Abstract: A developing device includes a storage portion storing a developer, a conveying portion stirring and conveying the developer in the storage portion, a sensor, an acquisition processing portion, and a correction processing portion. The sensor outputs an electrical signal in accordance with magnetic permeability at a predetermined detection position in a conveyance path of the developer. The acquisition processing portion acquires a specific value based on the electrical signal outputted during a rotation period of the conveying portion. The correction processing portion corrects the specific value based on a rotation speed of the conveying portion when a fluctuation width of the electrical signal outputted during the rotation period of the conveying portion is less than a predetermined threshold, and corrects the specific value based on the rotation speed of the conveying portion and the fluctuation width when the fluctuation width is equal to or greater than the threshold.

Abstract: An image forming apparatus is operable in a first small-sheet printing in which power is supplied to the first heat generating element and the second heat generating element and in a second small-sheet printing in which power is supplied to the first heat generating element and the third heat generating element. A first power ratio, which is a proportion of power supplied to the first heat generating element to power supplied to the second heat generating element in the first small-sheet printing, is higher than a second power ratio, which is a proportion of power supplied to the first heat generating element to power supplied to the third heat generating element in the second small-sheet printing.

Abstract: An image forming apparatus includes an image bearing member, a transfer member, a cleaning member, and an executing portion configured to execute a supplying operation for forming a predetermined toner image on the image bearing member during non-image formation and then supplying toner of the predetermined toner image to the contact portion. The executing portion executes the supplying operation with a forming condition of the predetermined toner image preset on the basis of information preset on contact pressure applied by the cleaning member to the image bearing member.

Abstract: A toner conveying member is a member with a shaft and a screw around a longitudinal non-end portion (i.e., a central portion) of the shaft integrally molded with resin, and also includes a metal pipe. The metal pipe includes a surrounding portion provided around an end portion of the shaft where the screw is not provided, and a buried portion buried in at least a portion of the screw and extended from the surrounding portion.

Abstract: A controller controls a replenishing operation of the first replenishing device based on the first sensor, and controls a replenishing operation of the second replenishing device based on the second sensor. The controller prohibits the replenishing operation of the first replenishing device when the developer concentration in the first replenishing device reaches a first upper limit set to the first developing device, and the controller prohibits the replenishing operation of the second replenishing device when the developer concentration in the second replenishing device reaches a second upper limit set to the second developing device. The controller corrects the second upper limit based on the developer concentration in the second developing device when the developer concentration in the first developing device reaches the first upper limit.

Abstract: In an image forming apparatus, the magnetic sensor obtains an output value varying with a magnetic toner amount in a development device. The correlative data storing part prestores correlative data relating to the output value when there is no magnetic toner in the development device and the output value when the magnetic toner amount is a predetermined setting value. The standard value storing part prestores an initial value of a standard value being the output value when the magnetic toner amount is the setting value. The standard value setting part makes the standard value storing part store the output value corresponding to the magnetic toner amount being the setting value, as new standard value, by the output value when there is no magnetic toner in the development device and the correlative data. The toner amount deciding part decides the magnetic toner amount by the output value and the standard value.

Abstract: An image forming apparatus includes: a first image forming unit configured to form an image on a sheet using a first colorant to be heat-fixed on the sheet; a second image forming unit configured to form an image on the sheet using a second colorant that is erasable by heating; and a fixing device arranged further on a downstream side in a sheet conveying direction than the first image forming unit and further on an upstream side in the sheet conveying direction than the second image forming unit and capable of executing fixing processing for heat-fixing the image, which is formed on the sheet by the first image forming unit, on the sheet and executing erasing processing for heating the sheet, on which the image is formed with the second colorant, to erasing temperature to thereby erase the second colorant on the sheet.

Abstract: A developing unit includes a developer storage unit, a developer bearing member, an agitation member, a flexible member, and a magnet member. The developer storage unit stores a developer. The developer bearing member develops an electrostatic latent image formed on an image bearing member with the developer. The agitation member agitates the developer in the developer storage unit. The flexible member, disposed in the developer storage unit, is distorted by pressure applied by the agitation member via the developer. The magnet member, disposed on the flexible member, is displaced in response to the flexible member being distorted.

Abstract: An image forming device includes a toner supplying unit to supply the toner to a storage unit. A mixer supplies developer in the storage unit to a developing roller, and a developer sensor detects the amount of developer on the surface of the developing roller. A toner concentration sensor detects toner concentration in the developer stored in the storage unit, and a control unit adjusts at least one of a developing bias and a rotation speed of the mixer based on a value detected by the developer sensor and a value detected by the toner concentration sensor, such that a printed image has uniform density.

Abstract: In an image forming apparatus, the magnetic sensor obtains an output value varying with a magnetic toner amount in a development device. The correlative data storing part prestores correlative data relating to the output value when there is no magnetic toner in the development device and the output value when the magnetic toner amount is a predetermined setting value. The standard value storing part prestores an initial value of a standard value being the output value when the magnetic toner amount is the setting value. The standard value setting part makes the standard value storing part store the output value corresponding to the magnetic toner amount being the setting value, as new standard value, by the output value when there is no magnetic toner in the development device and the correlative data. The toner amount deciding part decides the magnetic toner amount by the output value and the standard value.

Abstract: There are provided a powder supply element adapted to supply powders containing at least toner; developing element adapted to develop an electrostatic latent image by agitating and conveying a developer containing the powders that are supplied by the powder supply element; a toner amount detecting element that is placed in the middle of a conveyance path to connect the powder supply element with the developing element and detects a toner amount per unit volume to be supplied to the developing element; and control element that controls a correction amount with respect to a reference supply amount due to the powder supply element on the basis of a toner amount per unit volume that is detected by the toner amount detecting element.

Abstract: An image forming apparatus includes: a first image forming unit configured to form an image on a sheet using a first colorant to be heat-fixed on the sheet; a second image forming unit configured to form an image on the sheet using a second colorant that is erasable by heating; and a fixing device arranged further on a downstream side in a sheet conveying direction than the first image forming unit and further on an upstream side in the sheet conveying direction than the second image forming unit and capable of executing fixing processing for heat-fixing the image, which is formed on the sheet by the first image forming unit, on the sheet and executing erasing processing for heating the sheet, on which the image is formed with the second colorant, to erasing temperature to thereby erase the second colorant on the sheet.

Abstract: An image forming apparatus includes: an image carrier; an image-forming device including a toner and forming a toner image on the image carrier during a first running period; a detector detecting a toner quantity in a set period within the first running period; and a toner supplying device supplying the image-forming device with a toner according to the detected toner quantity. The apparatus further includes a period setting device that causes the image-forming device to stir the toner over a second running duration longer than the first running duration, and causes, during the second running duration, the detector to perform detection plural times over a period longer than the period, thereby measuring a result stable time required to stabilize the result of the detection, and setting in the detector, as the period, a period over which the result of the detection is stable within the first running duration.

Abstract: The developer supplying device supplies a supplementary developer including a toner and a carrier in a predetermined weight ratio. The developer supplying device includes a supplementary developer container containing the supplementary developer, and a supplementary developer feeding passage configured to feed the supplementary developer from the supplementary developer container to a developing device. The supplementary developer container is replaced when the supplementary developer is substantially exhausted. The developer supplying device further includes a carrier concentration determining device provided on the supplementary developer feeding passage to determine the concentration of the carrier in the supplementary developer fed through the supplementary developer feeding passage, and a residual supplementary developer amount estimating device configured to estimate the amount of the supplementary developer remaining in the supplementary developer container.

Abstract: An image forming apparatus includes: a first image forming unit configured to form an image on a sheet using a first colorant to be heat-fixed on the sheet; a second image forming unit configured to form an image on the sheet using a second colorant that is erasable by heating; and a fixing device arranged further on a downstream side in a sheet conveying direction than the first image forming unit and further on an upstream side in the sheet conveying direction than the second image forming unit and capable of executing fixing processing for heat-fixing the image, which is formed on the sheet by the first image forming unit, on the sheet and executing erasing processing for heating the sheet, on which the image is formed with the second colorant, to erasing temperature to thereby erase the second colorant on the sheet.

Abstract: In this toner concentration sensor, as the magnetic permeability of a two-component developer 3 containing toner and carrier in a two-component developing unit 1 has changed with changing TC ratio of the two-component developer, the oscillation frequency of a first oscillation circuit 20 having a detection coil 5 changes, on the other hand the oscillation frequency of a second oscillation circuit 30 having a reference coil 6 does not change. While, changes in temperature conditions cause the oscillation frequency of the second oscillation circuit to change in the same way as the oscillation frequency of the first oscillation circuit. Therefore, utilizing a difference between the oscillation frequencies of the first and second oscillation circuits makes it possible to cancel out changes in the temperature conditions so that a value corresponding to only the magnetic permeability of the two-component developer can be obtained.

Abstract: A magnetic material detecting device, in which a concentration of magnetic material can be correctly detected, even when the magnetic material with unevenness in its density distribution flows. A magnetic field generating device is arranged in a two-component developer composed of magnetic carrier and non-magnetic toner and generates a magnetic field. A signal output device is arranged in the developer and outputs a signal depending on a magnetic permeability of the developer due to the magnetic field generated by the magnetic field generating device. An agitating unit agitates the developer and makes the developer flow between the magnetic field generating device and the signal output device. A detecting unit detects a proportion of the toner in the developer based on a result of multiple times sampling of the signal outputted from the signal output device after the agitating unit starts to operate.

Abstract: An image forming apparatus includes an optical sensor configured to optically detect a density of a reference pattern image, a toner density sensor configured to detect a density of toner in a developing unit, a storing unit configured to store an image area coverage of an output image, a determining unit configured to determine whether a state of toner accommodated in a toner supplying unit is an almost empty state and an empty state or neither based on detection results obtained by the sensors, a controlling unit configured to continuously perform a toner state check when the image area coverage of the output image is greater than a predetermined image area coverage value and the density of the reference pattern image is greater than a predetermined density level after the determination of the state of toner is the almost empty state or the empty state or neither.

Abstract: An image forming apparatus in which a predetermined image density can be obtained by correcting a toner density control target value without consuming toner. The toner density of the developer is controlled so that an output value Vt of a magnetic permeability sensor approaches a target output value Vtref. In addition, the target output value Vtref is corrected in accordance with image coverage history information of output images transferred to a transfer paper and image coverage ratio history information of output images determined from the image coverage thereof and the size of the transfer paper. This history information comprises, for example, a cumulative average value of the image coverage or the image coverage ratio per transfer paper. It may also comprise a moving average value of the image coverage or the image coverage ratio per transfer material.

Abstract: An image forming apparatus including an exposure device, a development device, an image density detection device, a supply device for supplying a toner to the development device, a cleaning device for cleaning the surface of an image bearing member, a driving torque detection device for detecting a driving torque of the image bearing member, and a controller which drives the image bearing member while providing a predetermined electric potential difference between a region charged in the image bearing member and a developer support in case of non-image formation conducts a driving torque detecting operation with respect to the image bearing member by means of the driving torque detection device, and changes a reference value in response to the value of the driving torque detected.

Abstract: A plurality of chambers are adapted to accommodate a plurality of cartridges each containing toner to be used for printing. A mode changer is operable to change an operation mode of the printing apparatus in accordance with a combination of respective colors of toner in the cartridges accommodated in the chambers. A first detector is operable to detect a residual amount of toner in each of the cartridges. A second detector is operable to detect the respective colors of toner in the cartridges when the operation mode is changed. A controller is operable to generate an image data including a plurality of first identifiers each indicative of the residual amount of toner in one of the cartridges and a plurality of second identifiers each indicative of one of the colors of toner and associated with one of the first identifiers. A display is adapted to display the image data.

Abstract: A magnetic material detecting device, in which a concentration of magnetic material can be correctly detected, even when the magnetic material with unevenness in its density distribution flows. A magnetic field generating device is arranged in a two-component developer composed of magnetic carrier and non-magnetic toner and generates a magnetic field. A signal output device is arranged in the developer and outputs a signal depending on a magnetic permeability of the developer due to the magnetic field generated by the magnetic field generating device. An agitating unit agitates the developer and makes the developer flow between the magnetic field generating device and the signal output device. A detecting unit detects a proportion of the toner in the developer based on a result of multiple times sampling of the signal outputted from the signal output device after the agitating unit starts to operate.

Abstract: An object of the present invention is to provide a remaining amount of toner detecting apparatus capable of highly accurately detecting the remaining amount of toner with a simple configuration, a toner cartridge in which the remaining amount of toner is highly accurately detected with a simple configuration, and an image forming apparatus which enables the operator to easily recognize time to resupply toner and is capable of forming an image of high image quality. A holding member (22) is flexible, one end (22a) in the longitudinal direction is connected to a stirring member (11), and the other end (22b) in the longitudinal direction holds a detection auxiliary member (21) disposed in a housing (8). Consequently, the holding member (22) and the detection auxiliary member (21) rotate as the stirring member (11) rotates.

Abstract: A controller determines the degree of acuteness of the resonant oscillation of a piezoelectric oscillator, based on the developer's fluidity detection data detected by the piezoelectric oscillator. The toner density output data detected by a toner density sensor is modified to a correct value, based on the degree of acuteness, and a supply roller is controlled based on this corrected value so as to implement the necessary toner supply.

Abstract: In an image forming apparatus having a toner recycle mechanism employing a two-components developing system, rotational torque of a stirring screw disposed within a developing device and capacity of a recycle toner within the developing device are detected. Where the rotational torque of stirring screw is elevated and the capacity of the recycle toner is increased, control operation for not changing a development bias voltage and lowering rotational speed of the stirring screw is executed. Where the rotational torque of the stirring screw is elevated and the capacity of the recycle toner is not increased, control operation for not changing rotational speed of the stirring screw is executed.

Abstract: An image forming apparatus includes an image bearing member on which a latent image corresponding to image information is formed, a developing device for developing the latent image on said image bearing member with a developer including carrier and toner, a supplying device for supplying a developer to the developing device, a detector for detecting information corresponding to the magnetic permeability of the developer, and a selecting device for selecting modes on the basis of the information detected by the detecting device, wherein the selecting device can select a first control mode that controls the amount of the developer which is supplied to the developing device by the supplying device on the basis of the information detected by the detector, and a second control mode that controls the amount of the developer which is supplied to the developing device by the supplying device on the basis of the image information.

Abstract: A developing device for developing a latent image formed on an image carrier with a developing liquid includes a liquid storing section for storing the liquid including a developing substance and a carrier liquid. A developer carrier deposits the liquid fed from the liquid storing section thereon. A float type liquid level sensor senses a liquid level in the liquid storing section. The liquid level sensor includes a magnetic force generating member for generating a magnetic force, a magnetic force sensing device for sensing the magnetic force, and floats movable up and down in accordance with the liquid level in the liquid storing section. A distance between the magnetic force generating member and the magnetic force sensing device varies in accordance with the movement of the floats, allowing the liquid level to be determined on the basis of the output of the magnetic force sensing device.

Abstract: A developing device includes a developer including toner having a coloring agent dispersed in a binder resin, and carrier having a core material, and a coating layer covering the core material and containing a binder resin and a powder. A toner density detecting device detects a toner density of the developer by use of a bulk density sensor, and a control device controls the toner density based on a detection result of the toner density detecting device. The toner density is controlled such that ratio (D/h) of an average particle diameter (D) of the powder to a thickness of the coating layer is greater than 1 and less than 10.

Abstract: This invention relates to an image forming apparatus including a developing unit which develops an electrostatic latent image formed on an image carrier by using a two-component developing agent containing polymerized toner. The developing unit includes a supply/convey member which conveys the two-component developing agent in the axial direction while agitating it and a toner density sensor which detects the toner density of the two-component developing agent. The toner density sensor is placed to be in a non-contact state with respect to the supply/convey member and oppose it with a gap of 0.8 mm or less. The diameter of the supply/convey member is set to 23 mm or more.

Abstract: An image forming apparatus in which the control of toner supply can be effected well irrespective of an image forming mode (image forming speed). The density of a toner in a developer contained in a developer containing portion is detected by a toner density sensor. A controller controls the supply of the toner to the developer containing portion so that the density of the toner detected by the toner density sensor may assume a predetermined target value. When the last developing operation is executed at an ordinary speed, whereafter next developing operation is executed at a low speed, a toner image of predetermined density is formed, and the density of this toner image is detected by an image density sensor. The controller determines an amount of toner supply by the use of the target value corrected on the basis of the detection output of the image density sensor, and the detection output of the toner density sensor.

Abstract: A process cartridge which is detachably mountable to a main body of an image-forming apparatus has a photosensitive member, a magnetic toner-holding section provided with a magnetic toner-carrying member which transports the toner to a developing zone, and a residual magnetic toner detector capable of detecting residual toner by a change in electrostatic capacity which is caused between electrodes provided inside the magnetic toner-holding section. The magnetic toner contains at least a binder resin and a colorant, having a weight-average particle diameter of from 6.5 &mgr;m to 15.0 &mgr;m, and having a Carr's floodability index of more than 80.

Abstract: A developing device of the present invention includes a conveying member for conveying a developer that is a toner and carrier mixture. A sensor senses the toner content of the developer in terms of the permeability of the developer. A preventing member prevents the bulk density of the developer from varying when fresh toner is not replenished. The developing device obviates erroneous toner content sensing when fresh toner is not replenished. An image forming apparatus including the developing device is also disclosed.

Abstract: A permeability detection apparatus configured to stably execute a permeability detection operation for toner concentration and characterized by improved sensitivity. The permeability detection apparatus includes: a detection circuit 22; an oscillation circuit 21 that oscillates a natural frequency to drive the detection circuit; and a phase comparison circuit 23 that extracts signals at an input side of the detection circuit and an end side of the circuit element to perform phase comparison. The detection circuit 22 includes a coil L1, a capacitor C1 connected to the coil in series or in parallel, and a resistance R1 connected to the coil in series or in parallel, and a resistance R1 connected to the coil and the capacitor. The resistance R1 allows the oscillation circuit to eliminate influence from the detection circuit and to oscillate the natural frequency continuously. The coil and the capacitor form a resonant circuit, and a resonant frequency circuit is set approximately equal to the natural frequency.

Abstract: In a detection unit, a measurement electrode member is arranged at a position where it contacts a developer, and has an input electrode for receiving a voltage from an apparatus main body and an output electrode for outputting an electrical signal in accordance with an electrostatic capacitance generated upon application of the voltage. A reference electrode member is arranged at a position where it does not contact the developer, and has an input electrode for receiving a voltage from the apparatus main body and an output electrode for outputting an electrical signal in accordance with an electrostatic capacitance generated upon application of the voltage. The measurement electrode member is adhered to an adhesion member. A lid member is coupled to the adhesion member and covers the reference electrode member. An engaging portion engages with a vessel positioning portion attached to the developer vessel, and positions the detection unit with respect to the developer vessel.

Abstract: Toner (5) is measured in a toner cartridge (1) by compressing the air in the upper part (7) of the toner hopper (3). The result of the compression is observed by a diaphragm (13) or, alternatively, by a pressure transducer (25). The volume of air is inversely proportional to the resonant frequency of diaphragm (13) or the pressure at pressure transducer (25). This is converted by control system (23) using direct equations or table look-up of empirical data. The diaphragm (13) carries a magnet (15), which is driven by coil (19) from the imaging device and then frequency of current induced by magnet (15) is then sensed by coil (19). Uneven toner piling is not a significant factor in the results measured.

Abstract: A developer container for containing a developer includes a detecting member for detecting a developer amount having an electrode member having a pair of input-side and output-side electrodes formed in parallel and in one plane at a predetermined interval and adapted to detect the capacitance between the electrodes, a measurement-side electrode that is in contact with the developer, and a reference electrode that is out of contact with the developer, the detecting member being provided on a side surface of the developer container. The container also includes a developer removing member for removing developer adhering to a detection surface of the detecting member, the developer removing member being attached to the developer conveying member and in contact with the detection surface of the detecting member so as to remove developer on the detection surface of the detecting member.

Abstract: A developing device of the present invention includes a conveying member for conveying a developer that is a toner and carrier mixture. A sensor senses the toner content of the developer in terms of the permeability of the developer. A preventing member prevents the bulk density of the developer from varying when fresh toner is not replenished. The developing device obviates erroneous toner content sensing when fresh toner is not replenished. An image forming apparatus including the developing device is also disclosed.

Abstract: Disclosed is a permeability detection apparatus that stably executes an operation of permeability detection such as toner concentration, and that improves sensitivity of permeability detection.

Abstract: A developing apparatus includes a developer container for containing a developer comprising magnetic carrier and non-magnetic toner produced through polymerization method; a developer carrying member, provided in an opening of the developer container, for carrying the developer; detecting means for detecting a toner content in the developer, the detecting means including a coil sensor and detecting the toner content using magnetic permeability of the developer.

Abstract: A donor member, useful in ionographic or electrophotographic apparatuses and preferably useful in hybrid scavengeless development units, has a substrate and an oxidized transport coating thereover. The oxidized transport coating includes a polymer binder, charge transporting molecules and one or more oxidizing agents. The polymer binder of the donor roll coating preferably includes one of (1) a crosslinked polymer with charge transporting molecules dispersed therein, or (2) a crosslinked polyamide binder with hydroxy charge transport molecules dispersed therein. The donor roll is preferably included in a printing machine that develops latent images formed on a photoconductive member.

Abstract: The present invention provides a toner concentration control device which can measure the concentration of toner stably in an extended period of time without influenced by the shape of a developer stirring mixer rib and mounting position of a toner concentration detecting censer, with a result the stagnation or adhesion of toner in the proximity of the toner concentration detecting censer is eliminated, by so composing a toner concentration control device having a toner concentration censer for detecting magnetically the concentration of toner mounted facing a developer stirring mixer in a developing vessel, so that a waveform detection means which detects the output of the toner concentration censer for at least over one cycle before a toner supply means is activated, and an about-minimum value judging means which judges the minimum value or its vicinity detected by the waveform detection means are provided, and an about-minimum detection means is activated on the basis of the value judged as minimum or its

Abstract: A method for determining whether or not a developer container to contain developer is attached to the main body of an apparatus comprises the steps of detecting information of the magnetic permeability of developer in the developer container; and determining whether or not the developer container is attached to the main body of the image forming apparatus in accordance with an output (or outputs) obtained in the step of detection. With the adoption of this method comprising these steps, there is no need for providing separately any sensor or the like which is dedicated to determining whether or not the developer container is attached to the main body of the image forming apparatus, hence making it possible to implement reducing the costs of an image forming apparatus, and making the image forming apparatus smaller.

Abstract: A developing device comprises a developer bearing member for bearing and conveying a developer having a toner and a carrier, a first magnetic pole arranged in the developer bearing member, a second magnetic pole arranged in the developer bearing member, a polarity of the second magnetic pole being opposite to a polarity of the first magnetic pole, and the second magnetic pole being adjacent to the first magnetic pole and arranged on a downstream side of the first magnetic pole in a moving direction of the developer bearing member, a regulating member for regulating a layer thickness of the developer borne by the developer bearer, the regulating member being arranged in the vicinity of the second magnetic pole and a concentration detector for detecting a concentration of the toner in the developer.

Abstract: A developing device mounted on a main body of an electrophotographic image forming apparatus and adapted to develop an electrostatic latent image formed on an electrophotographic photosensitive member includes a developer container having a developing portion with a developer bearing member for containing a developer and feeding the developer to the electrophotographic photosensitive member, and a hopper portion for containing the developer and supplying the developer to the developing portion, in order to develop the electrostatic latent image formed on the electrophotographic photosensitive member, and a developer residual amount detecting electrode pair having first and second electrodes disposed to interpose said developing portion and the hopper portion therebetween in order to detect the residual amount of developer by the main body of the electrophotographic image forming apparatus, wherein the developer residual amount detecting electrode pair are shaped such that a space region defined between the fi

Abstract: An apparatus for controlling the density of a developer is described. The apparatus includes a developer container 51 in which a developer is enclosed; a detector 58 for magnetically detecting information about the density of the toner; toner supply for supplying toner in accordance with an output value from the detecting means; waveform forming for reducing an output value from the detecting means by operating mechanical means 56a for periodically raking out the developer existing on a detecting surface of the detecting means 58; and delaying means for inhibiting detection of the density of toner from a predetermined time at which the output value has been reduced to a time at which the output value is restored to a stable output value. The toner supply means can be operated in accordance with a value detected after the delay means has been suspended.

Abstract: A developer detection apparatus includes a detection member for detecting the developer contained in the developer container detachably mountable on a main body of an image forming apparatus. A biasing member biases the detection member to the developer container side. An interlocking mechanism interlocks with open and close operations of the opening and closing cover for attaching the developer container to or detaching the developer container from the main body of the apparatus. In this developer detection apparatus, when the opening and closing cover is in the open state, the detection member is positioned by the interlocking mechanism in a location so not as to be in contact with the developer container against the biasing force of the biasing member, and when the opening and closing cover is in the closed state, the detection member is positioned so as to be in contact with the developer container by the biasing force of the biasing member.

Abstract: A developing device having a developer bearing member for carrying thereon a developer having toner and carrier and conveying the developer to a developing area, an agitating member for agitating the developer, a rotation radius R (m) of the agitating member being 5.0.times.10.sup.-3 (m)<R<8.0.times.10.sup.-3 (m), and a density sensor for detecting a density of the toner in the developer, the density sensor detecting any change in the density of the toner as a change in a magnetic permeability of the developer, wherein when a shortest distance between an outermost surface of the agitating member and a detecting surface of the sensor is defined as Dmin (m) and a half length of the detecting surface of the sensor in a plane perpendicular to a rotary axis of the agitating member is defined as r, 0 (m)<Dmin<1.0.times.10.sup.31 3 (m) and 0.4<r/R<0.75.

Abstract: An image forming apparatus includes an image bearing member and a charging unit having magnetic particles that are contactable with the image bearing member. An electrostatic image forming unit forms an electrostatic image on the charged image bearing member. A developing device develops an electrostatic image on the image bearing member with toner that includes toner and magnetic carrier. A detecting unit detects the toner content of the developer and a toner supply unit supplies the toner into the developing unit when the detected toner content is lower than a predetermined level. A calculating unit calculates the changing rate of the toner content from an output of the detecting unit and a warning unit warns that a changing rate of the toner content is larger than a predetermined level.

Abstract: A toner density controlling apparatus adapted to control toner density by sensing a T/D level in a developer vessel by using a toner sensor performs a toner density controlling operation on the basis of an output of the toner sensor while maintaining an input control voltage to be applied to the toner sensor at a predetermined level in a definite control range where the toner sensor output decreases proportionally to the T/D level in a linear relation. Conversely, in an indefinite control range where the relationship between the toner sensor output and the T/D level is nonlinear, the input control voltage to be applied to the toner sensor is variably controlled so that the toner sensor output can be adjusted to an upper or lower limit level of the definite control range, and the toner density controlling operation is performed on the basis of the input control voltage.

Abstract: A toner dispenser with on-board intelligence. The toner dispenser includes a reservoir of toner material and memory that stores the characteristics and amount of that toner material contained within. A coil resides inside the reservoir to allow the system into which the dispenser is inserted to vibrate the coil. This accomplishes both a churning of the toner, and the back-EMF of the coil can be measured to calculate the amount of toner remaining. The toner dispenser has communications capability that allows it to send the information contained therein to a system processor of the system into which it is inserted.