Abstract: An image forming apparatus includes an image bearing member which bears an electrostatic latent image, a development device which includes a developer bearing member conveying developer, a developing container containing the developer, and a stirring member stirring the developer inside the developing container. In addition, a first detecting portion detects information regarding humidity of the developer, a second detecting portion is disposed at a different position from the first detecting portion and detects information regarding humidity of the developer, and a controller starts image forming after driving the stirring member for a predetermined period after receiving an image forming signal. The controller controls to extend the predetermined period when a difference between the detecting result from the first detecting portion and the second detecting portion is larger than a predetermined value.

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: A developing apparatus includes a developing container for containing a developer; a rotatable developer carrying member provided at the position of the developing container opposed to an image bearing member and configured to carry the developer into a developing zone where the developer carrying member is opposed to the image bearing member; and a guiding portion provided opposed to a carrying region, with respect to an axial direction of the developer carrying member, where the developer carrying member carries the developer, in a side of the developing container remote from the image bearing member, the guiding portion being capable of guiding the developer from an end portion of the developer carrying member with rotation of the developer carrying member.

Abstract: A controller which 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; wherein 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; wherein 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; and wherein 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: An image forming apparatus includes an image forming unit configured to form a toner image, a first detection unit configured to detect a height of the toner image and output height information, a second detection unit configured to detect a density of the toner image, a storage unit configured to store data for converting height information to density information, a determination unit configured to convert the height information detected by the first detection unit to the density information based on the stored data and determine an image forming condition of the image forming unit based on the converted density information, and an updating unit configured to, in an updating mode for updating the stored data, update the stored data based on the height information of a patch toner image, which is formed by the image forming unit, being output by the first detection unit and a density of the patch toner image detected by the second detection unit.

Abstract: A representative configuration of an image forming apparatus has a plurality of developing devices, each of which develops an electrostatic latent image formed on a photosensitive drum into a toner image using developer of plural colors. The image forming apparatus includes a density sensor which detects the amount of toner of the toner image for each color. In a case where it is determined that the amount of toner of any color departs from a predetermined range based on the detection result of the density sensor, development conditions of the rest of the developing devices, other than the developing device departing from the predetermined range, are changed such that the image densities developed by the respective developing devices are equal to each other.

Abstract: An image forming apparatus includes an image forming unit configured to form a toner image on an image bearing member, a first detection unit configured to detect a height of the toner image formed according to a predetermined image forming condition by the image forming unit, a determination unit configured to determine an image forming condition of the image forming unit according to a detection result of the first detection unit, a second detection unit configured to detect a density of the toner image formed according to a predetermined image forming condition by the image forming unit, and a correction unit configured to correct the image forming condition of the image forming unit determined by the determination unit based on the density of the toner image detected by the second detection unit.

Abstract: An image forming apparatus includes an image forming unit configured to form a toner image on an image bearing member, a first detection unit configured to detect a height of the toner image formed according to a predetermined image forming condition by the image forming unit, a determination unit configured to determine an image forming condition of the image forming unit according to a detection result of the first detection unit, a second detection unit configured to detect a density of the toner image formed according to a predetermined image forming condition by the image forming unit, and a correction unit configured to correct the image forming condition of the image forming unit determined by the determination unit based on the density of the toner image detected by the second detection unit.

Abstract: An image forming apparatus of the present invention includes a photosensitive drum, a development sleeve, and screws. The image forming apparatus further includes a development device that develops the electrostatic latent image born on the photosensitive drum using the developer and a controller that is able to execute a mode in which the screws are idly rotated before an image forming operation in association with an image formation start. The image forming apparatus further includes temperature and humidity sensors that acquire information regarding humidity of the developer at different positions inside the developing container. The controller determines the execution or non-execution of the mode or a driving condition of the screws at the time of the mode based on data acquired by the temperature and humidity sensors.

Abstract: An image forming apparatus includes an image bearing member for bearing a latent image; a developing device, including a developer carrying member for carrying and feeding a developer including toner and a carrier to a developing position in which the developer opposes the image bearing member, for developing the latent image formed on the image bearing member; a discharging portion for permitting discharge of an excessive developer present in the developing device by supplying the developer into the developing device; a feeding member for feeding the developer in the developing device; a controller for controlling a forced discharging operation for discharging the excessive developer from the discharging portion by changing a driving condition of at least one of the developer carrying member and the feeding member; and a detecting device for detecting information correlating to flowability of the developer in the developing device.

Abstract: A representative configuration of an image forming apparatus according to the invention is provided. The image forming apparatus has a plurality of developing devices which develops an electrostatic latent image formed on a photosensitive drum into a toner image using developer of plural colors. The image forming apparatus includes a density sensor which detects the amount of toner of the toner image for each color. In a case where it is determined that the amount of toner of any color departs from a predetermined range based on the detection result of the density sensor, a development condition of the rest developing devices other than the developing device departing from the predetermined range is changed such that the image densities developed by the respective developing devices are equal to each other.

Abstract: An image forming apparatus includes an image forming unit configured to form a toner image on an image bearing member, a first detection unit configured to detect a height of the toner image formed according to a predetermined image forming condition by the image forming unit, a determination unit configured to determine an image forming condition of the image forming unit according to a detection result of the first detection unit, a second detection unit configured to detect a density of the toner image formed according to a predetermined image forming condition by the image forming unit, and a correction unit configured to correct the image forming condition of the image forming unit determined by the determination unit based on the density of the toner image detected by the second detection unit.

Abstract: An image forming apparatus includes an image bearing member for bearing a latent image; a developing device, including a developer carrying member for carrying and feeding a developer including toner and a carrier to a developing position in which the developer opposes the image bearing member, for developing the latent image formed on the image bearing member; a discharging portion for permitting discharge of an excessive developer present in the developing device by supplying the developer into the developing device; a feeding member for feeding the developer in the developing device; a controller for controlling a forced discharging operation for discharging the excessive developer from the discharging portion by changing a driving condition of at least one of the developer carrying member and the feeding member; and a detecting device for detecting information correlating to flowability of the developer in the developing device.

Abstract: A developing apparatus includes a developer container for containing a developer; a first screw, provided in a first screw, provided in a first chamber in the developer container, for feeding the developer; a second screw, provided in a second chamber in the developer container, for feeding the developer in a direction opposite from that of the first screw; an opening through which the developer is moved between the first chamber and the second chamber; and a developer carrying member, provided in the first chamber, for carrying the developer to effect development of an electrostatic image. At least one of said first screw and said second screw has a multiple thread screw portion having a number n of threads and a thread pitch P.

Abstract: An image forming apparatus includes a developing apparatus for developing an electrostatic image with a developer comprising at least a toner and a first external additive, the developing apparatus including a plurality of developing devices, containing toners different in color or lightness from each other, in which at least two developing devices contain a dark color toner and a light color toner which have an identical hue and different lightnesses and the developing device containing the light color toner is subjected to a developing operation prior to another developing device; a first transfer apparatus for sequentially transferring toner images, which have been developed by the plurality of developing devices, onto an intermediary transfer member; and a second transfer apparatus for transferring the toner images from the intermediary transfer member all together onto a transfer medium The first external additive includes particles having an aspect ratio of not less than 1.0 and not more than 1.

Abstract: An image forming apparatus includes a developing apparatus for developing an electrostatic image with a developer comprising at least a toner and a first external additive, the developing apparatus including a plurality of developing devices, containing toners different in color or lightness from each other, in which at least two developing devices contain a dark color toner and a light color toner which have an identical hue and different lightnesses and the developing device containing the light color toner is subjected to a developing operation prior to another developing device; a first transfer apparatus for sequentially transferring toner images, which have been developed by the plurality of developing devices, onto an intermediary transfer member; and a second transfer apparatus for transferring the toner images from the intermediary transfer member all together onto a transfer medium The first external additive includes particles having an aspect ratio of not less than 1.0 and not more than 1.

Abstract: In a developing apparatus provided with a developer container containing a developer, a rotary member holding the developer container and rotatively moving it relative to a developing position, an opening portion provided in the developer container and through which the developer is supplied or discharged, a valve swingable to open and close the opening portion, and a restricting wall restricting the movement of the valve in an opening direction by contacting with the valve when the valve is in an opened position, an irregularity portion is provided on at least one of the contact surface of the valve with the restricting wall and the contact surface of the restricting wall with the valve.

Abstract: An image forming apparatus includes a developing apparatus for developing an electrostatic image with a developer comprising at least a toner and a first external additive, the developing apparatus including a plurality of developing devices, containing toners different in color or lightness from each other, in which at least two developing devices contain a dark color toner and a light color toner which have an identical hue and different lightnesses and the developing device containing the light color toner is subjected to a developing operation prior to another developing device; a first transfer apparatus for sequentially transferring toner images, which have been developed by the plurality of developing devices, onto an intermediary transfer member; and a second transfer apparatus for transferring the toner images from the intermediary transfer member all together onto a transfer medium The first external additive includes particles having an aspect ratio of not less than 1.0 and not more than 1.

Abstract: The image forming apparatus includes a developing device, a movable member, a replenishment device, a developer replenishment path, and a conveyance screw so arranged within the developer replenishment path as not to come into contact with the internal wall of the developer replenishment path, wherein X (g) representing the quantity of the developer for replenishment present in the clearance section between the developer replenishment path and the conveyance screw, Y (g) representing the quantity of the developer in the developing device, Q(?C/mg) representing the absolute value of the electric charge per unit weight of the toner in the developing device, and A(?C/mg) representing the absolute value of the electric charge per unit weight of the toner relative to a 1% variation in the toner density satisfy the condition of a relationship of X?(Y×Q)/(500×A).

Abstract: The developing apparatus includes developer containing parts and a replenishment portion. The developer containing parts contains a developer circularly conveyed in the developer containing parts. The replenishment portion includes a replenish aperture and a regulation surface. The replenishment portion merges a replenishment agent passing through the regulation surface with the developer in the developer containing part. In the developing apparatus, a wall surface of the replenishment portion, located on a downstream side in a developer conveyance direction in the developer containing part facing to the replenishment portion, is formed by being inclined with respect to the developer conveyance direction.