different, and the amount of developer in the developing container was compared. 11 and 15 show the developer amount, FIG. 11 shows the result of the comparative example, and FIG. 15 shows the result of the example 2. Moreover, in the comparative example, the screw rotation speed was fixed to 700 (rpm). In Example 2, the screw rotation speed was controlled using Table 2 in Table 2.
- the developer amount varies depending on the average image DUTY.
- the average image DUTY is 100%
- the developer discharge amount is remarkably lowered, and the developer amount is increased compared to when the humidity is 0% in order to compensate for this with the agent amount in the developing container.
- this tendency depends on the developer humidity as described in Example 1, and is particularly remarkable in a high humidity environment.
- the image DUTY is higher, and the higher the humidity, the less the robustness against the developer overflow, and there is a risk that the developer overflows due to a momentary change in the developer surface such as development drive OFF / ON. growing.
- Example 2 since the screw rotation speed is controlled by the average image DUTY as shown in FIG. 15, the variation in the discharge amount due to the image DUTY is suppressed, and the developer amount at 0% -100%. The variation is small throughout the humidity environment. Therefore, it can be seen that the robustness is improved against the overflow of the developer as compared with the comparative example.
- the screw rotation speed is controlled in accordance with the developer humidity or the average image DUTY, respectively, thereby promoting the discharge performance of the developer at a low charge amount, and against the developer overflow. Improved robustness.
- the developer discharge is further improved by controlling the screw rotation speed in accordance with the two parameters of the developer humidity and the image DUTY. Since other configurations and operations are the same as those in the first and second embodiments described above, overlapping illustrations and descriptions are omitted or simplified, and the same components are denoted by the same reference numerals, and the following. The description will focus on the differences from the first and second embodiments.
- the image forming apparatus includes a CPU 50 as a control unit, a memory 51 as a storage unit, a counter 52 that counts the number of image formations, an acquisition unit, and a humidity as a humidity detection unit.
- a detection unit 53 and a video count unit 57 are included.
- the counter 52 and the video count unit 57 constitute a toner consumption detection unit 58 as an acquisition unit and a toner consumption detection unit.
- the humidity detector 53 includes a moisture sensor 54 as a moisture detector, a temperature sensor 55 as a temperature detector, and a calculator 56 as a calculator. The configuration and operation of each part are the same as those in the first and second embodiments.
- the CPU 50 causes the humidity detection unit 53 to perform image formation on the first or more recording materials since the humidity (humidity information) detected by the humidity detection unit 53 was previously stored in the memory 51.
- the detected humidity (humidity information) is stored in the memory 51. That is, the humidity information in the memory 51 is updated.
- the CPU 50 since the CPU 50 stores the average image DUTY detected by the toner consumption amount detection unit 58 in the memory 51 last time, the toner consumption amount detection unit 58 detects that an image has been formed on a second or more number of recording materials.
- the average image DUTY is stored in the memory 51.
- the second number is different from the first number and is larger than the first number.
- the first number is 300 and the second number is 1000.
- the CPU 50 controls the second drive motor M2 based on the speed set based on the relationship between the humidity (humidity information) stored in the memory 51 and the average image DUTY (toner consumption).
- the driving speed (screw rotational speed) of the first conveying screw 25 is determined from the table in Table 3. Further, in this embodiment, three tables are set as shown in Table 3, and each table can be selected by the user or the like in the service mode. Table 2 is the initial setting.
- the reason why a plurality of tables are provided in the service mode as shown in Table 3 is to allow a more appropriate table to be selected in accordance with a specific user or region (environment).
- the screw rotation speed (unit: “rpm”) is set for the developer humidity and the average image DUTY.
- the table 1 is a mode in which the screw rotation speed is not changed regardless of the developer humidity and the average image DUTY.
- the humidity of the developer is the first humidity (for example, 15% or less)
- the second humidity is higher than the first humidity (for example, greater than 15%).
- the screw rotation speed is set to be higher.
- the average image DUTY toner consumption
- the average consumption DUTY toner consumption
- the average consumption DUTY toner consumption
- the average consumption DUTY toner consumption
- the number of images formed at that time (number of printed sheets) C (n) is read from the memory 51 and compared with the number of printed sheets Ch in which the developer humidity H in the previous memory 51 is updated ( S21). If C (n) -Ch is 300 sheets or more (Y in S21), the developer humidity at that time is read from the memory 51 and is set as the developer humidity H used for screw rotation speed control (S22). The developer humidity is calculated for each print and stored in the memory 51. Thereafter, the number of printed sheets C (n) at that time is set to the number Ch of updated developer humidity H most recently (S23), and the process proceeds to the next S24. On the other hand, if C (n) -Ch is less than 300 sheets in S21 (N in S21), the developer humidity H is not updated and the process proceeds to the next S24 as it is.
- the number of prints C (n) read from the memory 51 is compared with the number of prints Cd obtained by updating the previous average image DUTY in the memory 51 (S24). If C (n) -Ch is 1000 sheets or more (Y in S24), the cumulative image dot number B at that time obtained by separate calculation is read from the memory. Then, by dividing by b_max (C (n) ⁇ Cd), an average image DUTY ⁇ D> per one print from the previous update of the average image DUTY to that time is obtained (S25).
- the average image DUTY ⁇ D> obtained in S25 is stored in the memory 51 (S26), and the accumulated dot number B is cleared to zero for calculation of the next average image DUTY (S27). Thereafter, the print number C (n) at that time is set as the latest number Cd of the updated average image DUTY (S28), and development driving is performed using the developer humidity H and the average image DUTY ⁇ D> stored in the memory 51. (S29). That is, the developer humidity H and the screw rotation speed of the average image DUTY ⁇ D> are read from the table of Table 3, and the driving of the developing device 4 is started at the screw rotation speed.
- FIGS. 11 and 18 show the results of experiments conducted to confirm the effect of this embodiment.
- the screw rotation speed is constant regardless of the developer humidity and the average image DUTY, and the screw rotation speed is changed according to the developer humidity and the average image DUTY as in this embodiment.
- each was performed under the following conditions.
- a plurality of images DUTY were shaken, the developing device was driven in an environment where the developer humidity was different, and the amount of developer in the developing container was compared.
- 11 and 18 show the developer amount
- FIG. 11 shows the result of the comparative example
- FIG. 18 shows the result of the example 3.
- the screw rotation speed was fixed to 700 (rpm).
- Example 3 the screw rotation speed was controlled using Table 2 in Table 3.
- Example 3 the screw rotation speed is controlled by two parameters of developer humidity and average image DUTY, so that it is more effective than the cases of Example 1 and Example 2. In addition, variation in emissions was suppressed. As a result, in Example 3, the robustness against the developer overflow is further improved. ⁇ Fourth Embodiment>
- a fourth embodiment of the present invention will be described with reference to FIGS. 19 and 20 with reference to FIG.
- the developer discharge performance in a high humidity environment and a high image DUTY is promoted, and the developer overflows.
- Improved robustness against when the temperature and humidity surrounding the developer changes rapidly, the developer humidity cannot immediately follow the change, and gradually becomes an environment around the developer with some delay. For this reason, for some time after the change in temperature and humidity around the developer, there is a discrepancy between the state of the developer (charge amount) that should be and the state (charge amount) detected and determined as described above. It is possible to get up.
- the humidity of the developer and the image DUTY are used as information on the charge amount of the developer.
- the image forming apparatus of the present embodiment also includes a CPU 50, a memory 51, a counter 52, a humidity detector 53, and a video count unit 57, as shown in FIG.
- the counter 52 and the video count unit 57 constitute a toner consumption amount detection unit 58
- the humidity detection unit 53 includes a moisture amount sensor 54, a temperature sensor 55, and a calculation unit 56.
- the configuration and operation of each part are the same as those in the first and second embodiments.
- the CPU 50 controls the screw rotation speed based on the humidity (humidity information) stored in the memory 51 and the average image DUTY.
- the humidity detected by the humidity detector 53 at a predetermined timing greatly changes with respect to the humidity stored in the memory 51
- the development in the memory 51 is performed for a while. Do not update the agent humidity information. That is, the humidity (humidity information) detected this time is a predetermined humidity range (corresponding to) the humidity range higher than the low humidity category (corresponding to) Yes) Consider the case of changing to a high humidity category.
- the humidity stored in the memory 51 is not updated from when the change occurs until image formation is performed on a predetermined number of recording materials. That is, the screw rotation speed is controlled using the humidity as it was last time.
- the humidity stored in the memory 51 is updated to the humidity detected at that time, and the screw rotation speed is controlled using the humidity.
- the screw rotation speed is not changed immediately, and the screw rotation is continued until a predetermined number (500 in this embodiment) is printed. Keep speed. Thereafter, the screw rotation speed is changed according to the detected humidity when the first development drive after turning over 500 sheets is turned OFF / ON.
- the humidity classification of the present embodiment is the classification shown in Table 3 above, and is divided into three classifications. That is, the first category is “15% or less”, the second category is “greater than 15% and 45% or less”, and the third category is “greater than 45%”. Therefore, when the humidity detected this time changes from the low humidity classification that is the predetermined humidity range to the high humidity classification that is higher than the low humidity classification relative to the previously detected humidity, Become. That is, when the humidity detected last time is the range of the first category and the humidity detected this time is the range of the second category or the third category, or the previously detected humidity is the range of the second category. In this case, the humidity detected this time falls within the range of the third category. In this case, the screw rotation speed is not changed immediately, but the screw rotation speed is kept as it is until a predetermined number of sheets are printed.
- the screw rotation speed control if the developer humidity determined by the detection of the temperature sensor or the moisture amount sensor and the actual developer humidity are unmatched, the most harmful effects are as follows. That is, the developer is not so high in humidity, but the detected and determined humidity is high, and the developer is driven at a rotational speed faster than the screw rotational speed that is supposed to be, resulting in excessive developer discharge. This is because the rate at which the developer decreases due to excessive developer discharge is generally high, and the developer is quickly depleted, and sufficient developer is not supplied to the developing sleeve, which is likely to cause image defects such as density unevenness. Because.
- the humidity classification is switched from high humidity to low humidity by the detection of the temperature sensor or moisture sensor, it is as follows. That is, even if the detected developer humidity does not match the actual developer humidity, the detected humidity is low even though the developer is not so low. In this case, the developer is driven at a rotation speed lower than the screw rotation speed that should be originally formed, resulting in a developer discharge failure. As described above, this situation is serious if it continues for a long period of time, but the developer humidity detected according to the screw drive and the actual developer humidity gradually match. There is little risk of overflow due to increase. Therefore, in this case, it is not necessary to execute control that does not change the screw rotation speed, such as when switching from low humidity to high humidity.
- FIG. 19 A specific example of control according to the present embodiment will be described with reference to FIGS. 19 and 20. Also in this embodiment, the flowchart of FIG. 19 is executed every time the developing device 4 is started (OFF / ON), and driving is started at the screw rotation speed obtained thereby. That is, also in this embodiment, the change timing of the screw rotation speed is the timing of development drive OFF / ON.
- the flow of FIG. 19 has many parts in common with the flow of FIG. 17 described above, so the description of the same steps will be omitted or simplified, and FIG. 19 will be described with a focus on the parts different from the flow of FIG. To do.
- the screw rotation speed classification has changed from the classification (900 rpm) of “humidity 15% -45%, average image DUTY 20% -50%” to a higher humidity classification (for example, humidity 60%).
- K 1 and the developer humidity H is not updated.
- the screw rotation speed classification is “humidity 15% ⁇ 45. %, Average image DUTY 50% or more ".
- the number of formed images is counted in order to update the developer humidity H and the average image DUTY ⁇ D>, and to release the flag K. It may be. Further, although the drive sources for the developing sleeve and the conveying screw are different from each other, they may be the same drive source.
- the developing chamber 23 having the function of supplying the developer to the developing sleeve 28 and the stirring chamber 24 having the function of collecting the developer from the developing sleeve 28 are separately provided vertically.
- a stirring type developing device was used.
- the present invention can also be applied to an image forming apparatus provided with a developing device other than such a configuration.
- the developing chamber 23 and the stirring chamber 24 are arranged horizontally.
- the developing device can also be used.
- an image forming apparatus capable of appropriately discharging the developer by raising the surface of the developer even if the developer has high fluidity and the developer is unlikely to stay in the vicinity of the discharge port.
- Temperature sensor temperature detection means
- Calculation unit calculation means
- / 57 ...
- Video count unit / 58 Toner consumption detection Part (acquisition part, toner consumption detection means) / 100... Image forming apparatus / 1 ... the first drive motor / M2 ... second driving motor (driving means) / alpha ... first region / beta ... second region
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Abstract
Description
前記搬送スクリューは、前記排出口に対向する部分を含む第1領域の外径が、前記第1領域に隣接する第2領域の外径よりも小さくなるように形成されており、前記制御部は、前記取得部の情報に基づいて、現像剤の帯電量が第1の帯電量に対応する場合よりも、前記第1の帯電量よりも低い第2の帯電量に対応する場合の方が、前記駆動装置により前記搬送スクリューを駆動する駆動速度が速くなるように制御する画像形成装置が提供される。
図2は第1の実施形態に係る現像装置の概略構成横断面図。
図3は同じく概略構成縦断面図。
図4は第1の実施形態に係る現像装置の排出口近傍の搬送スクリューを示す模式図。
図5は第1の実施形態に係る現像装置の排出口近傍の搬送スクリューの他の3例を示す模式図。
図6は現像剤の排出口からの排出特性を示す図。
図7は排出口近傍の現像剤の剤面を示す模式図。
図8の(a)は現像剤の流動性が低い場合の、(b)は現像剤の流動性が高い場合の、それぞれ排出口近傍の現像剤の剤面を示す模式図。
図9は第1の実施形態に係る画像形成装置の制御ブロック図。
図10は第1の実施形態の現像装置の立ち上げ時の制御のフローチャート。
図11は本発明の比較例における、各画像DUTYの現像剤湿度に対する現像容器内の現像剤量の変化を示す図。
図12は本発明の実施例1における、各画像DUTYの現像剤湿度に対する現像容器内の現像剤量の変化を示す図。
図13は本発明の第2の実施形態に係る画像形成装置の制御ブロック図。
図14は第2の実施形態の現像装置の立ち上げ時の制御のフローチャート。
図15は本発明の実施例2における、各画像DUTYの現像剤湿度に対する現像容器内の現像剤量の変化を示す図。
図16は本発明の第3の実施形態に係る画像形成装置の制御ブロック図。
図17は第3の実施形態の現像装置の立ち上げ時の制御のフローチャート。
図18は本発明の実施例3における、各画像DUTYの現像剤湿度に対する現像容器内の現像剤量の変化を示す図。
図19は本発明の第4の実施形態の現像装置の立ち上げ時の制御のフローチャート。
図20は図19のフローでK=1となった場合の別のフローを示すフローチャート。
図21は本発明の他の実施形態の第1例の現像装置の概略構成横断面図。
図22は本発明の他の実施形態の第2例の現像装置の概略構成横断面図。
[画像形成装置]
[現像装置]
[現像剤]
[現像剤補給]
[現像剤排出]
[スクリュー回転速度の制御]
<第2の実施形態>
<第3の実施形態>
<第4の実施形態>
<他の実施形態>
Claims (8)
- 像担持体と、
前記像担持体に形成された潜像を現像する現像装置であって、現像剤が収容された現像容器と、前記現像容器内で現像剤を搬送する搬送スクリューと、前記搬送スクリューと対向するように前記現像容器の側面に設けられ、前記現像容器内の余剰現像剤を排出するための排出口と、を備えた現像装置と、
前記現像容器に現像剤を補給する補給装置と、
前記搬送スクリューを回転駆動する駆動装置と、
現像剤の帯電量に関する情報を取得する取得部と、
前記駆動装置を制御する制御部と、を備え、
前記搬送スクリューは、前記排出口に対向する部分を含む第1領域の外径が、前記第1領域に隣接する第2領域の外径よりも小さくなるように形成されており、
前記制御部は、前記取得部の情報に基づいて、現像剤の帯電量が第1の帯電量に対応する場合よりも、前記第1の帯電量よりも低い第2の帯電量に対応する場合の方が、前記駆動装置により前記搬送スクリューを駆動する駆動速度が速くなるように制御する画像形成装置。 - 前記搬送スクリューは、回転軸と前記回転軸の周囲に螺旋状に形成した羽根を備え、前記第1領域には、前記羽根部が形成されていない請求項1に記載の画像形成装置。
- 前記搬送スクリューは、回転軸の周囲に螺旋状に形成した羽根の外径が、前記第2領域よりも前記第1領域の方が小さくなるように形成される請求項1に記載の画像形成装置。
- 前記制御部は、前記駆動装置の立ち上げ時に前記取得部からの情報に基づいて前記駆動装置を制御する請求項1ないし3のうちの何れか1項に記載の画像形成装置。
- 像担持体と、
前記像担持体に形成された潜像を現像する現像装置であって、現像剤が収容された現像容器と、前記現像容器内で現像剤を搬送する搬送スクリューと、前記搬送スクリューと対向するように前記現像容器の側面に設けられ、前記現像容器内の余剰現像剤を排出するための排出口と、を備えた現像装置と、
前記現像容器に現像剤を補給する補給装置と、
前記搬送スクリューを回転駆動する駆動装置と、
現像剤の湿度に関する情報を取得する取得部と、
前記駆動装置を制御する制御部と、を有し、前記搬送スクリューは、前記排出口に対向する部分を含む第1領域の外径が、前記第1領域に隣接する第2領域の外径よりも小さくなるように形成され、
前記制御部は、前記取得部により取得された情報に基づき、前記現像剤の湿度が第1の湿度に対応する場合よりも、前記第1の湿度よりも高い第2の湿度に対応する場合の方が、前記駆動装置により前記搬送スクリューを駆動する駆動速度が速くなるように制御する画像形成装置。 - 前記制御部は、画像形成枚数が所定枚数行われる毎に、前記取得部により取得された情報に基づいて、前記搬送スクリューを駆動する駆動速度を制御する、
ことを特徴とする、請求項5に記載の画像形成装置。 - 前記取得部は、前記現像容器内の温度を検知する温度センサと、装置の外部の水分量を検知する水分量センサと、を有する請求項5又は6に記載の画像形成装置。
- 像担持体と、
前記像担持体に形成された潜像を現像する現像装置であって、現像剤が収容された現像容器と、前記現像容器内で現像剤を搬送する搬送スクリューと、前記搬送スクリューと対向するように前記現像容器の側面に設けられ、前記現像容器内の余剰現像剤を排出するための排出口と、を備えた現像装置と、
前記現像容器に現像剤を補給する補給装置と、
前記搬送スクリューを回転駆動する駆動装置と、
単位時間あたりに画像形成に伴って消費されるトナー消費量に関する値を取得する取得部と、前記駆動装置を制御する制御部と、を有し、
前記搬送スクリューは、前記排出口に対向する部分を含む第1領域の外径が、前記第1領域に隣接する第2領域の外径よりも小さくなるように形成されており、
前記制御部は、前記取得部により取得された情報に基づき、前記トナー消費量に関する値が第1の消費量に対応する場合よりも、前記第1の消費量よりも多い第2の消費量に対応する場合の方が、前記駆動手段により前記搬送スクリューを駆動する駆動速度が速くなるように制御する画像形成装置。
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JP7009918B2 (ja) * | 2017-10-30 | 2022-01-26 | コニカミノルタ株式会社 | 現像装置及び画像形成装置 |
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CN106415406B (zh) | 2020-06-09 |
US9946191B2 (en) | 2018-04-17 |
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