A heating device, an image forming apparatus, and a liquid discharge apparatus. The heating device includes a heating roller having heat sources inside to heat a sheet. The heat sources include three or more first heat sources having a same distribution of thermal intensity and a second heat source having a distribution of thermal intensity different from the distribution of the thermal intensity of the first heat sources, and the second heat source is disposed inside a polygon whose vertices are the first heat sources when viewed from one end of the heating roller in a longitudinal direction of the heating roller. The image forming apparatus includes an image forming device to form an image on a sheet, and the heating device to heat the sheet. The liquid discharge apparatus includes a liquid discharge device to discharge liquid onto a sheet, and the heating device to heat the sheet.

A printer that performs printing on a medium by an inkjet scheme includes an inkjet head, for ejecting droplets of an ink containing a solvent to be evaporated to fix the ink on the medium; and an ultraviolet light source that irradiates the ink with an ultraviolet light. The ink contains a colorant, the solvent, an exothermic polymerizable substance, and a polymerization initiator. The colorant develops a color of the ink. The exothermic polymerizable substance causes a polymerization reaction to generate heat. The polymerization initiator starts the polymerization reaction of the exothermic polymerizable substance in response to irradiation with ultraviolet light. The ultraviolet light source irradiates the ink adhered to the medium with ultraviolet light to make the exothermic polymerizable substance cause the polymerization reaction. Thus, the solvent in the ink is evaporated by the heat generated by the polymerization reaction to fix the ink on the medium.

An inkjet printer includes a first ink head to eject a first ink, and a second ink head to eject a second ink. A generator generates dot groups including at least a first dot group and a second dot group including ink dots of the second ink. The dot groups include all the ink dots of the second ink. A first printing controller forms, on a recording medium, a first printing layer of the first ink and the first dot group. A second printing controller forms a second printing layer of the second dot group, above or below the first printing layer.

An inkjet recording apparatus has a recording head, a thermal head, and a heat control portion. The recording head has an ink discharge surface. The thermal head is arranged opposite the ink discharge surface across a recording medium conveying passage and heats a recording medium. In the thermal head, a plurality of element arrays each formed of a plurality of heating elements arrayed in the recording medium conveying direction are provided in the width direction. The heat control portion makes at least part of the heating elements in the element arrays that correspond to the ink discharge ports that discharge ink generate heat.

An inkjet recording apparatus has a recording head, a thermal head, and a heat control portion. The recording head has an ink discharge surface. The thermal head is arranged opposite the ink discharge surface across a recording medium conveyance passage, and heats the recording medium. The thermal head is provided with a plurality of element arrays in the width direction, the element arrays each having a plurality of heating elements arrayed in the recording medium conveyance direction. The heat control portion makes generate heat at least some heating elements in the element arrays corresponding to the ink discharge ports through which ink is discharged.

There are provided an aqueous ink composition containing a polyolefin wax; a resin dispersion; water; and a surfactant A, in which a content of one kind or more of the surfactants A, which are surfactants having a molecular weight of less than 10,000 and which are selected from the group consisting of an ionic surfactant and a nonionic surfactant, the nonionic surfactant being selected from the group consisting of ethers of polyalkylene oxide, higher aliphatic acid esters, and higher aliphatic amides, is 7 parts by mass or less when a total content of the resin of the resin dispersion and the polyolefin wax is 100 parts by mass, and the aqueous ink composition is used in a recording method including attaching a reaction liquid, which contains an aggregating agent for aggregating components of an aqueous ink composition, to a recording medium.

A printing apparatus for performing printing on a medium includes a temperature sensor configured to detect temperature and a control unit configured to, in a case where an operation mode of the printing apparatus is a first mode, allow the temperature sensor to detect temperature of heat emitted by an external heater, and execute processing in relation to an adjustment of the external heater based on the detected temperature. The external heater is externally installed and is configured to heat the medium.

A printer includes a media feeder to feeding media in a feed direction, a print head to eject droplets of ink onto the media, heaters to heat the media, and a controller to perform a printing operation corresponding to received print data by causing the media feeder to feed the media heated by the heaters and causing the print head to eject the droplets of ink onto the media based on the print data, the controller being configured or programmed to move the media and/or the heaters during the print idle time before performing the printing operation.

An ink jet recording method includes heating a recording medium, and attaching an aqueous ink composition to the heated recording medium by ejecting the aqueous ink composition through a nozzle. The aqueous ink composition contains water, a solvent, and resin particles. In the attaching step, a temperature difference between a temperature of the nozzle and a surface temperature of the heated recording medium is 4 to 8 C. The resin particles include particular resin particles formed from a resin whose decrease rate of absorbance of light having a wavelength of 400 nm is 15% or smaller in 1 hour at 40 C. and 10% or larger in 1 hour at 80 C. in a liquid mixture containing the solvent contained in the aqueous ink composition and the particular resin particles such that a resin solid component of the liquid mixture is 0.5% by mass.

A recording method includes applying an ink composition onto a recording medium, primarily drying the recording medium during the application of the ink composition, transporting the recording medium applied the ink composition to a secondary drying device, and secondarily drying the recording medium with the secondary drying device. The variation in surface temperature of the recording medium from the primary drying temperature (T1) to the lowest temperature and the variation in surface temperature of the recording medium from T1 to the highest temperature, in the period from completion of the application of the ink composition to completion of the secondary drying are 40% or more and 370% or less, respectively, relative to T1. The surface temperature of the recording medium is increased to the secondary drying temperature at an average rate of 7 C./s or less after the completion of the application of the ink composition.