Abstract: When, in a state where a developer borne by a developer bearing member is sandwiched by an opposing portion of an image bearing member and the developer bearing member, C denotes capacitance between the image bearing member and the developer bearing member, ?V denotes a development contrast, Q/S denotes a charge amount per unit area of the developer borne by the developer bearing member, and ?v denotes a peripheral velocity ratio which is a ratio of a peripheral velocity of the developer bearing member to a peripheral velocity of the image bearing member, a first peripheral velocity ratio is set so that |Q/S×?v|?|C×?V| is satisfied, and a second peripheral velocity ratio which is larger than the first peripheral velocity ratio is set so that |Q/S×?v|>|C×?V| is satisfied.

Abstract: An image forming apparatus includes an image bearing member, a developer bearing member, a driving unit, a latent image forming unit that forms an electrostatic image having light area potential and a dark area potential, and an application unit that applies a developing bias. The driving unit drives the image bearing member and the developer bearing member in a first peripheral speed ratio and a second peripheral speed ratio larger than the first peripheral speed ratio. The image forming apparatus further includes an acquiring unit acquiring information related to a change in an electrostatic capacitance of the image bearing member and a determining unit determining a developing contrast according to the electrostatic capacitance. The determining unit determines the developing contrast based on the acquired information when the driving unit drives the image bearing member and the developer bearing member in the second peripheral speed ratio.

Abstract: An image forming apparatus includes an image bearing member, a developer bearing member, a driving unit, a latent image forming unit that forms an electrostatic image having light area potential and a dark area potential, and an application unit that applies a developing bias. The driving unit drives the image bearing member and the developer bearing member in a first peripheral speed ratio and a second peripheral speed ratio larger than the first peripheral speed ratio. The image forming apparatus further includes an acquiring unit acquiring information related to a change in an electrostatic capacitance of the image bearing member and a determining unit determining a developing contrast according to the electrostatic capacitance. The determining unit determines the developing contrast based on the acquired information when the driving unit drives the image bearing member and the developer bearing member in the second peripheral speed ratio.

Abstract: An image forming apparatus includes a main assembly, a first cartridge including an image bearing member, a second cartridge including a developing member, a developer supplying member provided in the second cartridge, and a controller for changing a polarity of a developer supply amount control bias which is a difference between the developing bias and the developer supplying bias depending on a print ratio based on an inputted image data. The controller changes the polarity of the developer supply amount control bias depending on at least one of a use history of the first cartridge and a use history of the second cartridge and on the print ratio.

Abstract: An image forming apparatus includes an image bearing member, a developer bearing member, a driving unit, a latent image forming unit that forms an electrostatic image having light area potential and a dark area potential, and an application unit that applies a developing bias. The driving unit drives the image bearing member and the developer bearing member in a first peripheral speed ratio and a second peripheral speed ratio larger than the first peripheral speed ratio. The image forming apparatus further includes an acquiring unit acquiring information related to a change in an electrostatic capacitance of the image bearing member and a determining unit determining a developing contrast according to the electrostatic capacitance. The determining unit determines the developing contrast based on the acquired information when the driving unit drives the image bearing member and the developer bearing member in the second peripheral speed ratio.

Abstract: When, in a state where a developer borne by a developer bearing member is sandwiched by an opposing portion of an image bearing member and the developer bearing member, C denotes capacitance between the image bearing member and the developer bearing member, ?V denotes a development contrast, Q/S denotes a charge amount per unit area of the developer borne by the developer bearing member, and ?v denotes a peripheral velocity ratio which is a ratio of a peripheral velocity of the developer bearing member to a peripheral velocity of the image bearing member, a first peripheral velocity ratio is set so that |Q/S×?v|?|C×?V| is satisfied, and a second peripheral velocity ratio which is larger than the first peripheral velocity ratio is set so that |Q/S×?v|>|C×?V| is satisfied.

Abstract: An image forming apparatus includes an image bearing member, a developer bearing member, a driving unit, a latent image forming unit that forms an electrostatic image having light area potential and a dark area potential, and an application unit that applies a developing bias. The driving unit drives the image bearing member and the developer bearing member in a first peripheral speed ratio and a second peripheral speed ratio larger than the first peripheral speed ratio. The image forming apparatus further includes an acquiring unit acquiring information related to a change in an electrostatic capacitance of the image bearing member and a determining unit determining a developing contrast according to the electrostatic capacitance. The determining unit determines the developing contrast based on the acquired information when the driving unit drives the image bearing member and the developer bearing member in the second peripheral speed ratio.

Abstract: An image forming apparatus having a first mode and a second mode with respectively different rotational peripheral velocity ratios of a developer bearing member, stores a first lifetime threshold value of a developing apparatus corresponding to the first mode and a second lifetime threshold value of the developing apparatus corresponding to the second mode, updates a lifetime determination value of a developing apparatus on the basis of drive amount information when the developer bearing member operates in the first mode and second modes, performs a first determination related to a lifetime in the first mode on the basis of the first lifetime threshold value and the lifetime determination value, performs a second determination related to a lifetime in the second mode on the basis of the second lifetime threshold value and the lifetime determination value, and makes a notification on the basis of determination results.

Abstract: An image forming apparatus includes a main assembly, a first cartridge including an image bearing member, a second cartridge including a developing member, a developer supplying member provided in the second cartridge, and a controller for changing a polarity of a developer supply amount control bias which is a difference between the developing bias and the developer supplying bias depending on a print ratio based on an inputted image data. The controller changes the polarity of the developer supply amount control bias depending on at least one of a use history of the first cartridge and a use history of the second cartridge and on the print ratio.

Abstract: An image forming apparatus includes a motor configured to rotationally drive an image bearing roller and a developer bearing roller at a first peripheral velocity ratio and a second peripheral velocity ratio which is larger than the first peripheral velocity ratio. A development contrast formed between a developing bias to the developer bearing roller and a light-part potential formed on the image bearing roller in a case where a development operation is performed at the second peripheral velocity ratio is larger than a development contrast formed between the developing bias to the developer bearing roller and the light-part potential formed on the image bearing roller in a case where the development operation is performed at the first peripheral velocity ratio.

Abstract: An image forming apparatus includes an image bearing member, a developer bearing member, a driving unit, a latent image forming unit that forms an electrostatic image having light area potential and a dark area potential, and an application unit that applies a developing bias. The driving unit drives the image bearing member and the developer bearing member in a first peripheral speed ratio and a second peripheral speed ratio larger than the first peripheral speed ratio. The image forming apparatus further includes an acquiring unit acquiring information related to a change in an electrostatic capacitance of the image bearing member and a determining unit determining a developing contrast according to the electrostatic capacitance. The determining unit determines the developing contrast based on the acquired information when the driving unit drives the image bearing member and the developer bearing member in the second peripheral speed ratio.

Abstract: An image forming apparatus includes an image bearing member, a developer bearing member, a driving unit, a latent image forming unit that forms an electrostatic image having light area potential and a dark area potential, and an application unit that applies a developing bias. The driving unit drives the image bearing member and the developer bearing member in a first peripheral speed ratio and a second peripheral speed ratio larger than the first peripheral speed ratio. The image forming apparatus further includes an acquiring unit acquiring information related to a change in an electrostatic capacitance of the image bearing member and a determining unit determining a developing contrast according to the electrostatic capacitance. The determining unit determines the developing contrast based on the acquired information when the driving unit drives the image bearing member and the developer bearing member in the second peripheral speed ratio.

Abstract: An image forming apparatus includes an image bearing member, a developer bearing member, a driving unit, a latent image forming unit that forms an electrostatic image having light area potential and a dark area potential, and an application unit that applies a developing bias. The driving unit drives the image bearing member and the developer bearing member in a first peripheral speed ratio and a second peripheral speed ratio larger than the first peripheral speed ratio. The image forming apparatus further includes an acquiring unit acquiring information related to a change in an electrostatic capacitance of the image bearing member and a determining unit determining a developing contrast according to the electrostatic capacitance. The determining unit determines the developing contrast based on the acquired information when the driving unit drives the image bearing member and the developer bearing member in the second peripheral speed ratio.

Abstract: An image forming apparatus having a first mode and a second mode with respectively different rotational peripheral velocity ratios of a developer bearing member, stores a first lifetime threshold value of a developing apparatus corresponding to the first mode and a second lifetime threshold value of the developing apparatus corresponding to the second mode, updates a lifetime determination value of a developing apparatus on the basis of drive amount information when the developer bearing member operates in the first mode and second modes, performs a first determination related to a lifetime in the first mode on the basis of the first lifetime threshold value and the lifetime determination value, performs a second determination related to a lifetime in the second mode on the basis of the second lifetime threshold value and the lifetime determination value, and makes a notification on the basis of determination results.

Abstract: When, in a state where a developer borne by a developer bearing member is sandwiched by an opposing portion of an image bearing member and the developer bearing member, C denotes capacitance between the image bearing member and the developer bearing member, ?V denotes a development contrast, Q/S denotes a charge amount per unit area of the developer borne by the developer bearing member, and ?v denotes a peripheral velocity ratio which is a ratio of a peripheral velocity of the developer bearing member to a peripheral velocity of the image bearing member, a first peripheral velocity ratio is set so that |Q/S×?v|?|C×?V| is satisfied, and a second peripheral velocity ratio which is larger than the first peripheral velocity ratio is set so that |Q/S×?v|>|C×?V| is satisfied.

Abstract: In a state where a developer borne by a developer bearing member is sandwiched by an opposing portion of an image bearing member and the developer bearing member, C denotes capacitance between the image bearing member and the developer bearing member, ?V denotes a development contrast, Q/S denotes a charge amount per unit area of the developer borne by the developer bearing member, and Av denotes a peripheral velocity ratio, which is a ratio of a peripheral velocity of the developer bearing member to a peripheral velocity of the image bearing member. A first peripheral velocity ratio is set so that |Q/S×?v|?|C×?V| is satisfied, and a second peripheral velocity ratio which is larger than the first peripheral velocity ratio is set so that |Q/S×?v|>|C×?V| is satisfied.

Abstract: An image forming apparatus includes an image bearing member, a developer bearing member, a driving unit, a latent image forming unit that forms an electrostatic image having light area potential and a dark area potential, and an application unit that applies a developing bias. The driving unit drives the image bearing member and the developer bearing member in a first peripheral speed ratio and a second peripheral speed ratio larger than the first peripheral speed ratio. The image forming apparatus further includes an acquiring unit acquiring information related to a change in an electrostatic capacitance of the image bearing member and a determining unit determining a developing contrast according to the electrostatic capacitance. The determining unit determines the developing contrast based on the acquired information when the driving unit drives the image bearing member and the developer bearing member in the second peripheral speed ratio.

Abstract: An image forming apparatus includes an image bearing member on which an electrostatic latent image is formable, and a developing device including a developer carrying member, a container, and a supply roller. When the developing device including the developer carrying member, to which a lubricant different from the developer is applied, is used for the first time, a first initial operation of transferring the lubricant from the developer carrying member to the image bearing member together with the developer is performed. The image forming apparatus further includes a storage unit configured to store a suspension state when suspension is detected before the initial operation completes, and a controller configured to execute a second initial operation as an operation of resuming the suspended first initial operation on the basis of the stored suspension state.

Abstract: A vapor chamber having improved heat transfer capacity by efficiently returning the working fluid to the evaporating portion is provided. A hollow flat container 2 is formed by a base member 4 and a lid 3 closing an opening of the base member. Phase-changeable working fluid is held in the container, and fins 9 are arranged in the container to transmit heat of a heat generating object between the bottom plate of the base member and the lid. The fins are densely juxtaposed on an evaporating portion in comparison with the other fins juxtaposed on the outside of the evaporating portion.

Abstract: An image forming apparatus includes: an image bearing member; a developer carrying member configured to contact with the image bearing member and to be separated from the image bearing member; a control unit for controlling the image bearing member and the developer carrying member; and a contact member disposed in contact with the image bearing member. The control unit is configured to sequentially execute: (1) rotating the image bearing member at a first speed in a separated state; (2) switching the image bearing member and the developer carrying member from the separated state to a contact state in a state in which the image bearing member rotates at the first speed; and (3) rotating the image bearing member by decreasing a rotation speed of the image bearing member from the first speed to a second speed smaller than the first speed in the contact state.