A printer includes at least a first printhead and a second printhead, each of which is operatively connected to a source of aqueous ink having a color that is different than the color of aqueous ink connected to the other printhead. A first source of infrared (IR) radiation is positioned between the first and second printheads and a second source of IR radiation follows the first and second printheads. The first source of IR radiation is tuned to heat color pigment particles in the aqueous ink connected to the first printhead only and the second source of IR radiation is tuned to heat color pigment particles in the aqueous ink connected to the second printhead only.

Provided are a position detection device, a printing apparatus equipped with the position detection device and a position detection method which make it possible to set an original point on a deviation-free appropriate position with no need of highly accurate adjustment of built-in positions of a linear encoder and an original point sensor.

In a case where a point that low-to-high switching of an output from a scale sensor is detected is set as a light transmission timing, a point that high-to-low switching of the output is detected is set as a light shielding timing and an output change point that an original point sensor detects is set as a detection timing, in a duration time D1 which lasts from the detection timing to a first light transmission timing which is the closest to the detection timing and a duration time D2 which lasts from the detection timing to a first light shielding timing which is the closest to the detection timing, when the duration time D1>the duration time D2, a position of a moving body which is obtained at a second light transmission timing is set as an original point and when the duration time D1<the duration time D2, the position of the moving body which is obtained at a second light shielding timing (the first light shielding timing) is set as the original point.

Provided are a position detection device, a printing apparatus equipped with the position detection device and a position detection method which make it possible to set an original point on a deviation-free appropriate position with no need of highly accurate adjustment of built-in positions of a linear encoder and an original point sensor.

In a case where a point that low-to-high switching of an output from a scale sensor is detected is set as a light transmission timing, a point that high-to-low switching of the output is detected is set as a light shielding timing and an output change point that an original point sensor detects is set as a detection timing, in a duration time D1 which lasts from the detection timing to a first light transmission timing which is the closest to the detection timing and a duration time D2 which lasts from the detection timing to a first light shielding timing which is the closest to the detection timing, when the duration time D1>the duration time D2, a position of a moving body which is obtained at a second light transmission timing is set as an original point and when the duration time D1<the duration time D2, the position of the moving body which is obtained at a second light shielding timing (the first light shielding timing) is set as the original point.

An ink jet method includes: a discharging step of discharging a radiation-curable ink jet composition onto a recording medium at an ink weight per dot of 22 ng/dot or less by using an ink jet head configured to discharge the radiation-curable ink jet composition and having a nozzle density of 600 npi or more; and an irradiating step of irradiating, with radiation, the radiation-curable ink jet composition attached to the recording medium. The radiation-curable ink jet composition contains polymerizable compounds including a monofunctional monomer and a multifunctional monomer. The monofunctional monomer includes a nitrogen-containing monofunctional monomer. The amount of the monofunctional monomer is 90 mass % or more relative to the total amount of the polymerizable compounds. The amount of the nitrogen-containing monofunctional monomer is from 1 to 15 mass % relative to the total amount of the polymerizable compounds.

An ink jet method includes: a discharging step of discharging a radiation-curable ink jet composition onto a recording medium at an ink weight per dot of 22 ng/dot or less by using an ink jet head configured to discharge the radiation-curable ink jet composition and having a nozzle density of 600 npi or more; and an irradiating step of irradiating, with radiation, the radiation-curable ink jet composition attached to the recording medium. The radiation-curable ink jet composition contains polymerizable compounds including a monofunctional monomer and a multifunctional monomer. The monofunctional monomer includes a nitrogen-containing monofunctional monomer. The amount of the monofunctional monomer is 90 mass % or more relative to the total amount of the polymerizable compounds. The amount of the nitrogen-containing monofunctional monomer is from 1 to 15 mass % relative to the total amount of the polymerizable compounds.

An ink jet method includes an ejecting step of ejecting a radiation-curable ink jet composition from an ink jet head and an irradiating step of irradiating the ejected radiation-curable ink jet composition with an ultraviolet ray at an irradiation intensity of 3 to 10 W/cm.sup.2 by using a light emitting diode. The radiation-curable ink jet composition contains monofunctional monomers including a nitrogen-containing monofunctional monomer. The amount of the nitrogen-containing monofunctional monomer relative to the total amount of the radiation-curable ink jet composition is 5 to 40 mass %.

An ink jet method includes an ejecting step of ejecting a radiation-curable ink jet composition from an ink jet head and an irradiating step of irradiating the ejected radiation-curable ink jet composition with an ultraviolet ray at an irradiation intensity of 3 to 10 W/cm.sup.2 by using a light emitting diode. The radiation-curable ink jet composition contains monofunctional monomers including a nitrogen-containing monofunctional monomer. The amount of the nitrogen-containing monofunctional monomer relative to the total amount of the radiation-curable ink jet composition is 5 to 40 mass %.

A radiation-curable ink jet composition comprises a polymerizable compound component including a monofunctional monomer component and a multifunctional monomer component. The content of the monofunctional monomer component is 87 mass % or more based on the total amount of the polymerizable compound component, the monofunctional monomer component includes a monofunctional acrylate containing a polycyclic hydrocarbon group, and the weighted average of the glass transition temperatures of homopolymers of the respective polymerizable compounds is 42 C. or more when the mass ratios of the contents of the respective polymerizable compounds are weighted.

A radiation-curable ink jet composition comprises a polymerizable compound component including a monofunctional monomer component and a multifunctional monomer component. The content of the monofunctional monomer component is 87 mass % or more based on the total amount of the polymerizable compound component, the monofunctional monomer component includes a monofunctional acrylate containing a polycyclic hydrocarbon group, and the weighted average of the glass transition temperatures of homopolymers of the respective polymerizable compounds is 42 C. or more when the mass ratios of the contents of the respective polymerizable compounds are weighted.

A radiation-curable ink jet composition comprises a polymerizable compound component including a monofunctional monomer component and a multifunctional monomer component. The content of the monofunctional monomer component is 87 mass % or more based on the polymerizable compound. The monofunctional monomer component includes a nitrogen-containing monofunctional monomer component, and the content of the nitrogen-containing monofunctional monomer component is 14 mass % or less based on total amount of the radiation-curable ink jet composition. The weighted average of the glass transition temperatures of homopolymers of the respective polymerizable compounds is 42 C. or more when the mass ratios of the contents of the respective polymerizable compounds are weighted.