A developing device includes a frame, a cylindrical developer carrying member rotatably supported by the frame and configured to carry a developer containing toner particles, and a regulating member fixed to the frame at one end thereof and including a contact portion which contacts the developer carrying member at the other end of the regulating member and which forms a contact nip between the regulating member and the developer carrying member. When a position of the contact portion where a maximum of a pressure distribution of the contact portion to the developer carrying member with respect to a rotational direction of the developer carrying member is indicated is a reference position, the contact portion includes a first surface portion positioned upstream of the reference position and a second surface portion positioned downstream of the reference position with respect to the rotational direction.

Toners are provided which may comprise toner particles, a colorant, and optionally, a wax, wherein the toner particles comprise a resin comprising a polymerization product of reactants comprising a dioxane/dioxolane monomer and a vinyl co-monomer, wherein the dioxane/dioxolane monomer is an ester of (meth)acrylic acid with an alcohol comprising a dioxane moiety, an ester of (meth)acrylic acid with an alcohol comprising a dioxolane moiety, or both.

A toner comprising: a toner particle comprising a binder resin and boric acid; and an external additive A having a primary particle major diameter of 80 to 200 nm, wherein in ATR-IR analysis of the toner particle in an ATR method using germanium as an ATR crystal, a peak corresponding to boric acid is detected, the average value of a shape factor SF-1 of the external additive A is 105 to 250, and the average value of a shape factor SF-2 of the external additive A is 102 to 250.

An image forming apparatus forms an image on a recording medium using first to fourth toners, and includes an intermediate transfer target; a primary transfer unit that transfers a first toner image, a second toner image, a third toner image, and a fourth toner image to the intermediate transfer target in stated order; and a secondary transfer unit that collectively transfers the first to fourth toner images onto the recording medium. The first toner image, the second toner image, the third toner image, and the fourth toner image include the first toner, the second toner, the third toner, and the fourth toner, respectively. The first to fourth toners each include toner particles. The toner particles each include a toner mother particle and an external additive attached to the surface of the toner mother particle. The external additive includes fluororesin particles and silica particles.

A toner comprising a toner particle, and an external additive on a surface of the toner particle, wherein the external additive comprises an agglomerate of fine silica particles surface-treated with silicone oil; when a number-average particle diameter of the agglomerate of the fine silica particles is defined as Rb, the Rb is 12 to 80 nm; when an integrated value of a D unit is defined as A, which obtained when an integrated value of a Q unit is set to 100 in a CP/MAS measurement in a .sup.29Si-solid-state NMR of the fine silica particles, the A is 120 to 300, and the agglomerate of the fine silica particles has a coefficient of variation of particle diameters of 1.00 to 3.00, based on a number of the agglomerate of the fine silica particles.

A toner includes: toner base particles including a binder resin, a colorant, an inorganic filler, and a release agent; and an external additive. An average circularity of the toner is 0.974 or more but 0.985 or less. A surface roughness parameter Sz of a surface of the toner is 200 nm or more but 500 nm or less, the surface roughness parameter Sz being measured with an atomic force microscope (AFM).

A toner having a toner particle containing a binder resin, an amorphous polyester, and a colorant, wherein a softening point of the toner is at least 110° C. and not more than 140° C.; an integrated value f1 for stress of the toner is not more than 10 g.Math.m/sec, as measured using a tack tester, with a temperature for a probe end being 150° C. and a press holding time being 0.01 seconds; and an integrated value f2 for stress of the toner is at least 30 g.Math.m/sec, as measured using a tack tester, with a temperature for a probe end being 150° C. and a press holding time being 0.1 seconds.

A developing device includes a frame, a cylindrical developer carrying member rotatably supported by the frame and configured to carry a developer containing toner particles, and a regulating member fixed to the frame at one end thereof and including a contact portion which contacts the developer carrying member at the other end of the regulating member and which forms a contact nip between the regulating member and the developer carrying member. When a position of the contact portion where a maximum of a pressure distribution of the contact portion to the developer carrying member with respect to a rotational direction of the developer carrying member is indicated is a reference position, the contact portion includes a first surface portion positioned upstream of the reference position and a second surface portion positioned downstream of the reference position with respect to the rotational direction.

A lustrous developer according to an embodiment may include: a metallic pigment; and a binder resin. The lustrous developer includes small diameter particles smaller than a volume median diameter of the metallic pigment. A ratio of a volume of particles other than the small diameter particles in the lustrous developer to a volume of the entire lustrous developer is 90.297% or more and 99.314% or less. The volume median diameter of the metallic pigment is 5.91 μm or less.

Toners are provided which may comprise toner particles, a colorant, and optionally, a wax, wherein the toner particles comprise a resin comprising a polymerization product of reactants comprising a dioxane/dioxolane monomer and a vinyl co-monomer, wherein the dioxane/dioxolane monomer is an ester of (meth)acrylic acid with an alcohol comprising a dioxane moiety, an ester of (meth)acrylic acid with an alcohol comprising a dioxolane moiety, or both.