53results about How to "Decrease in image density" patented technology

The present invention provides a toner containing at least a binder resin, a releasing agent, and a colorant, wherein the binder resin contains at least a polyester resin (A) having a softening point Tm(A) of 120° C. to 160° C., a polyester resin (B) having a softening point Tm(B) of 80° C. or more and less than 120° C. and a composite resin (C) containing a condensation polymerization monomer and an addition polymerization monomer, at least any one of the polyester resins (A) and (B) is a polyester resin prepared by condensation-polymerizing an alcohol component substantially composed of only aliphatic alcohol with a carboxylic acid component, and 65% or more of the alcohol component is 1,2-propanediol.

An image forming apparatus including: a latent electrostatic image bearing member, a charging unit, an exposing unit, a developing unit, a transfer unit, and a fixing unit, wherein the toner contains at least a binder resin and a colorant, the binder resin contains a polyester resin obtained by polycondensation of an alcohol component with a carboxylic acid component containing a rosin compound, the amount of the rosin compound contained in the carboxylic acid component is 5% by mass or more based on the total mass of the alcohol component and carboxylic acid component, and the amount of an abietic acid contained in the toner is 1% by mass or less.

The semiconductive roller according to the present invention includes a nonporous roller body made of a rubber composition containing styrene-butadiene rubber and epichlorohydrin rubber as rubber components.

A toner of the present invention comprises at least a binder resin comprising as a main component a polyester resin, a wax, and a colorant, in which in case of measuring a wettability of the toner with respect to a mixed solvent of methanol and water in terms of an optical transimittance at an optical wavelength of 780 nm, a methanol concentration of the mixed solvent is in a range of 45 to 65% by volume when an optical transmittance is 80% and 10%, respectively; a melt index (MI) is of 0.1 to 10 g / 10 min at a temperature of 125° C. and a load of 5 kg; the toner comparises a resin component insoluble to tetrahydrofuran (THF insoluble component) in an amount of 5 to 40% by mass based on a mass of the binder resin; and the toner comprises a THF soluble component having a main peak in a molecular weight region of 3,000 to 20,000, and has a proportion of a component having a molecular weight of 10,000 or less in the THF soluble component is 50% by mass or more, according to a chromatogram of the THF soluble component measured by gel permeation chromatography. According to the toner of the present invention, it is possible to control lowering of an image density after leaving under a high temperature and high humidity environment, and a decline in the image density due to a charge-rise phenomenon upon low rate printing. Further, the toner has excellent fixing property and high temperature offset characteristic, and occurring of the end-offset is controlled.

The present invention provides a toner containing base particles formed by emulsifying or dispersing, in an aqueous medium, a toner composition liquid which is obtained by dissolving or dispersing, in an organic solvent, at least a binder resin soluble in the organic solvent and a colorant masterbatch containing a colorant and a colorant dispersion resin, wherein the colorant dispersion resin is a resin having sparing solubility defined below: where the “sparing solubility” means that when 4 parts by mass of the colorant dispersion resin are added to and mixed with 10 parts by mass of the organic solvent, the mixture becomes white turbid at 25° C. or becomes a transparent solution once at 25° C. and then becomes white turbid within 12 hours.

An image forming apparatus and a process cartridge have high-durability and stably form high quality images under long-term use without reducing image density even when concentration of discharge products at the surface of an electrophotographic photoconductor becomes uneven in a discharge region of a charging unit. The apparatus employs an image forming method and has a corona discharge type charging unit discharging in a non-contact manner, the photoconductor placed to face the charging unit and the outermost surface layer thereof contains a filler and an amine compound with a specific structure, and an airflow adjusting device which carries air taken from the outside of the apparatus to the vicinity of the charging unit or the photoconductor so that ozone concentration and unevenness thereof are maintained at an average of 30 ppm or less and 15 ppm or less respectively at the surface of the photoconductor in the discharge region.

A toner is provided which is capable of preventing a decrease in a toner charge amount and thus preventing fog and a decrease in image density even in a case where images of low coverage are continuously printed or where a printing operation restarts immediately after long suspension of operation in an image forming apparatus. The toner contains coloring resin particles formed of a boron compound, a hinder resin, and a colorant, and an external additive of which a primary particle is adjusted to have a size of 16 nm or more and 30 nm or less and of which a volume resistivity is adjusted to 1×1012 Ω·cm or more and 5×1015 Ω·cm or less.

An image forming apparatus comprising a subsidiary charge roller and a development roller, wherein the diameter ratio I of the subsidiary charge roller to the development roller is in the range of 0.45 to 0.8. The subsidiary charge roller and the development roller can be arranged such that the linear velocity of the subsidiary charge roller Vs is larger than the linear velocity of the development roller Vd, and preferably the linear velocity ratio K of the subsidiary charge roller to the development roller is in the range of 1.01 to 1.06. Alternatively, the image forming apparatus can further comprises a compression section for applying a predetermined pressure to the opposite ends of the shaft of the subsidiary roller such that the subsidiary charge roller exerts a line pressure in the range of 8 to 100 gf / cm to the development roller. In addition, the subsidiary charge roller can further comprise a development roller gear coaxially formed on the development roller shaft and engaged with a subsidiary charge roller gear coaxially formed on the subsidiary charge roller shaft.

A developing device includes a developer container storing a developer, a developer supplying member supplying a toner stored in the developer container to an image bearing member, a voltage applying unit capable of applying a bias voltage to the developer supplying member, an image density detecting unit detecting a density of toner formed on the image bearing member, and a control unit correcting a toner concentration in the developer on the basis of a result of image density detection of a reference toner image formed on the image bearing member. The control unit is capable of executing a first toner concentration correction between printing operations and executing a second toner concentration correction between predetermined points during continuous printing.

An oil-based ink contains at least a dye and an organic solvent, wherein the dye is contained by an amount ranging from 0.1 to 20 mass % relative to the total amount of the ink, and the organic solvent contains a five-membered heterocyclic compound having a C═O bond or a phosphoric acid ester by an amount ranging from 50 to 99 mass % relative to the total amount of the ink.

An image forming apparatus including a subsidiary charge roller and a development roller, wherein the diameter ratio I of the subsidiary charge roller to the development roller is in the range of 0.45 to 0.8. The subsidiary charge roller and the development roller can be arranged such that the linear velocity of the subsidiary charge roller Vs is larger than the linear velocity of the development roller Vd, and preferably the linear velocity ratio K of the subsidiary charge roller to the development roller is in the range of 1.01 to 1.06. Alternatively, the image forming apparatus can further include a compression section for applying a predetermined pressure to the opposite ends of the shaft of the subsidiary roller and a development roller gear coaxially formed on the development roller shaft.

A development device including a developer container, a developer bearer, a magnetic field generator, a developer agitator to supply the developer to the developer bearer, and a developer regulator to adjust a layer thickness of the developer carried on the developer bearer. Multiple oval recesses oblique to the axial direction of the developer bearer are formed in the outer circumferential surface of the developer bearer and arranged in a circumferential direction and the axial direction thereof. An upstream inner wall of the recess in the rotational direction of the developer bearer applies a force to the developer as the developer bearer rotates, and an angle between a long axis of the recess and the axial direction is set so that the force applied by the upstream inner wall of the recess has a component in a direction substantially identical to the developer conveyance direction of the developer agitator.

An image forming apparatus includes an image bearing member for bearing a developer image; a developing device including a developer carrying member for forming the developer image on the image bearing member; a fixing device for fixing the developer image on a sheet material, on which the developer image has been transferred, by heating the sheet material; a memory medium for storing an operation hysteresis value, of the developing device, which varies depending on a state of an operation of the developing device from start of the operation; and a controller for controlling a temperature of the fixing device. The controller controls, when the operation hysteresis value stored in the memory medium reaches a preset threshold, the temperature of the fixing device so as to be lower than that before the operation hysteresis value reaches the preset threshold.

An image forming apparatus including: image forming stations each including: a photosensitive drum; a charger configured to charge the drum; a transfer device configured to transfer a developer image on the drum onto an intermediate transfer member; and a cleaner configured to remove developer from the drum; an exposure device configured to expose the drum to form a latent image; the intermediate transfer member; a memory storing information on the drum; and a controller configured to control at least one of the charger, transfer device, and exposure device in the station based on the information in the memory to provide a predetermined potential difference between the drum and the transfer device to form an electric field therebetween in a reverse direction to that in an image formation in order to move the developer from the intermediate transfer member to the drum to collect the developer by the cleaner.

A carrier coated with a resin for an electrophotographic developer in which a carrier particle surface is coated with the resin and the coating resin contains a lithium salt, and an electrophotographic developer using the carrier coated with the resin.

An image forming apparatus includes: a developing device; a toner supply device; and a toner supply detecting sensor; and a toner concentration controller that directs toner supply. The toner concentration controller includes: a memory that stores the difference between the outputs from toner supply detecting sensor before and after toner supply; a toner supply quantity determinater that determines that the amount of toner remaining in the toner supply device is low and the amount of toner supply is low when the output difference or output ratio of the sensor is lower than a supply reference value; and an image quality adjustment controller that shortens the interval of time between adjustment of electrical potential on toner concentration correction in the above case.

A yellow toner comprising colored resin particles containing a binder resin and a yellow colorant, wherein the yellow colorant is a compound represented by a structural formula (1):wherein R1, R2, R3 and R4 are, independently of one another, a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms, and the average circularity of the colored resin particles is 0.970 to 0.995.

A toner of the present invention comprises at least a binder resin comprising as a main component a polyester resin, a wax, and a colorant, in which in case of measuring a wettability of the toner with respect to a mixed solvent of methanol and water in terms of an optical transimittance at an optical wavelength of 780 nm, a methanol concentration of the mixed solvent is in a range of 45 to 65% by volume when an optical transmittance is 80% and 10%, respectively; a melt index (MI) is of 0.1 to 10 g / 10 min at a temperature of 125° C. and a load of 5 kg; the toner comparises a resin component insoluble to tetrahydrofuran (THF insoluble component) in an amount of 5 to 40% by mass based on a mass of the binder resin; and the toner comprises a THF soluble component having a main peak in a molecular weight region of 3,000 to 20,000, and has a proportion of a component having a molecular weight of 10,000 or less in the THF soluble component is 50% by mass or more, according to a chromatogram of the THF soluble component measured by gel permeation chromatography. According to the toner of the present invention, it is possible to control lowering of an image density after leaving under a high temperature and high humidity environment, and a decline in the image density due to a charge-rise phenomenon upon low rate printing. Further, the toner has excellent fixing property and high temperature offset characteristic, and occurring of the end-offset is controlled.

The present invention provides a toner containing at least a binder resin, a releasing agent, and a colorant, wherein the binder resin contains at least a polyester resin (A) having a softening point Tm (A) of 120° C. to 160° C., a polyester resin (B) having a softening point Tm (B) of 80° C. or more and less than 120° C. and a composite resin (C) containing a condensation polymerization monomer and an addition polymerization monomer, at least any one of the polyester resins (A) and (B) is a polyester resin prepared by condensation-polymerizing an alcohol component substantially composed of only aliphatic alcohol with a carboxylic acid component, and 65% or more of the alcohol component is 1,2-propanediol.

An inkjet recording method comprising ejecting an ink composition comprising a dispersion medium and charged particles containing at least a colorant by utilizing an electrostatic field, wherein the method comprises preparing as the ink composition, an initial feeding ink composition and a replenishing ink composition in which solid content concentration is controlled higher than solid content concentration of the initial feeding ink composition, and replenishing the replenishing ink composition in order to compensate decrease in concentration of the charged particles due to ejection of the initial feeding ink composition.

An inkjet recording method comprising ejecting an ink composition comprising a dispersion medium and charged particles containing at least a colorant by utilizing an electrostatic field, wherein the method comprises preparing as the ink composition, an initial feeding ink composition and a replenishing ink composition in which solid content concentration is controlled higher than solid content concentration of the initial feeding ink composition, and replenishing the replenishing ink composition in order to compensate decrease in concentration of the charged particles due to ejection of the initial feeding ink composition.

An electrophotographic photoreceptor comprising a support and a photosensitive layer is disclosed. The photosensitive layer contains a mixture of compounds represented by Formula (1) having different n and (Rp+Rs) is not more than 99%, wherein Rp is a ratio of a component having the maximum content in the mixture and Rs is a ratio of a component having the content next to the maximum content in percent.X—(CTM-group)n—Y  (1)In the formula, CTM-group is a charge transfer group; X and Y are each a hydrogen atom, a halogen atom or a mono-valent organic group; and n is an integer of from 0 to 10, provided that n is an integer of from 1 to 10 when both X and Y are hydrogen atom or a halogen atom. A processing cartridge comprising the electrophotographic photoreceptor is also disclosed.

An image forming apparatus and a process cartridge have high-durability and stably form high quality images under long-term use without reducing image density even when concentration of discharge products at the surface of an electrophotographic photoconductor becomes uneven in a discharge region of a charging unit. The apparatus employs an image forming method and has a corona discharge type charging unit discharging in a non-contact manner, the photoconductor placed to face the charging unit and the outermost surface layer thereof contains a filler and an amine compound with a specific structure, and an airflow adjusting device which carries air taken from the outside of the apparatus to the vicinity of the charging unit or the photoconductor so that ozone concentration and unevenness thereof are maintained at an average of 30 ppm or less and 15 ppm or less respectively at the surface of the photoconductor in the discharge region.

A method for printing an image with authentication features, including: printing a media treatment material onto a print medium in accordance with a pattern of predefined authentication features, and printing one or more visible printing materials onto the print medium in accordance with an image pattern, thereby providing a printed visible image. The media treatment material alters an interaction between the visible printing materials and the print medium so that characteristics of the interaction, such as printing material penetration characteristics, are different in image regions where the media treatment material was printed than in image regions where the media treatment material was not printed. The difference in the characteristics of the interaction between the one or more visible printing materials and the print medium causes the pattern of authentication features to be detectable.

The present invention relates to an image forming method wherein the surface of an electrophotographic photoreceptor contains a compound having an unsaturated double bond, a toner for electrostatic latent image development has a binder resin obtained by polymerizing a polymerizable monomer having a vinyl double bond, has at least one kind of metal oxide particles and / or metal nitride particles on the surface of the toner and has a shape factor SF1 of 110 to 140, and the storage of elastic modulus at 160° C. (G′(160)) of the toner for electrostatic latent image development is in a predetermined range.

A toner comprising an external additive and a toner particle including a binder resin, a colorant and inorganic fine particles A, wherein the external additive contains an external additive B, a number average particle diameter of primary particles of the external additive B is 30 to 200 nm, an adhesion index of the external additive B to the toner particle is 0.00 to 3.00, a number average particle diameter of primary particles of the inorganic fine particles A is greater than that of the external additive B, and in SEM observations of the toner under specific condition, the number of particles (Na) of the external additive B in a 2 μm square region of the toner surface and the number of particles (Nb) of the external additive B observed in a state of overlapping with the inorganic fine particles A in the region satisfy Nb / Na of 0.20 or more.