Abstract: A control portion stops driving a developer carrying member at the end of a development process for a preceding image to be printed on the last sheet of a preceding copy and starts driving the developer carrying member when performing a development process for a subsequent image to be printed on the first sheet of the subsequent copy. Regardless of the length of a development driving suspension period after stopping driving the developer carrying member following the end of the development process for the preceding image until starting driving the developer carrying member to perform the development process for the subsequent image, the control portion maintains suspension of the driving of the developer carrying member during the development driving suspension period.

Abstract: An image forming apparatus includes a developing device, a container, a toner replenishment device, a toner conveyance detection portion, and a control portion. The toner replenishment device includes a plurality of toner replenishment paths through which toner in the container is conveyed and replenished to the developing device. The toner conveyance detection portion detects a toner conveyance error in toner conveyance performed by using the plurality of toner replenishment paths. In a case where the toner conveyance detection portion has detected a toner conveyance error in one of the toner replenishment paths that is in use, the control portion switches to another one of the toner replenishment paths to convey the toner.

Abstract: A two-component developer is used for developing an electrostatic latent image by a developing device, and contains toner and carrier. When a carrier resistance is R (?), and a saturation magnetization of the carrier is H (emu/g), then 14>log10R>0.135H is satisfied.

Abstract: A first developer contains a first toner and a first carrier containing first carrier particles. A second developer contains a second toner, and a second carrier containing second carrier particles. The first carrier particle has a first carrier core and a first coat layer whose main component is silicone resin, the first coat layer covering the first carrier core. The second carrier particle has a second carrier core and a second coat layer whose main component is silicone resin, the second coat layer being harder than the first coat layer and covering the second carrier core.

Abstract: A developer set includes a first developer as a two-component developer stored in a developing device from beginning of use of the developing device, and a second developer as a two-component developer stored in a replenishment container connected to the developing device, so as to be replenished to the developing device after starting use of the developing device. When a saturation magnetization of the carrier in the first developer is Sc, a resistance of the carrier in the first developer is R, and a content of the carrier with respect to toner of the second developer in the replenishment container is Cc, then 28<Sc×log10 R×Cc<120 is satisfied.

Abstract: When a surface potential of an opposing member is Vop (V), a DC voltage is Vdv (V), a particle size of carrier is Dc (m), a thickness of a coat layer is Tc (m), a space between a first surface and a second surface is Dg (m), and a maximum electric field applied to the coat layer is Emax (V/m), which is expressed by the following equation (1), then the following inequality (2) is satisfied. Emax = ? "\[LeftBracketingBar]" Vop - Vdv ? "\[RightBracketingBar]" × Dc / ( Tc × 2 × Dg ) ( 1 ) Emax ? 4.

Abstract: An image forming apparatus includes an image forming portion, a development voltage power supply, a current detection mechanism, and a control portion. The image forming portion includes an image carrying member having a photosensitive layer on its surface and a developing device that has a developer carrying member, opposite the image carrying member, carrying two-component developer containing magnetic carrier and toner. The development voltage power supply applies a development voltage at least containing a direct-current voltage to the developer carrying member. The current detection mechanism detects, with the development voltage applied to the developer carrying member, a development current between the developer carrying member and the image carrying member. The control portion estimates the amount of charge on toner based on a blank part current i.e., the development current passing between the developer carrying member and a non-image part of the image carrying member.

Abstract: An image forming apparatus includes an image forming portion, a development voltage power supply, a current detection mechanism, and a control portion. The image forming portion includes an image carrying member having a photosensitive layer on its surface and a developing device that has a developer carrying member carrying two-component developer containing magnetic carrier and toner, and attaches toner to an electrostatic latent image on the image carrying member, forming a toner image. The development voltage power supply applies a development voltage at least containing a direct-current voltage to the developer carrying member. The current detection mechanism detects, with the development voltage applied to the developer carrying member, a development current between the developer carrying member and the image carrying member. The control portion adjusts image density of the toner image according to a development current with a development condition changed by a plurality of levels.

Abstract: An image forming apparatus includes an image forming portion, a development voltage power supply, a current detection mechanism, and a control portion. The image forming portion includes an image carrying member having a photosensitive layer on its surface and a developing device that has a developer carrying member, opposite the image carrying member, carrying two-component developer containing magnetic carrier and toner, and that attaches toner to an electrostatic latent image on the image carrying member, forming a toner image. The development voltage power supply applies a development voltage at least containing a direct-current voltage to the developer carrying member. The current detection mechanism detects, with the development voltage applied to the developer carrying member, a development current between the developer carrying member and the image carrying member. The control portion adjusts image density of a halftone image according to a development current when the halftone image is formed.

Abstract: A magnet member is non-rotatably secured inside a developing sleeve, and includes a plurality of magnetic poles arranged along a rotation direction of the developing sleeve. The magnetic poles include a main pole facing the image carrying member, and a peeling pole that is disposed downstream of and adjacent to the main pole in the rotation direction of the developing sleeve and that peels off the developer carried on the developer carrying member. A magnetic-flux-density peak-position of the main pole is located below a horizontal line passing through a rotation center of the developing sleeve, and as viewed from an axial direction, an angle that a line extending from the magnetic-flux-density peak-position of the main pole to the rotation center of the developing sleeve forms with respect to the horizontal line passing through the rotation center of the developing sleeve is 40° or larger but 80° or smaller.

Abstract: An image forming apparatus includes an image carrying member, a charging device, an exposure device, a development device, and a development voltage power supply. The image carrying member has an amorphous silicon photosensitive layer formed on its surface. The development device includes a developer carrying member carrying two-component developer containing toner and carrier. The development voltage power supply applies to the developer carrying member a development voltage having an alternating-current voltage superposed on a direct-current voltage. When the blank part potential on the image carrying member is V0 [V], the direct-current voltage is Vdc [V], the peak-to-peak value of the alternating-current voltage Vac is Vpp [kV], and the gap between the image carrying member and the developer carrying member is Ds [mm], 10?V0?Vdc?90 and 1.2?Vpp/Ds?3.5 are fulfilled.

Abstract: A control portion stops driving a developer carrying member at the end of a development process for a preceding image to be printed on the last sheet of a preceding copy and starts driving the developer carrying member when performing a development process for a subsequent image to be printed on the first sheet of the subsequent copy. Regardless of the length of a development driving suspension period after stopping driving the developer carrying member following the end of the development process for the preceding image until starting driving the developer carrying member to perform the development process for the subsequent image, the control portion maintains suspension of the driving of the developer carrying member during the development driving suspension period.

Abstract: An image forming apparatus includes a developing device, a container, a toner replenishment device, a toner conveyance detection portion, and a control portion. The toner replenishment device includes a plurality of toner replenishment paths through which toner in the container is conveyed and replenished to the developing device. The toner conveyance detection portion detects a toner conveyance error in toner conveyance performed by using the plurality of toner replenishment paths. In a case where the toner conveyance detection portion has detected a toner conveyance error in one of the toner replenishment paths that is in use, the control portion switches to another one of the toner replenishment paths to convey the toner.

Abstract: An image forming apparatus includes a developing device, a container, a toner supplying device, and a control portion. The developing device supplies toner to an image carrying member. The container stores the toner supplied to the developing device. The toner supplying device transports the toner in the container to the developing device to supply the toner to it. The control portion senses toner emptiness in the container by using a plurality of emptiness sensing paths and uses different emptiness sensing conditions for the plurality of emptiness sensing paths.

Abstract: An image forming apparatus includes an image carrying member, a charging device, an exposure device, a development device, and a development voltage power supply. The image carrying member has an amorphous silicon photosensitive layer formed on its surface. The development device includes a developer carrying member carrying two-component developer containing toner and carrier. The development voltage power supply applies to the developer carrying member a development voltage having an alternating-current voltage superposed on a direct-current voltage. When the blank part potential on the image carrying member is V0 [V], the direct-current voltage is Vdc [V], the peak-to-peak value of the alternating-current voltage Vac is Vpp [kV], and the gap between the image carrying member and the developer carrying member is Ds [mm], 10?V0?Vdc?90 and 1.2?Vpp/Ds?3.5 are fulfilled.

Abstract: An image forming apparatus includes an image carrier, a charging device, an exposure device, a development device, and a development voltage power supply. The development device includes a development container storing a nonmagnetic one-component developer composed only of a toner, and a developer carrier on which a toner layer is formed on an outer circumferential surface thereof. The development voltage power supply applies a development voltage to the developer carrier. The image forming apparatus alternately forms white regions and exposed regions at a predetermined pitch repeatedly on a surface of the image carrier to form a solid image with an area ratio lower than 100%. Where V0 represents a white-region potential of the image carrier, VL represents an exposed-region potential of the image carrier, Vt represents a toner-layer potential, and Vd represents the development voltage, Vd?0.5*(V0?VL)+VL?Vt is fulfilled.

Abstract: An image forming apparatus includes an image carrying member, a charging device, an exposure device, a developing device, a development voltage power supply, and a control section. The developing device includes a development container which contains a non-magnetic one-component developer and a developer carrying member which includes a rotary shaft and a roller portion stacked on the outer circumferential surface of the rotary shaft, and the resistance value of the roller portion is 9 to 11 [Log ?], and when the amount of toner conveyed on the developer carrying member is Md [g/m2], the amount of toner adhered on the image carrying member in a solid image is Mp [g/m2], the peripheral speed of the developer carrying member and the image carrying member are Sd [mm/sec] and Sp [mm/sec], 0.8×Sd/Sp<Mp/Md and 0.8?Sd/Sp?1.2 are satisfied.

Abstract: An image forming apparatus includes an image carrier, a charging device, an exposure device, a development device, and a development voltage power supply. The development device includes a development container storing a nonmagnetic one-component developer composed only of a toner, and a developer carrier on which a toner layer is formed on an outer circumferential surface thereof. The development voltage power supply applies a development voltage to the developer carrier. The image forming apparatus alternately forms white regions and exposed regions at a predetermined pitch repeatedly on a surface of the image carrier to form a solid image with an area ratio lower than 100%. Where V0 represents a white-region potential of the image carrier, VL represents an exposed-region potential of the image carrier, Vt represents a toner-layer potential, and Vd represents the development voltage, Vd?0.5*(V0?VL)+VL?Vt is fulfilled.

Abstract: An image forming apparatus includes an image carrying member, a charging device, an exposure device, a developing device, a development voltage power supply, and a control section. The developing device includes a development container which contains a non-magnetic one-component developer and a developer carrying member which includes a rotary shaft and a roller portion stacked on the outer circumferential surface of the rotary shaft, and the resistance value of the roller portion is 9 to 11 [Log ?], and when the amount of toner conveyed on the developer carrying member is Md [g/m2], the amount of toner adhered on the image carrying member in a solid image is Mp [g/m2], the peripheral speed of the developer carrying member and the image carrying member are Sd [mm/sec] and Sp [mm/sec], 0.8×Sd/Sp<Mp/Md and 0.8?Sd/Sp?1.2 are satisfied.

Abstract: An image forming device includes photoconductor drum that rotates around axis and has drum circumferential face on which electrostatic latent image is formed, and developing unit that supplies developer to photoconductor drum thereby to manifest electrostatic latent image into developer image. The developing unit includes developing housing, developing roller supported by developing housing to be rotatable around axis, has first circumferential face that faces drum circumferential face and carries developer, and supplies carried developer to drum circumferential face, and restricting blade that contacts first circumferential face, and restricts amount of developer to be carried on first circumferential face, and first circumferential face has value of 4.