Abstract: This is a test procedure for detecting contaminants or a method for removing contaminants from toner to be used in an electrophotographic marking system. The method simulates the mixing and separation of contaminants that occur in an actual development system. It has been determined that contaminants in toner have tribo properties that prevent strong adherence of these contaminants to the carrier whereas purified toner has tribo properties that permit stronger adherence to the carrier. A separation procedure and method is thereby used to remove or identify contaminants.

Abstract: An electrophotographic printing machine of the type in which an electrostatic latent image recorded on a charge retentive surface is developed with toner particles to form a visible image thereof, including: a toner dispenser; a donor member for transporting toner from the housing to a development zone; and a cyclone separator system, connected to the toner dispenser, for separating the toner and supplying toner particles of a predefined size into the housing.

Abstract: An image forming apparatus collects toner remaining on a photoconductive drum after a toner image is transferred to paper, and collects the impurities (paper dust) included in the toner collected in an image forming apparatus which reuses the collected toner by a mixer provided in a developer container. An auxiliary collecting member is provided in a gap between first feed blades and second feed blades in an impurity collector.

Abstract: Methods of manufacturing toner for use in electrophotographic imaging members, such as photoreceptor structures. More particularly, embodiments pertain to an apparatus and process for separating toner from toner/carrier mixtures, such as reclaiming toner from waste toner, much more efficiently and with improved yields.

Abstract: This is a magnetic developer purification structure that is used along with other stations positioned in the path of an electrostatic moving belt or drum in an electrostatic marking system. This purification structure may be a separate station or may be part of the development station provided it supplies purified developer to the development station prior to developer contacting the latent image on the drum or belt. The purification structure will agitate the developer mix to form a homogenous mixture of toner and carrier. This mixture is magnetically treated to separate less magnetically attracted contaminants from the remainder of the mixture. The contaminants are removed from the mix and substantially pure developer is then available for contact with the latent image.

Abstract: This is a test procedure for detecting contaminants or a method for removing contaminants from toner to be used in an electrophotographic marking system. The method simulates the mixing and separation of contaminants that occur in an actual development system. It has been determined that contaminants in toner have tribo properties that prevent strong adherence of these contaminants to the carrier whereas purified toner has tribo properties that permit stronger adherence to the carrier. A separation procedure and method is thereby used to remove or identify contaminants.

Abstract: In a case where there are developers belonging to Life Rank 1 representing a service life substantially as long as that of a fresh developer (Step S501), and the developers includes one which is ready to print (Step S502), it is determined that image formation can be performed without performing a preparatory operation (Step S506). In a case where there is no print-ready developer but a developer which requires an agitation operation of rotating a developing roller by a predetermined quantity (Step S503), the agitation operation is performed on the developer (Step S504) so as to make the developer in a print-ready state. In a case where the developer cannot be made print-ready by the agitation operation, a density control operation for adjusting operating conditions of an apparatus is performed (Step S505). Thus is obviated an unnecessary operation. The developer subjected to a predetermined print preparatory process is used in a printing operation so that an image of good quality may be formed.

Abstract: A method of preparing toner includes preparing a pigment dispersion solution by dispersing a pigment in a mixed surfactant solution composed of an anionic reactive surfactant and a nonionic reactive surfactant, mixing the pigment dispersion solution with a polymer latex prepared by polymerizing a toner composition comprising an amphiphilic macromonomer having at least one reactive functional group at an end thereof and at least one polymerizable monomer, and adding an inorganic salt to a mixed solution of the polymer latex and the pigment dispersion solution to be agglomerated, wherein a shape of toner particles can be controlled to have circularity of 0.5-1.0 by adjusting an amount of the nonionic reactive surfactant to be 20-100 parts by weight based on 100 parts by weight of the anionic reactive surfactant. In addition, a method of forming an image uses the toner, and an image forming apparatus to form an image employs the toner.

Abstract: Controlling the charge on toner in a development station of an electrographic reproduction apparatus, wherein data relative to latent image charge carrying member voltage and image density control patches are sensed and development potential to achieve an aim density is calculated therefrom. A delta from an optimum development potential range is calculated, and in response to the determined delta, an amount of liquid charge control agent, from a supply of suitable liquid charge control agent, necessary to be added to the developer material in the development station to bring the toner to substantially a charge level that will enable a desired optimum developer potential is calculated. The calculated amount of liquid charge control agent is then injected directly into the development station.

Abstract: Controlling the charge on toner in a development station of an electrographic reproduction apparatus, wherein data relative to latent image charge carrying member voltage and image density control patches are sensed and development potential to achieve an aim density is calculated therefrom. A delta from an optimum development potential range is calculated, and in response to the determined delta, an amount of liquid charge control agent, from a supply of suitable liquid charge control agent, necessary to be added to the developer material in the development station to bring the toner to substantially a charge level that will enable a desired optimum developer potential is calculated. The calculated amount of liquid charge control agent is then injected directly into the development station.

Abstract: An image forming member includes: an electrostatic latent image holding member that holds an electrostatic latent image; a developing unit that develops a toner image formed by a toner on a surface of the electrostatic latent image holding member; a toner removing member that removes a residual toner remaining on a surface of the electrostatic latent image holding member; a conveying path including a conveying member that is internally provided in the conveying path and that returns the residual toner removed from the surface of the electrostatic latent image holding member to the developing unit; and a trapping portion that traps a foreign matter conveyed by the conveying member, the electrostatic latent image holding member, the developing unit, the toner removing member, the conveying path, and the trapping portion of the image forming member being integrally and detachably attached to an image forming apparatus body.

Abstract: A developing device includes (a) a developing member; (b) a developer container; (c) a partition member that partitions an interior of the developer container into a primary chamber and a secondary chamber; and (d) a developer-conveying unit that is disposed in the primary chamber, the developing device defining a collected-toner-receiving port through which a collected toner that is collected from a toner image carrier is received into the developer container; and a migration opening through which a developer held in the primary chamber is migratable to the secondary chamber, the developing device further including (e) a capturing unit that is disposed at the migration opening and captures a foreign material which migrates through the migration opening together with the developer; and (f) a foreign-material-removing unit that is disposed at the developer-conveying unit and moves the foreign material out of the developer container in accordance with the rotation of the developer-conveying.

Abstract: A substrate transport device includes a chamber, a rotary wheel, a first magnet, a carrier, and a second magnet. The rotary wheel is disposed outside the chamber. The first magnet is disposed on the rotary wheel. The carrier is disposed in the chamber. The second magnet is disposed on the carrier.

Abstract: An electrophotographic printing machine of the type in which an electrostatic latent image recorded on a charge retentive surface is developed with toner particles to form a visible image thereof, including: a toner dispenser; a donor member for transporting toner from the housing to a development zone; and a cyclone separator system, connected to the toner dispenser, for separating the toner and supplying toner particles of a predefined size into the housing.

Abstract: An electrophotographic printing machine of the type in which an electrostatic latent image recorded on a charge retentive surface is developed with toner particles to form a visible image thereof, including: a housing having a supply of toner and developer therein; a donor member for transporting toner from the housing to a development zone; a first manifold, adjacent to the donor member, having an air stream for removing toner emission; a second manifold, adjacent to the donor member, having an air stream for removing toner emission; and a cyclone separator system, connected to the first manifold and the second manifold, for separating the toner from the air stream and returning toner particles of a predefined size back into the housing.

Abstract: A developing unit using a two-component developer intended to provide an image forming apparatus capable of forming a high-quality image for a long period of time. A developing unit using a developer contains toner, carrier and opposite polarity particles having a polarity opposite to the charging polarity of toner includes separation means for separating the toner or opposite polarity particles, and control mechanism for controlling opposite polarity particle separation ratio in response to the image area ratio and the number of prints.

Abstract: The toner according to the present invention may be produced from a toner raw composition which comprises a foaming agent, a binder resin and a colorant, wherein the colorant comprises a black metal compound, the foaming agent has a volume-average particle diameter of 2 ?m to 50 ?m, the toner raw composition turns into a porous mixture while the foaming agent expands at melting and kneading the toner raw composition, and the toner obtained through milling and classifying the porous mixture has a specific density of 1.0 g/cm3 to 1.3 g/cm3, wherein the specific density is determined as follows: 1 gram of toner is pressed at 400 kgf/cm2 for five minutes in a discal cavity having a diameter of 20 mm, then the discal toner is removed; the discal toner volume (V) is calculated from the diameter and height, measured at 10 minutes after releasing the pressure on the discal toner, and the discal toner mass (W) is measured; then the specific density is determined from the following formula: Specific Density (?T)=W/V.

Abstract: An image forming apparatus includes a latent-image carrier, a developing unit, a transfer unit, a cleaning unit, a recovered-toner supply unit, and a foreign-matter collecting unit. The developing unit carries a developer containing a toner and develops an electrostatic latent image on the latent-image carrier with the toner. The transfer unit transfers the toner developed on the latent-image carrier to a recording material directly or via an intermediate transfer body. The cleaning unit removes a toner remaining on at least one of the latent-image carrier and the intermediate transfer medium after the transfer. The recovered-toner supply unit supplies a toner removed by the cleaning unit to the developing unit again. The foreign-matter collecting unit collects a foreign matter, which is mixed into the toner supplied from the recovered-toner supply unit and moved onto the latent-image carrier by the developing unit, before the transfer by the transfer unit.

Abstract: Sieve screen level sensing in a filtering apparatus (10) for filtering fine powder material (M) which includes a sieve (12) having a material inlet (24) and a material outlet (26), and a sieve screen (14) is disposed within the sieve (12) between the material inlet (24) and outlet (26) such that the material (M) must pass through the sieve screen (14) to enter the material outlet (26) and thereby exit the sieve (12). An input valve (22) controls the flow of material (M) into the sieve (12) through the material inlet (24). A sieve screen level sensor assembly (20) senses a level of material (M) accumulated upon the sieve screen (14), and issues a level sense signal (66) indicative of that level. A programmable logic controller (60) receives the level sense signal (66) and controls the inlet valve (22) dependent at least in part thereon to thereby control the flow of material (M) into the material inlet (24).

Abstract: A toner agitating device feeds air from an air feeding device to the inside of a toner container storing powdery toner therein to thereby agitate the toner. The air feeding device is implemented by at least one variable air pump capable of varying the amount of air to be fed for a unit time.

Abstract: A toner separation apparatus includes a target, an inlet through which toner laden carrier enters to strike the target, an exit for carrier particles below the target, and an exit for toner particles downstream of the target. A filter can be positioned between the target and the toner exit, and a mesh to which the target is attached can be located between the inlet and the filter. The toner-laden carrier can be entrained by air driven by one or more impellers, which can be located within or without the apparatus, upstream or downstream of the target.

Abstract: Disclosed is a toner recycle device for supplying recovered toner into a developing device again and reusing it. The ratio of the amount of the recovered toner to be supplied into the developing device to the amount of new toner is arbitrarily increased or reduced. Further, as the remaining amount of the new toner reduces, one or a plurality of the following three processing steps of a toner save mode are executed: (1) to increase the ratio of the amount of the recovered toner, which is supplied into the developing device, to the amount of the new toner; (2) to reduce the total amount of the recovered toner and the new toner to be supplied; and (3) to stop the new toner to be supplied into the developing device and to supply only the recovered toner. Furthermore, an ordinary mode and the toner save mode are automatically switched or arbitrarily switched manually.

Abstract: An apparatus for developing a latent image recorded on a movable imaging surface, including: a reservoir for storing a supply of developer material including toner particles, the reservoir including a developer material mixing and transport area; a donor member being arranged to receive toner particles from the reservoir and to deliver toner particles to the image surface at locations spaced apart from each other in the direction of movement of the imaging surface thereby to develop the latent image thereon; and a climate system, associated with the reservoir, for maintaining the supply of developer material at a predefined temperature, the climate system includes a cooling element for supplying cool air to the developer material mixing and transport area, and a heating element positioned within air path for heating air to predefined temperature.

Abstract: A recovered toner classifier includes a rotatable cylindrical-shaped filter and a fur brush having a brush spirally provided on an outer peripheral surface of a rotation shaft. A non-brush region is continuously formed from the inlet of the filter for the recovered toner through the outlet of the filter for discharging the disposal toner along the axis line of the rotation shaft. The fur brush integrally rotates with the rotation shaft with a tip portion of the brush is in press-contact with an inner peripheral surface of the filter. A screw conveyer having a screw on a portion of the rotation shaft on a side of the inlet of the filter for the recovered toner is provided to convey the recovered toner to the inlet of the filter for the recovered toner.

Abstract: An apparatus for developing a latent image recorded on a movable imaging surface, including: a reservoir for storing a supply of developer material including toner particles, said reservoir including a developer material mixing and transport area; a donor member being arranged to receive toner particles from said reservoir and to deliver toner particles to the image surface at locations spaced apart from each other in the direction of movement of the imaging surface thereby to develop the latent image thereon; and a climate system, associated with said reservoir, for maintaining said supply of developer material at a predefined temperature, said climate system includes a cooling element for supplying air to said developer material mixing and transport area, and a heating element positioned in said developer material mixing and transport area, said heating element includes a first heat unit associated with heating an inboard area of said developer material mixing and transport area and a second heat unit assoc

Abstract: A recovered toner classifier includes a rotatable cylindrical-shaped filter and a fur brush having a brush spirally provided on an outer peripheral surface of a rotation shaft. A non-brush region is continuously formed from the inlet of the filter for the recovered toner through the outlet of the filter for discharging the disposal toner along the axis line of the rotation shaft. The fur brush integrally rotates with the rotation shaft with a tip portion of the brush is in press-contact with an inner peripheral surface of the filter. A screw conveyer having a screw on a portion of the rotation shaft on a side of the inlet of the filter for the recovered toner is provided to convey the recovered toner to the inlet of the filter for the recovered toner.

Abstract: A recovered toner classifier includes a rotatable cylindrical-shaped filter and a fur brush having a brush spirally provided on an outer peripheral surface of a rotation shaft. A non-brush region is continuously formed from the inlet of the filter for the recovered toner through the outlet of the filter for discharging the disposal toner along the axis line of the rotation shaft. The fur brush integrally rotates with the rotation shaft with a tip portion of the brush is in press-contact with an inner peripheral surface of the filter. A screw conveyer having a screw on a portion of the rotation shaft on a side of the inlet of the filter for the recovered toner is provided to convey the recovered toner to the inlet of the filter for the recovered toner.

Abstract: In accordance with the present invention, in an image forming apparatus of the type developing a latent image formed on an image carrier, which moves at a linear velocity of 400 mm/sec or above, with a developer containing toner grains having a volume mean grain size of 5 &mgr;m to 10 &mgr;m and 60 number percent to 80 number percent of which has a grain size of 5 &mgr;m or below, the developer contains carrier grains having a weight mean grain size of 65 &mgr;m or below. When use is made of toner with a small grain size, the apparatus successfully obviates background contamination, toner scattering and sleeve contamination without regard to operation speed or environmental conditions.

Abstract: An electrophotographic printing machine, wherein an electrostatic latent image recorded on a photoconductive member is developed to form a visible image thereof, the electrophotographic printing machine including a system, for removing contaminants from toner in a developer housing, the system including a filter system, positioned in a path of flowing developer material, the filter system having a screen for permitting developer material to travel therethrough while inhibiting contaminants from traveling therethrough when vibrated; the screen being inclined to the path of flowing developer material a vibration driver, operatively connected to the screen, for vibrating the screen.

Abstract: A powder classifying device that classifies powder includes a mesh member having meshes, and a brush roller formed with hair-like members and configured to rotate in sliding contact with the mesh member at a predetermined portion in a circumferential direction of the brush roller to push the powder conveyed in a radial direction of the brush roller against the meshes so that the powder is classified into powder passing through the meshes and powder not passing through the meshes.

Abstract: A developing device includes a developing roller and a toner charging roller. The toner charging roller has (a) a metallic layer which induces its electrons by receiving light irradiation, and (b) an ultraviolet irradiater which irradiates ultraviolet to the metallic layer. The toner charging roller gives the electrons to toner, so that the toner on the developing roller is charged. There is a space between the toner charging roller and the developing roller, and a grid electrode which controls a flow of the electrons is provided in the space. Thus, mechanical/thermal load given to the toner or the toner charging roller can be reduced, so that it is possible to prevent deterioration of toner and the device.

Abstract: A toner deliver system, such as a development roller, in an electrophotographic printer is conditioned with clear toner particles. The clear toner particles are made of similar resins and contains all of the flow and charge agents of color toner particles, but does not contain any pigment.

Abstract: An electrophotographic printing machine, wherein an electrostatic latent image recorded on a photoconductive member is developed to form a visible image thereof, the electrophotographic printing machine including a system, for removing contaminants from toner in a developer housing, the system including a filter system, positioned in a path of flowing developer material, the filter system having a screen for permitting developer material to travel therethrough while inhibiting contaminants from traveling therethrough when vibrated; the screen being inclined to the path of flowing developer material a vibration driver, operatively connected to the screen, for vibrating the screen.

Abstract: A method and apparatus for electrophotographic image forming are provided incorporating an improved toner recycling unit. This recycling unit is devised such that the selectable switching between toner recycling and non-recycling modes be continually carried out according to the decision based on the present amount of paper dusts measured by a paper dust measuring unit provided in a paper dust removal unit. The image forming apparatus incorporating the toner recycling unit is therefore capable of efficiently recycling the toner recovered from a cleaning unit without removing contaminants such as paper dusts and toner aggregates included in the recycled toner, thereby preventing the emergence of undesirable picture image anomalies such as whisker images and black dots.

Abstract: An apparatus and method for dispensing toner in an electrostatographic printer includes apparatus for agitating toner contained by a relatively large toner container (e.g., 10-25 liters in volume). The apparatus includes a substantially vertically-oriented shaft supporting a blade that operates, as the blade rotates, to drive the contained toner mass upwardly, thereby aerating the mass and preventing compaction during toner dispensing.

Abstract: An apparatus and method for dispensing toner in an electrostatographic printer includes apparatus for drawing ambient air in a vertical direction, preferably upwards, through a relatively large toner container. The air-flow is sufficient to fluidize the toner in the toner container and thereby prevent compaction. Such fluidization is optionally supplemented by the action of an auger or propeller mechanism mounted within the toner container. During rotation of the auger/propeller, the toner is lifted and thereby further prevents toner compaction.

Abstract: In accordance with the present invention, in an image forming apparatus of the type developing a latent image formed on an image carrier, which moves at a linear velocity of 400 mm/sec or above, with a developer containing toner grains having a volume mean grain size of 5 &mgr;m to 10 &mgr;m and 60 number percent to 80 number percent of which has a grain size of 5 &mgr;m or below, the developer contains carrier grains having a weight mean grain size of 65 &mgr;m or below. When use is made of toner with a small grain size, the apparatus successfully obviates background contamination, toner scattering and sleeve contamination without regard to operation speed or environmental conditions.

Abstract: A developing apparatus prevents a reduction in image density due to paper powder by providing a developing apparatus that has a developing container, a toner carrying member, and a toner container, wherein the toner container has a space portion, which is disposed below the toner carrying member and which is not substantially replenished with the toner.

Abstract: A rotation molded particulate collection bottle for a copier/duplicator machine, which is connectable to a particulates separation source, which is not prone to failure under vacuums required in the air circulation systems for copier/duplicator machines and which is rotation molded and has a wall thickness of at least about 0.20 inches.

Abstract: A recovered toner classifier includes a rotatable cylindrical-shaped filter and a fur brush having a brush spirally provided on an outer peripheral surface of a rotation shaft. A non-brush region is continuously formed from the inlet of the filter for the recovered toner through the outlet of the filter for discharging the disposal toner along the axis line of the rotation shaft. The fur brush integrally rotates with the rotation shaft with a tip portion of the brush is in press-contact with an inner peripheral surface of the filter. A screw conveyer having a screw on a portion of the rotation shaft on a side of the inlet of the filter for the recovered toner is provided to convey the recovered toner to the inlet of the filter for the recovered toner.

Abstract: An improvement for use in a fine particle delivery system that separates particulate material according to particle size, such as a toner screener used in an electrophotographic imaging machine. The fine particle delivery system includes an intake duct that receives particulate material, a screen that filters the materials as the particles move or rotate about the screen, and a pair of opposed ultrasonic transducer assemblies that excite the screen to dislodge particulate material adhering to the screen mesh. Each transducer assembly includes a transducer, a rigid metallic membrane coupled to transducer to efficiently deliver ultrasonic waves to the screen, and a mounting mechanism that supports the transducer assembly. A channel embedded with the mounting mechanism protects electrical wiring the powers the transducer from a potentially explosive environment of particulate material during screening operations.

Abstract: In image forming apparatuses producing recycled toner from residual toner and recycling the recycled toner, the toner composition changes, and the toner properties worsen, because the external additive contained in the collected residual toner that is collected with a cleaning portion decreases during the image formation. The residual toner that has been collected with the cleaning portion is conveyed through a conveyance path to a collected residual toner storage, and external additive is supplemented from an external additive cartridge, and mixed with being stirred to produce recycled toner. In a fresh toner storage, fresh toner and recycled toner are stirred, and when the amount of toner in a developing portion drops below a predetermined amount, toner is conveyed from the fresh toner storage through a conveyance path to the developing portion. The toner that has been conveyed to the developing portion is supplied to a photosensitive drum.

Abstract: A powder classifying device that classifies powder includes a mesh member having meshes, and a brush roller formed with hair-like members and configured to rotate in sliding contact with the mesh member at a predetermined portion in a circumferential direction of the brush roller to push the powder conveyed in a radial direction of the brush roller against the meshes so that the powder is classified into powder passing through the meshes and powder not passing through the meshes.

Abstract: An improvement for use in a fine particle delivery system that separates particulate material according to particle size, such as a toner screener used in an electrophotographic imaging machine. The fine particle delivery system includes an intake duct that receives particulate material, a screen that filters the materials as the particles move or rotate about the screen, and a pair of opposed ultrasonic transducer assemblies that excite the screen to dislodge particulate material adhering to the screen mesh. Each transducer assembly includes a transducer, a rigid metallic membrane coupled to transducer to efficiently deliver ultrasonic waves to the screen, and a mounting mechanism that supports the transducer assembly. A channel embedded with the mounting mechanism protects electrical wiring the powers the transducer from a potentially explosive environment of particulate material during screening operations.

Abstract: An electrophotographic apparatus which forms an electrostatic latent image on a photoreceptor includes a developing device configured to accommodate a two-component developer including toner and carrier and to develop the electrostatic latent image with the developer. Toner which has been used for developing the electrostatic latent image is recycled to the developing device so as to be used again. The developing device includes a developer conveying path so as to convey the recycled toner therethrough. A screening member having openings to screen the recycled toner is arranged in the developer conveying path.

Abstract: It is an object of the invention that development quality is improved by increasing the amount of charge during the transportation of toner by a toner holding member and decreasing the amount of charge during development for rendering an electrostatic latent image visible. A one-component non-magnetic toner is supplied from a toner supplying unit to the toner holding member such that the toner is electrostatically attracted to adhere to the toner holding member with a large amount of charge. The charge of the toner under transportation is reduced by charge adjusting means such as a conductive roller supplied with a potential from a frictional charging member or a voltage source, whereby the amount of development or the amount of toner adhering to an electrostatic latent image is increased and development quality is improved.

Abstract: In image forming, the ratio of foreign substances mixed in the recycled toner which is removed from the photoreceptor drum surface by means of the cleaning device is computed as one of the characteristics of the recycled toner, based on the paper size, the image area and the transfer efficiency. If the recycled toner has a high ratio of foreign substances mixed therein and is determined to have a low quality, collection of the recycled toner into the developing unit is temporarily interrupted and a fixed amount of toner is conveyed from the developing unit to the cleaning device so as to improve the quality of the recycled toner. In this way, recycled toner of a low quality is prohibited from being used for subsequent image forming operations so as to prevent degradation of the image quality.

Abstract: An apparatus which develops an electrostatic latent image recorded on a photoconductive member used in an electrophotographic printing machine. The apparatus employs a development material wherein developability degradates as the duration of time that the toner particles remain in the developer housing increases. Developability is significantly improved by periodically adding a flow additive material to the developer material.

Abstract: An image forming apparatus including a plurality of filters for obtaining reusable toner from used toner scraped off of an image carrier. Also included is a reusable toner container for storing the reusable toner, and a toner transfer device for transferring the reusable toner stored in the reusable toner container to a developing device so that the reusable toner is reused by the developing device. The plurality of filters have a different mesh-size and are positioned in a used toner stream in an order based on the different mesh-size.

Abstract: An image forming apparatus includes an image bearing member, a latent image forming device that forms a latent image on the image bearing member, a developing device that develops latent image on said image bearing member to a toner image with a two-component developer, and a toner density detecting device that detects toner density of the two-component developer in which the toner image is formed and outputted as a visible image onto a transfer member. A control device is provided for agitating the developer for a predetermined time period during an initial setting is performed for the developer, detecting a toner density of said developer after the predetermined agitation, and performing an abnormal process when a result of the detection is out of the predetermined range.