Abstract: A first embodiment of the system to detect the amount of toner includes a first and a second light pipe attached in a substantially parallel orientation from the top to the bottom of a sidewall in the toner reservoir. An infra-red light emitting diode illuminates the first light pipe. A rotatable auger has an attached first arm. A light bridge attached to the first arm is positioned so that during rotation of the auger, the light bridge moves adjacent to the first and the second light pipe as the light bridge moves from the top to the bottom of the toner reservoir. When the light bridge is outside of the toner and adjacent to the first and the second light pipe, light is transmitted between the first and the second light pipe. When the light bridge is inside of the toner, light transmission between the first and the second light pipe is interrupted. A circuit detects light transmitted from the second light pipe using a photodiode.

Abstract: A printer is provided with a transmit electrode and a receive electrode with a dry-toner cartridge located therebetween. The transmit and receive electrodes act as two plates of a capacitor, with the toner within the toner cartridge making up a portion of the dielectric between the two capacitor plates. An oscillating transmit signal is then applied to the transmit electrode, and a signal corresponding to the capacitance between the opposing electrodes is detected. The changing capacitance due to the changing toner quantity causes a change in the received signal. The value of the received signal is then converted into the quantity of toner residing between the opposing electrodes, and this quantity is displayed to the user. Arrangements of transmit and receive electrodes may be employed within the printer to not only sense the overall quantity of toner but the distribution of toner within the toner cartridge.

Abstract: An image transferring device incorporated in an image forming apparatus and capable of surely preventing a sheet from wrapping around a photoconductive element. The image transferring device includes a transfer belt contacting an image bearing member to form a nip portion and which is supported by first and second rollers. A contact electrode connected to a power source contacts the inner surface of the belt and is located downstream of the nip for applying a transfer bias to the belt. A discharge electrode is located downstream of the contact electrode and separate from the first and second rollers for dissipating transfer charge on the belt. A controller controls the power source such that a relation: I.sub.1 -I.sub.2 =I.sub.out is satisfied, where I.sub.1 is the transfer current, 1.sub.2 is the feedback current flowing from the discharge electrode and I.sub.out is constant.

Abstract: A method for controlling the density of microdots produced by a binary or multilevel electrophotographic device. In one example, the toner concentration in a two-component developing system is modified as to keep the toner charge Q/M approximately constant. The toner charge is indirectly assessed. This allows to achieve consistent output densities, irrespective of the environmental parameters, such as relative humidity and temperature.

Abstract: There is provided a developing agent replenishing method in a digital photographic printer in which an image is exposed onto a photosensitive material based on digital data containing image data and the exposed photosensitive material is developed by a developing agent, comprising the steps of: (a) calculating an image rate of an image to be exposed based on the digital data, the image rate being a parameter for obtaining, based on at least one of a density characteristic of the image to be exposed, depth of the image to be exposed, and contrast of the image to be exposed, a replenishment quantity of a developing agent used for development processing of the image to be exposed; (b) calculating a replenishment quantity of the developing agent based on the calculated image rate; and (c) effecting replenishment of the developing agent on the basis of the calculated replenishment quantity.

Abstract: A toner remaining detection unit is provided that displays the amount of remaining toner according to the number of transitions from a low state to a full state. This operation ensures that the amount of remaining toner is not determined incorrectly when toner fluidity is reduced, while change of remaining state display is minimized when toner fluidity is good. If toner is not being stirred, initialization at toner replacement is performed. If the toner is being stirred, toner display control processing is performed. If neither an empty nor a low state is detected and a counter value does not reach 15, low display is turned off. If the previous state was a low state, 1 is added to the count value. When a low state is detected, or when a low state is not detected but the counter value reaches 15, the low display is turned on.

Abstract: A printer specific stream of bits is received, before or while the printing of a print job, and translated into a pixel count specific to the print job and indicative of the anticipated toner usage for the print job. This pixel count then is added to a global pixel count indicative of toner usage of jobs printed since a global pixel counter was reset.

Abstract: A developing device is constructed by a developing unit for developing an electrostatic latent image on an image holding member, a developing agent containing unit for containing a developing agent which is supplied to the developing unit, an agitator, provided in the developing agent containing unit, for agitating the developing agent, a detecting sensor for detecting a residual amount of developing agent in the developing agent containing unit, and a determining device for determining the residual amount of developing agent at a plurality of levels on the basis of an output state of the detecting sensor in a predetermined time range. The determining device determines the residual amount of developing agent on the basis of a ratio of an output time of a developing agent presence state of the detecting sensor and an output time of a developing agent absence state in the predetermined time range.

Abstract: In an image forming apparatus using dry toner, a toner replenishing device includes cleaning means for cleaning the sensing surface of remaining toner sensing means. The cleaning means is driven by the same drive source as agitating means for agitating the toner. To clean the sensing surface, the cleaning means is driven in a particular manner different from a manner for usual toner replenishment. While the cleaning means cleans the sensing surface, the output signal of the remaining toner sensing means is detected. The device achieves highly accurate toner concentration control and toner end detection at the same time.

Abstract: An image formation apparatus for forming a full color image in the four colors of cyan, magenta, yellow and black has a optical ATDC sensor attached in a cyan developing device to control the toner density under optical ATDC. A black developing device has the toner density controlled by AIDC. A standard develop efficiency .eta.STD of the cyan developing device obtained as a result of the AIDC is compared with a develop efficiency .eta. of black toner. The toner supply amount of the black developing device is determined according to the comparison result to supply the toner. Thus, an image formation apparatus is provided that can detect at favorable accuracy the toner density of a developing device incorporating a developer of which the toner density cannot be detected using optical ATDC to supply a required amount of toner.

Abstract: In an electrostatographic process wherein images are formed on an electrostatic image supporting medium and developed by a development station having a developer formed of a mixture of toner and carrier particles, there is provided apparatus for controlling various processing control parameters in response to formation of a toned patch on the medium. The apparatus includes a first feedback controller that processes signals related to the parameter toning contrast in accordance with a closed loop control of this parameter. The first feedback controller serves as a toning contrast controller and outputs a first signal representing toner concentration set point in response to closed loop control of toning contrast. The apparatus also includes a second feedback controller means that is slaved to the first feedback controller and serves as a toner concentration (TC) controller.

Abstract: An apparatus and method for detecting an empty condition of toner cartridges containing toner for copiers, fax machines, printers and the like is disclosed. The cartridges may be mounted to a rotary developing device. According to one embodiment, when a toner cartridge has been rotatably positioned to a developing position, an empty condition is detected by emitting light into the toner cartridge and detecting the light coming out of its bottom. To accomplish this detection, a light source and a light sensor are fixedly located near a bottom corner of the toner cartridge at the developing position. Light is emitted into the toner cartridge at a predetermined oblique angle with respect to a side wall of the toner cartridge. Light exits out from the bottom wall if a predetermined amount of toner does not exist in the toner cartridge. Due to the oblique angle, the distance between the light source and the light sensor is substantially reduced and provides an accurate measurement.

Abstract: A developing device incorporating a developer supply unit and a developer discharge section, in which a supply developer including a mixture of toner and carrier is successively supplied to a developer container from the developer supply unit and a deteriorated developer in the developer container is discharged through the developer discharge section. The developer supply unit has a sponge roller for selectively attracting toner to a surface thereof, a magnet roller for selectively attracting carrier to a surface thereof, and a member for scraping and bringing the toner and carrier attracted to these rollers into the developer container. The developer including toner and carrier in a predetermined ratio is thus stably supplied to the developer container. In another example of the developer supply unit, agitating of the developer is performed while shovelling the developer deposited in a lower part of the unit by a transport screw.

Abstract: A toner density sensor detects the state where a toner cartridge is empty and the toner density in a developing unit is therefore low. In accordance with the sensing output of the toner density sensor, the surface potential of a photosensitive drum is decreased. By this control, the carriers of the developing agent are prevented from being attracted onto the photosensitive drum during the period between the time when the toner cartridge becomes empty and the toner density begins to decrease and the time when the copying operation stops due to the toner empty state. Hence, the images formed during that period are not poor in quality.

Abstract: Deteriorating developer including toner and carrier in a developer container is replaced by supplying carrier developer including carrier from a developer supply unit and discharging an amount of the deteriorated developer corresponding to the amount of the supplied carrier developer through a discharge opening formed in the developer container by opening a cover. The cover is driven by a solenoid for discharging. With this structure, even when the amount of developer in the developer container is changed and the surface level of the developer is changed, a predetermined amount of deteriorated developer is accurately discharged according to the driving of the cover. It is thus possible to control in a desired manner the replacement ratio of deteriorated developer in the developer container to new developer to be supplied. With this configuration, it is possible to maintain the charge of developer substantially uniform and good image quality of copies.