An image forming apparatus includes a main body, endless belt, photosensitive drums, setting unit, contacting/separating mechanism, transmitting mechanism, and coupling members. The photosensitive drums are disposed in confrontation with the endless belt and are arranged in a first direction. Each photosensitive drum has an axis extending in a second direction perpendicular to the first direction. The setting unit sets the image forming apparatus to a monochrome mode or color mode. The contacting/separating mechanism controls at least one photosensitive drum to contact or separate from the endless in accordance with the set mode. The transmitting mechanism selectively transmits drive power to photosensitive drums. Each coupling member is selectively coupled to the corresponding photosensitive drum and has a coupling axis extending in the second direction. Each coupling member is uncoupled from the corresponding photosensitive drum when the contacting/separating mechanism controls the corresponding photosensitive drum to separate from the endless belt.

An image forming apparatus, having first, second, and third photosensitive drums, a first developing cartridge including a first developing roller, a second developing cartridge including a second developing roller, a third developing cartridge including a third developing roller, an exposure device, a conveyer, and a moving mechanism, is provided. The first developing roller, the second developing roller, and the third developing roller are arranged in the recited order from upstream to downstream in a moving direction for the sheet to be conveyed. When the second developing roller is at the separated position thereof, the second developing cartridge coincides with a light path of the laser beam for scanning the first photosensitive drum. When the third developing roller is at the separated position thereof, the third developing cartridge coincides with a light path of the laser beam for scanning the second photosensitive drum.

An image forming apparatus controls a first image forming unit and a second image forming unit to form a plurality of pattern images. The plurality of pattern images includes a first pattern image formed by the first image forming unit, a second pattern image formed by the second image forming unit, a plurality of third pattern images that are formed by the first image forming unit and have different tones from one another, and a plurality of fourth pattern images that are formed by the second image forming unit and have different tones from one another. The image forming apparatus obtains data that has been output from a sensor and is related to the plurality of pattern images, and generates the conversion condition based on the data.

An image forming apparatus includes a first toner image forming unit, a second toner image forming unit, and a transfer section. The first toner image forming unit forms a first toner image with use of a first toner. The first toner has a complex viscosity that falls within a range from 625 Pascal-seconds to 3860 Pascal-seconds, both inclusive, at a temperature of 100 degrees centigrade. The second toner image forming unit forms a second toner image with use of a second toner. The transfer section transfers the first toner image onto a print medium, and transfers the second toner image onto the print medium in a region that overlaps a portion or all of a region where the first toner image has been transferred. The print medium includes a polymer compound.

A toner container used in an image forming apparatus including an exposure unit with a light emitting diode light source includes a container body, and a cyan toner stored in the container body. A lightness L*, a hue a*, and a hue b* of the cyan toner in a powder state satisfy
26.94L*34.84,
5.13a*3.83, and
47.47b*36.78.

An image forming apparatus includes an image bearing member, a developing member, a controller configured to carry out switching control between a first state in which the developing member is caused to act on the image bearing member and a second state in which the developing member is not caused to act on the image bearing member, a transfer member, and a detector configured to read density information of the recording material. The controller detects a fog density on the basis of a difference intensity information between a fog non-occurrence region of a non-image region of the recording material in the second state and a fog occurable region of the non-image region of the recording material in the first state.

A toner container used in an image forming apparatus including an exposure unit with a light emitting diode light source. The toner container including a container body, and a cyan toner stored in the container body. The cyan toner includes a binder resin, at least one pigment, a charge control agent, and an external additive. The at least one pigment includes at least Pigment Blue. A lightness L*, a hue a*, and a hue b* of the cyan toner in a powder state satisfy: 30.04L*33.68, 1.75a*0.71, and 47.47b*45.08.

A printing system is disclosed which comprises a writing module, and a member having an imaging surface configured to carry a polymer and movable relative to the writing module. The writing module is configured to direct onto the imaging surface a plurality of individually controllable light beams that are spaced from one another in a direction transverse to the direction of movement of the imaging surface, incidence of a light beam on a spot on the imaging surface serving to soften or liquefy the polymer carried by the imaging surface at the spot. The polymer softened or liquefied at the spot can transfer to a substrate or serve as an adhesive on the imaging surface. The writing module comprises a plurality of integrated electronic modules each having an array of individually controllable light sources, each light source producing a respective one of the light beams. In the invention, each light source comprises at least two Vertical-Cavity Surface-Emitting Laser (VCSEL) light-emitting semiconductor junctions connected in series with one another and configured to direct light onto the imaging surface at the same spot as one another.

An image forming apparatus, having first, second, and third photosensitive drums, a first developing cartridge including a first developing roller, a second developing cartridge including a second developing roller, a third developing cartridge including a third developing roller, an exposure device, a conveyer, and a moving mechanism, is provided. The first developing roller, the second developing roller, and the third developing roller are arranged in the recited order from upstream to downstream in a moving direction for the sheet to be conveyed. When the second developing roller is at the separated position thereof, the second developing cartridge coincides with a light path of the laser beam for scanning the first photosensitive drum. When the third developing roller is at the separated position thereof, the third developing cartridge coincides with a light path of the laser beam for scanning the second photosensitive drum.

An image forming apparatus includes a main body, endless belt, photosensitive drums, setting unit, contacting/separating mechanism, transmitting mechanism, and coupling members. The photosensitive drums are disposed in confrontation with the endless belt and are arranged in a first direction. Each photosensitive drum has an axis extending in a second direction perpendicular to the first direction. The setting unit sets the image forming apparatus to a monochrome mode or color mode. The contacting/separating mechanism controls at least one photosensitive drum to contact or separate from the endless in accordance with the set mode. The transmitting mechanism selectively transmits drive power to photosensitive drums. Each coupling member is selectively coupled to the corresponding photosensitive drum and has a coupling axis extending in the second direction. Each coupling member is uncoupled from the corresponding photosensitive drum when the contacting/separating mechanism controls the corresponding photosensitive drum to separate from the endless belt.