Abstract: Disclosed herein is a motor driving apparatus including: an actuator for converting electric energy into rotary motion; a monitoring unit for monitoring a state of the actuator; a control unit for generating a control signal based on an output voltage of the monitoring unit; and a driving signal generation unit for generating a driving signal for the actuator based on the control signal. The control unit may determine whether the monitoring unit normally operates, based on an output voltage of the monitoring unit.

Abstract: The present invention provides an image forming apparatus including a moving member configured to support a first process cartridge and move the first process cartridge to a position for forming an image, and a detection unit configured to detect a state of a second process cartridge, in which the moving member holds the detection unit.

Abstract: A reflection sensor includes the following elements. A light emitting unit emits light to an area of an image forming apparatus where first detection images of plural colors used for detecting amounts of their misregistration are formed. A first light restricting member/configuration restricts light emitted from the light emitting unit. A light receiver is disposed in an optical path of regular reflection light, and receives reflected light and outputs a signal representing an amount of received light. A second light restricting member/configuration is disposed in the optical path of the regular reflection light and restricts light to be received by the light receiver. The value obtained by dividing a diameter of the first light restricting member/configuration by that of the second light restricting member/configuration ranges from substantially 0.5 to 1.9, and the diameters of the first and second light restricting members/configurations are each 1.5 mm or smaller.

Abstract: An image forming apparatus includes an image forming unit configured to form a measurement image on a recording sheet by using a color material, a fixing unit configured to fix the measurement image onto the recording sheet by heating the measurement image, a measurement unit configured to measure color values of the measurement image fixed on the recording sheet downstream of the fixing unit in a sheet conveyance direction of the recording sheet, a pressing member configured to press the recording sheet, on which the measurement image is formed, against the measurement unit, a selection unit configured to select a mode from among a first mode, in which the measurement image is measured with the pressing member pressing the recording sheet against the measurement unit, and a second mode, in which the measurement image is measured without the pressing member pressing the recording sheet against the measurement unit.

Abstract: A toner density sensor comprising: a light emitting element that emits light; a light receiving element that receives reflected light emitted from the light emitting part and reflected at a detection target; a light path for passage of emitted and reflected light formed along the front surface of a printed substrate on which the light emitting element and the light receiving element are surface-mounted; and a diaphragm unit that is formed at and partially narrows this light path, wherein the diaphragm unit is divided into two portions, a diaphragm unit upper-portion and a diaphragm unit lower-portion, and these are disposed in an upper case covering the front surface of the printed substrate and in a lower case covering the rear surface of the printed substrate. In the printed substrate, a through hole is formed for protrusion of the diaphragm unit lower portion from the rear surface to the front surface.

Abstract: An image forming device includes a replaceable cartridge, a light-emitting element, a light-receiving element, and a determining unit. The replaceable cartridge accommodates developer therein and includes an agitator and a developing roller rotatable together with the agitator. The light-emitting element is configured to emit a light toward the replaceable cartridge. The light-receiving element is configured to receive the light emitted by the light-emitting element through the replaceable cartridge to output a signal. The determination value is produced based on the signal. The determining unit is configured to determine whether or not the determination value is greater than a predetermined determination threshold upon the agitator having rotated continuously more than a first prescribed number of times. The determining unit determines that the replaceable cartridge should be replaced with a new one when the determination value is greater than the predetermined determination threshold.

Abstract: An image forming apparatus includes an image bearing member for bearing a latent image, a developer carrying member for developing the latent image with a developer, a developer accommodating portion for accommodating the developer, and a detecting device including a light emitting element and a light receiving element for detecting a remaining developer amount in the developer accommodating portion. In addition, a stirring member stirs the developer by rotating in the developer accommodating portion. The stirring member is rotated in a first period in which the stirring member crosses an optical path of light from the light emitting element toward the light receiving element and a second period in which the stirring member does not cross the optical path of the light.

Abstract: An image forming apparatus is provided that includes an image forming unit including an agitation unit for agitating developing agent contained in a container unit, and a sensor which includes a light emitting unit configured to emit light and a light receiving unit configured to receive the light emitted from the light emitting unit and passing through the container unit. The sensor generates an output in accordance with an amount of light received by the light receiving unit while the agitation unit agitates the developing agent. The image forming apparatus also includes has a medium with instructions stored therein that when executed perform steps including calculating a measurement result based on the output generated by the sensor, and determining, after the agitation is started, whether a current period is an unstable period in which the measurement result is unstable or a stable period in which the measurement result is stable.

Abstract: An image forming apparatus includes a detachably-mounted cartridge including a developer accommodating portion for accommodating a developer and an operation member, a remaining amount detector for detecting a remaining amount of developer in the developer accommodating portion, an operation amount detector for detecting a cumulative operation amount of the operation member, and a setting device for setting timing of subsequent remaining amount detection of the remaining amount detector. The remaining amount detector provides a remaining amount ratio of the developer remainder to a maximum accommodation capacity of the developer accommodating portion, and the operation amount detector provides an operation amount ratio of a remaining operation amount until the end of the service life from the detection of the cumulative operation amount to a total operation amount until the end of the service life from an initial state of the operation member.

Abstract: A detecting apparatus is to at least assist in determining the concentration of colorants within a carrier liquid. The colorants at least absorb light and/or diverge light. The detecting apparatus includes one or more light sources to emit light, and one or more light detectors to detect light. The light sources and the light detectors are positionally configured in relation to one another such that both light directly emitted by the light sources and that has not been absorbed or diverged by the colorants, as well as light diverged by the colorants within the carrier liquid, are detected and/or determined. The concentration of colorants is determined based on the light directly emitted by the light sources that has not been absorbed or diverged by the colorants and/or on the light diverged by the colorants within the carrier liquid.

Abstract: An image forming device includes a density detector that detects image density, and a memory that stores information relating image density to dot size. When a dot size is specified, the image forming device automatically obtains the corresponding image density from the information in the memory, prints a test pattern, compares its density with the density corresponding to the specified dot size, and adjusts an image forming parameter until the density corresponding to the specified dot size is obtained. Dot size can be accurately adjusted in this way without the need for elaborate measuring equipment. In particular, the size of dots used to embed invisible information in images can be accurately controlled.

Abstract: An image forming apparatus is provided. The image forming apparatus includes a mounting part configured to allow plural types of cartridges having different initial capacities of developing agent to be detachably mountable therein; a light emitting device configured to emit light into the cartridge mounted in the mounting part; a light receiving device configured to receive light emitted from the light emitting device and passed through an inside of the cartridge; a determining unit configured to determine that a replacement time of the cartridge has been reached when a ratio of time, during which an output value of the light receiving device exceeds a light reception reference value, exceeds a determination threshold value. The image forming apparatus or the cartridges are configured such that the determination of the replacement time changes according to the initial capacity of the cartridge.

Abstract: An imaging apparatus includes a toner cartridge within a housing having a rotatable shaft, a cam rotatably mounted on the shaft, an optical sensor mounted on the housing having an emitter and a receiver forming an optical path therebetween, and a flag mounted on the housing having a first arm and a second arm. The optical sensor has an output that changes when the optical path changes from blocked to unblocked and from unblocked to blocked. The flag has a home position where the first arm is disposed in the rotational path of the cam and the second arm either blocks the optical path or unblocks the optical path. Rotation of the rotatable shaft causes the cam to engage and disengage the first arm causing the second arm to change from blocking the optical path to unblocking the optical path or vice versa.

Abstract: A toner containing section contains toner, and includes a toner stirring member penetrating the toner containing section for stirring the toner. A rotation member is attached to the toner stirring member and revolves around a rotational shaft of the toner stirring member. A pushing member revolves around the rotational shaft of the toner stirring member to push the rotation member. A stopper section having a stopper body is provided to contact the rotation member. An optical detection device is provided to detect the rotation member temporarily stopping at the stopper section. The rotation member separates from the pushing member by own weight and stops at the stopper section waiting for arrival of the pushing device thereon when an amount of toner remaining in the toner containing section decreases to a prescribed level and the pushing member arrives at an upper dead point. The toner stirring member is formed in a crank sate partially plunging into the toner.

Abstract: In an embodiment of the present invention, an image forming apparatus includes a transfer belt that primarily transfers a toner image formed on a photosensitive drum; a secondary transfer unit including a transfer mechanism portion that secondarily transfers the primarily transferred toner image to a paper; an optical sensor that detects a reference toner image on the transfer belt; and a shutter that protects a detection face of the optical sensor, wherein a separation/contact mechanism portion disposed so as to be brought into contact with both of the shutter and the secondary transfer unit is provided, and the separation/contact mechanism portion allows the shutter to move so as to open and allows the secondary transfer unit to move so as to separate from the transfer belt when the reference toner image is detected by the optical sensor, and allows the shutter to move so as to separate from the transfer belt when the secondary transfer unit is drawn out from an apparatus main body.

Abstract: A method and system for performing document image correction using a document reader is disclosed. The method includes generating a document image representative of a document having a deformation; decoding an optical pattern embedded in the document from the document image to determine an optical signature for the document; receiving document classification data associated with the optical signature; and applying an image correction technique to the document image based on the document classification data to generate a corrected document image. A document capable of being read by a document reader is also disclosed. The document includes a substrate and an optical pattern embedded on the substrate. The optical pattern is part of a background pattern printed on the substrate. The optical pattern defines an optical signature unique to the particular class of document and is associated with document classification data for the document.

Abstract: A density measuring device includes a moving member that can be moved in a liquid, a light emitting member and a light receiving member that receives light emitted by the light emitting member. A gap part in which the moving member is disposed in a path of light emitted from the light emitting member can be moved. A density measuring unit measures the density of the liquid based on the result of output of the light receiving member for a case where the moving member is located in the path of light emitted from the light emitting member and a case where the moving member is not located in the path of light emitted from the light emitting member.

Abstract: In an image forming apparatus having a toner density sensor which emits light to a developer carried on a developing sleeve and which detects developer density by a reflection output value from the developer, when a reflection output value when the developer is initially set with respect to the illumination light of the toner density sensor is defined as A and a reflection output value of a region of at least the developing sleeve which is opposed to the toner density sensor when the developer is not carried on the developing sleeve is defined as B, a value of B/A is in a range of 0.3<B/A<2.

Abstract: An image forming apparatus capable of setting a criterion individually for respective image forming apparatuses, which is used in determining whether or not a developer is properly supplied to a developing unit, thereby stabilizing a developer toner density. With a shutter member closed, reflection light from a reflection sheet is received by a toner density detection sensor, and an output voltage is stored in a memory. After the shutter member is opened, reflection light from a developing sleeve is received by the sensor, and an output voltage is stored in the memory. If an amount of change in voltage per unit toner density calculated based on the output voltages does not fall within a predetermined range, an operation of a main unit of the image forming apparatus is stopped. If the amount of voltage change falls within the predetermined range, the amount of voltage change is stored in the memory.

Abstract: An image forming apparatus which is capable of decreasing the failure rate by improving a photocatalytic material and utilization efficiency thereof, and by decomposing substances that cannot be completely removed with a cleaning member or by not causing the substances to adhere. A light emitting unit irradiates an object to be irradiated with light. A light receiving unit receives reflected light from the irradiated object. A protection sheet containing a photocatalytic material is disposed so as to cover the light emitting unit and light receiving unit. The light emitting unit emits light of a wavelength range adapted to a bandgap width of the protection sheet, and the light receiving unit has sensitivity in a wavelength range of light emitted from the light emitting unit.

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 is described. The image forming apparatus includes a first casing accommodating a developing agent and having a first opening, an agitating member rotatably provided in the first casing and agitating the developing agent, a detection device outputting a signal in response to receiving of detection light passing through the first casing, and a control unit detecting an amount of the developing agent accommodated in the first casing and the position of the agitating member on the basis of the signal output from the detection device.

Abstract: A light emitting device and light receiving device are positioned to face each other to sandwich the developer cartridge. A pair of light transmitting tubes is installed in the casing of a developer cartridge. Light emitted from the light emitting device travels inside the casing via the light transmitting tubes and is received by the light receiving device. The direction of light traveling through light transmitting tubes changes along the light path to the light receiving device. When a developer cartridge is attached to the housing, toner blocks light from traveling through the toner chamber to the light receiving device. When the toner is consumed and the developer cartridge is ready to be replaced, light passes through the toner chamber and is received by the light receiving device, prompting exchange of the developer cartridge.

Abstract: A multi-color image-forming apparatus having image-forming sections for a plurality of different colors can include an optical sensor having a light-casting section that casts single polarized light and a light-receiving section that receives polarized light different from the cast light. A pattern for detecting toner positions can be used in which toner having high reflectance to a particular light emission wavelength is independently formed. In addition, other patterns in which toner having low reflectance to the particular light emission wavelength are partially formed on a central portion of the pattern of high reflection toner by using the high reflection toner as a foundation. The apparatus can detect each toner pattern by the optical sensor to correct the color shift of each color.

Abstract: Provided are a light-emitting portion having a light-emitting member and a light emergence surface through which light from the light-emitting member emerges, and a light-receiving portion having a light incidence surface through which the light from the light-emitting member enters and a light-receiving member that detects the light entering through the light incidence surface. The light-emitting portion and the light-receiving portion can make relative movement between a measurement position in which the light emergence surface and the light incidence surface make contact with each other and a waiting position in which the light emergence surface is away from the light incidence surface. When the light-emitting portion and the light-receiving portion are in the measurement position, the light emergence surface and the light incidence surface make contact with each other at a point.

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 reference developing image is formed on a photoreceptor drum under an image forming condition measured in advance, and the density of this reference developing image is detected. A development bias voltage is corrected based on the detection result, and when a correction value of the development bias voltage exceeds a predetermined range, a reference output voltage of an ATC sensor for detecting the density of toner in a developing device is corrected based on the detected value of humidity around the developing device, the frequency of use of the apparatus, and the agitation stress of developer.

Abstract: A powder transferring apparatus provided with a powder electrostatic transferring device includes a plurality of transferring electrodes configured to generate an electric field for transferring the powder by an electrostatic force including a powder transferring amount detecting device to detect an amount of powder on a surface of the powder electrostatic transferring device.

Abstract: An image forming method and apparatus capable of implementing accurately and constantly an improved conversion of the amount of toner adhesion over the entire range of the amount of adhesion.

Abstract: A method for determining printing ink usage efficiency (weight of ink required to print a given area) in a printing process is disclosed where the method is based on the analysis of pigment in the printed ink.

Abstract: An image forming apparatus, including a surface-traveling latent image bearer bearing a latent image on the surface thereof; an image developer feeding a toner in a two-component developer including the toner and a carrier to the latent image in a developing area facing the latent image bearer to develop the latent image to form a toner image, including a developer stirrer and feeder circulating the two-component developer in circulation paths while stirring the two-component developer, including a driver independently driving the first and the second stirring and feeding members; a transferer transferring the toner image onto a recording material; and a controller controlling the driver such that an amount of the two-component developer fed by the second stirring and feeding member per unit time is relatively larger than that of the two-component developer fed by the first stirring and feeding member when a predetermined increase condition of stirring is satisfied.

Abstract: An apparatus to detect the remaining amount of developer in a developing unit is provided. The apparatus includes a light emitting prism and a light receiving prism placed opposite to each other in a developer store space of the developing unit and forming a light emitting path and a light receiving path, respectively. A light emitting element irradiates light through the light emitting prism, and a light receiving element receives a light signal through the light receiving prism. An antistatic agent is coated on a light emitting window of the light emitting prism and a light receiving window of the light receiving prism, respectively, to substantially prevent developer from attaching on the light emitting window and the light receiving window.

Abstract: A developer accommodating apparatus, a developing apparatus and an image forming apparatus are provided capable of obtaining detection stability of irregular reflection light. The developing apparatus of the present invention comprises an accommodating section to accommodate developer of predetermined quantity, a light emitting section to emit light toward outside; and a light shading section to shade the light emitted from the light emitting section according to the predetermined quantity of the developer in the accommodating section.

Abstract: A developer supply container detachably mountable to a main assembly of an image forming apparatus, with the image forming apparatus including a remaining amount detecting portion for detecting an amount of remaining developer by receiving light from a light emitting portion by a light receiving portion. The developer supply container includes a container body for containing a developer. The developer supply container also includes a light guiding member including an incident portion for receiving light from the light emitting portion and for guiding the light into the container body, an emergent portion for guiding the light having passed through the container body toward the light receiving portion, and a connecting portion connecting the incident portion and the emergent portion.

Abstract: A toner quantity measuring device, a method of measuring toner quantity and an image forming apparatus are provided that can accurately measure the toner quantity in an environmentally friendly manner, without having to make contact with a toner carrier and within a shortened period of time. The toner quantity measuring device is designed to measure the quantity of the toner T on a developing roller 510 which carries coloring agent-containing toner T in the form of a thin layer. The toner quantity measuring device is provided with a chromaticity detector 3 for detecting average chromaticity of the light which is irradiated from a light source 2 onto the developing roller 510 and then reflected by the developing roller 510, and a calculator 4 for calculating the toner quantity based on the average chromaticity detected by the chromaticity detector 3.

Abstract: A process cartridge detachably mountable to a main assembly of an apparatus, includes a drum, a developing member, a cartridge frame including a developer accommodating portion, a first light guide adjacent one end of the cartridge frame and a leading end with respect to a cartridge mounting direction and including a light entrance portion opposed to an emitting portion to receive detecting light when the process cartridge is mounted to the main assembly and guiding the detecting light to cross with a developer accommodating space in the developer accommodating container, a second light guide adjacent the one end and the leading end, and including a light exit portion and directing, the detecting light having passed through the developer accommodating space to the light receiving portion, and a memory member communicatable with the main assembly and adjacent the one end o and the leading and including a cartridge electrical contact.

Abstract: An optical density sensor disposed over a target surface in an image formation apparatus comprises an integrating cavity having a diffuse, reflective interior surface and a view port formed therein. An optical source directs light through the view port onto the target surface, without striking any interior surface of the cavity. Light reflected from the target surface is detected by an optical detector disposed within the cavity. The optical source may be disposed in a collimator, which may extend into the interior of the cavity, and may include a lens. A circuit card which may include an optical detector sensing circuit may be disposed proximate the optical detector. A compensating slot formed in the cavity may allow some reflected light to directly impact the optical detector as the gap between the cavity and the target surface increases.

Abstract: The image forming apparatus, to which a developing apparatus for developing a latent image on an image bearing member corresponding to image information is detachably attachable, includes, a first detection device for detecting an amount of developer in the developing apparatus; a second detection device for detecting a utilized amount of the developer in the developing apparatus based upon the image information, and a processing unit for judging a utilized amount level of the developing apparatus based upon results of detection of the first detection device and the second detection device, wherein the processing unit judges the utilized amount level of the developing apparatus using the result of detection of the first detection device and the result of detection of the second detection device until the result of detection of the first detection device reaches a predetermined value, and judges the utilized amount level of the developing apparatus using the result of detection of the first detection device af

Abstract: A developing apparatus is for developing a latent image formed on an image bearing member. The apparatus includes: a developer accommodating portion for accommodating the developer; a developing device for developing the latent image; a light transmitting portion, provided in the developer accommodating portion, for transmitting light for detecting a remaining amount of the developer; a first developer feeding member, provided in the developer accommodating portion, for feeding the developer toward the developing means by rotation thereof; and a second developer feeding member for feeding the developer onto a light transmission surface of the light transmitting portion after the first developer feeding member rubs the light transmission surface by a free end with respect to a radial direction of the rotation. The second developer feeding member is provided on a rotation shaft which is also a rotation shaft of the first developer feeding member.

Abstract: A method for sensing toner concentration in a developer housing with an optical system containing developer material including toner and carrier, the method, including: emitting light with the optical system through a viewing window in the developer housing onto developer material in the housing; sensing the light reflected off the developer material with the optical system; calculating a toner concentration measurement based upon the sensed light reflected off the developer material; and compensating the toner concentration measurement to account for optical variation due to the developer material condition.

Abstract: An apparatus and method for determining toner concentration of a sample comprised of toner and carrier, including exposing the sample to light; the exposing includes emitting light at a predefined wavelength based upon the color of the toner; detecting the light reflected off the sample with an optical sensor; and determining the toner concentration of the sample base upon the light reflected off the sample.

Abstract: A toner conveying device includes a toner container that contains toner, a toner discharge urging device that urges the discharge of the toner from the toner container, a toner conveying mechanism that conveys the toner discharged from the toner container through a toner conveying path member, and a flow amount detecting device that detects the flow amount of the toner conveyed in the toner conveying path member.

Abstract: A developer container for accommodating a developer used for developing an electrostatic latent image formed on an electrophotographic photosensitive member by a developing member for developing the electrostatic latent image includes, a first light-transmitting window for guiding detection light emitted from a light emitting member provided in a main body of an image forming apparatus into the developer container, a second light-transmitting window for guiding the detection light entering from the first light-transmitting window and passing through the developer container to a photosensing member provided in the main body of the image forming apparatus, in order to detect the remaining amount of the developer accommodated within the developer container when the developer container is mounted in the main body of the image forming apparatus, and a rotatable feeding member including a stirring blade for feeding the developer within the developer container toward the developing member when rotating, and for remo

Abstract: A developer composition having improved noise signal ratio in an optical toner concentration sensing system, including a toner having a first diffuse reflectivity and a carrier having a second diffuse reflectivity wherein the difference between the first diffuse reflectivity and the second diffuse reflectivity is substantially high.

Abstract: An automatic slide feeder according to one embodiment of the present invention may comprise a housing configured to define an input slide tray, an output slide tray and a scan slide tray. A slide actuator operatively associated with the housing moves a slide from the input slide tray to the scan slide tray. A control system operatively associated with the slide actuator and a document scanner operates the document scanner to scan a slide positioned in the scan slide tray and operates the slide actuator to move a new slide from the input slide tray to the scan slide tray after the slide positioned in the scan slide tray has been scanned.

Abstract: A toner maintenance system for an electrophotographic developer unit, including a sump for storing a quantity of developer material comprised of toner material; a first member for transporting developer material from the sump, a viewing window, in communication with toner material, in the sump; an optical sensor, for measuring reflected light off the viewing window and toner material, and generating a signal indicative thereof. A toner concentration controller is adapted to receive a signal from the optical sensor and to generate an “Add Toner” signal to replenish toner material in the sump.

Abstract: A toner maintenance system for an electrophotographic developer unit, including a sump for storing a quantity of developer material a sump for storing a quantity of developer material comprised of toner material; a first member for transporting a mixture of developer material and toner particles from the sump, a viewing window, in communication with toner material, in the sump; an optical sensor, device for measuring reflected light off the viewing window and toner material, and generating a signal indicative thereof. A toner concentration controller is adapted to receive a signal from the sensor and to generate an “Add Toner” signal to replenish toner in the sump.

Abstract: An optical guide to be used for detecting the remaining amount of developer contained in a developer containing portion includes a blocking portion for blocking an opening formed in the developer containing portion when the optical guide is fitted to the developer containing portion, an optical guide portion for guiding light, which is formed on a side to be positioned on the outside of the developer containing portion with respect to the blocking portion when the optical guide is fitted to the developer containing portion, an outside inclining surface inclining toward the side, on which the optical guide portion is formed, with respect to the blocking portion, the outside inclining surface being formed at an end portion of the optical guide portion on the blocking portion side in a lengthwise direction of the optical guide portion, and an inside inclining surface portion inclining toward a direction intersecting the lengthwise direction of the optical guide portion, the inside inclining surface portion being

Abstract: A method and apparatus for measuring a substance concentration in a liquid wherein a continuously variable thickness of the liquid is formed, and light is emitted such that a portion of the light passes through the formed continuously variable thickness of the liquid, an electrical signal is generated according to the portion of the light that passes through the formed continuously variable thickness of the liquid, and the substance concentration in the liquid is determined based on the generated electrical signal.

Abstract: A method of detecting a developer remaining amount for successively detecting the remaining amount of a developer used for developing an electrostatic latent image formed on an electrophotographic photosensitive member, the method including successively detecting the remaining amount of developer based on a period of time for which a light is blocked by a developer carried by a developer carrying member, wherein the developer is carried by the developer carrying member to a position in which the developer blocks the light that has entered a developer containing portion from a first light transmission opening of said a developer containing portion for containing the developer when the light transmitted from the first light transmission opening to an inside of the developer containing portion is transmitted from a second light transmission opening of the developer containing portion to an outside of the developer containing portion.