Embodiments of the invention relate to ink compositions suitable for applications in the printing industry, for example continuous inkjet printing, including ultra-high speed continuous inkjet printing. The ink compositions use volatile organic solvents, a colorant, and one or more binder resins including a resin that is a phenolic resole resin, wherein the ink composition is free of methanol, halogens, halogenated compounds and bisphenol-A. A phenolic resole resin of the ink composition preferably contains less than 0.1% by weight of free formaldehyde. The one or more binder resins including the phenolic resole resin may be present in an amount that is from about 5% to about 30% by weight of the ink composition.

Embodiments of the invention relate to ink compositions suitable for applications in the printing industry, for example continuous inkjet printing, including ultra-high speed continuous inkjet printing. The ink compositions use volatile organic solvents, a colorant, and one or more binder resins including a resin that is a phenolic resole resin, wherein the ink composition is free of methanol, halogens, halogenated compounds and bisphenol-A. A phenolic resole resin of the ink composition preferably contains less than 0.1% by weight of free formaldehyde. The one or more binder resins including the phenolic resole resin may be present in an amount that is from about 5% to about 30% by weight of the ink composition.

An image forming apparatus includes a controller circuitry configured to control the ink-jet module to form a density adjustive image pattern on one of the multiple sheets, detect a jam during continuous feeding, and then determine whether or not images, which are to be formed on one or more fed-and-unejected sheets, include the density adjustive image pattern, where the images include the density adjustive image pattern, determine whether or not the unejected sheet, on which the density adjustive image pattern is to be formed, has passed through a certain position of the sheet conveyer path, and control the ink-jet module, where the unejected sheet, on which the density adjustive image pattern is to be formed, has passed through the certain position, not to re-form the density adjustive image pattern and to re-form images on rest of the unejected sheets.

An image forming apparatus includes a controller circuitry configured to control the ink-jet module to form a density adjustive image pattern on one of the multiple sheets, detect a jam during continuous feeding, and then determine whether or not images, which are to be formed on one or more fed-and-unejected sheets, include the density adjustive image pattern, where the images include the density adjustive image pattern, determine whether or not the unejected sheet, on which the density adjustive image pattern is to be formed, has passed through a certain position of the sheet conveyer path, and control the ink-jet module, where the unejected sheet, on which the density adjustive image pattern is to be formed, has passed through the certain position, not to re-form the density adjustive image pattern and to re-form images on rest of the unejected sheets.

A method is provided for cleaning a print head, wherein the print head includes a cavity for the circulation of jets and at least one first spraying nozzle for projecting at least one cleaning fluid towards at least one inner portion of the cavity. The method includes the step of projecting, using the first spraying nozzle, several pulses of cleaning fluid towards the inside of the cavity.

A drop generator for a printing head of a continuous inkjet printer includes at least one ink feed conduit for feeding ink into a stimulation chamber, which has a quality factor Q lower than 2 and at least one resonant frequency f.sub.r; an actuator for stimulating a wall of said stimulation chamber; and at least one nozzle for ejecting a jet.

A method is provided for cleaning a print head, wherein the print head includes a cavity for the circulation of jets and at least one first spraying nozzle for projecting at least one cleaning fluid towards at least one inner portion of the cavity. The method includes the step of projecting, using the first spraying nozzle, several pulses of cleaning fluid towards the inside of the cavity.

A method is provided for cleaning a print head, wherein the print head includes a cavity for the circulation of jets and at least one first spraying nozzle for projecting at least one cleaning fluid towards at least one inner portion of the cavity. The method includes the step of projecting, using the first spraying nozzle, several pulses of cleaning fluid towards the inside of the cavity.

An image forming apparatus includes a conveyer belt that transports sheets, a platen plate that supports the conveyer belt to be slidable, a head holding unit that holds inkjet heads ejecting ink to sheets transported on the conveyer belt and being arrayed in a direction orthogonal to a transport direction of the conveyer belt, and a pair of gap adjustment units that have ends on one side being respectively attached to both ends of a lower surface of the head holding unit and ends on the other side being attached to an upper surface of the platen plate to adjust a gap between the lower surface of the head holding unit and the upper surface of the platen plate.

An image forming apparatus includes a conveyer belt that transports sheets, a platen plate that supports the conveyer belt to be slidable, a head holding unit that holds inkjet heads ejecting ink to sheets transported on the conveyer belt and being arrayed in a direction orthogonal to a transport direction of the conveyer belt, and a pair of gap adjustment units that have ends on one side being respectively attached to both ends of a lower surface of the head holding unit and ends on the other side being attached to an upper surface of the platen plate to adjust a gap between the lower surface of the head holding unit and the upper surface of the platen plate.