A liquid circulation device includes a liquid chamber that stores a liquid that is to be supplied to a liquid discharge head. A pipeline through which the liquid can be circulated between the liquid chamber and the liquid discharge head is provided. A heater heats the liquid circulating in the pipeline. A first temperature sensor measures the temperature of the heater, and a second temperature sensor measures the temperature of the liquid in the pipeline. A controller controls the heating of the heater based on the liquid temperature measured by the second temperature sensor. The controller also monitors a change in the measured temperature of the heater over time and turns off the heating of the heater when the monitored change satisfies a predetermined stop condition.

Misalignment of printing positions between print heads associated with thermal expansion is reduced without increasing a data processing load. To this end, printing element substrates in a reference head and an adjustment target head are adjusted to a target temperature, and a liquid is circulated through the print element substrates. After thermal expansion of the reference head and the adjustment target head reaches a steady state, a first printing region being a printing region of the reference head and a second printing region being a printing region of the adjustment target head in a longitudinal direction are obtained from an image printed by using all printing elements. Then, used regions to be used for actual printing are set among the printing elements arranged on the reference head and the adjustment target head based on the first printing region and the second printing region.

A method for inkjet printing includes setting a target volume and a target concentration of ink discharged to a pixel, measuring a volume and a concentration of a liquid drop for each of nozzles, selecting first nozzle groups for achieving the target volume, from a volume pool of the liquid drop for each of the nozzles, selecting second nozzle groups for achieving the target concentration, from the first nozzle groups, selecting recipes by combining brightness trend lines, from the second nozzle groups, performing a printing simulation for each of the recipes to select a final recipe, and performing inkjet printing by using the final recipe.

In a control device, a controller sets an order condition using a plurality of sets of timing information and a plurality of index values stored in a memory. The plurality of index values is acquired from a recording device under a condition where a first cartridge is mounted in the recording device. The order condition requires that one of a latest index value and a current timing have reached corresponding one of a reference index value and a reference timing, and is set so that a second cartridge is delivered to a predetermined destination at a first timing at which the first cartridge is expected to be out of a printing agent while a tank of the recording device is expected to still accommodate the printing agent. The controller transmits an order command instructing to order the second cartridge to a relevant device after the order condition is satisfied.

In an image-recording device, a cartridge has a first chamber and an outlet. A mount body includes a tank, first and second sensors. The tank has an inlet, and a second chamber. The liquid in the first chamber flows into the second chamber via the outlet and the inlet. The first sensor outputs a first signal when a level of the liquid in the second chamber is higher than a first position, and outputs a second signal when the level is lower than the first position. The second sensor outputs a third signal when the level is higher than a second position higher than the first position, and outputs the fourth signal when the level is lower than the second position. A controller controls a notification device to issue a notification if a condition based on the first and second signals is satisfied.

A liquid remaining amount detecting mechanism includes a rotating member that is disposed in a storage chamber of a tank that stores a liquid, and a sensor. The rotating member is rotatable about a shaft and includes a float that receives buoyancy from the liquid, a detection target portion that is detectable by the sensor, and a through-hole into which the shaft is inserted. The sensor is disposed at a position facing a portion of a locus of the detection target portion when the rotating member is rotated. The liquid remaining amount detecting mechanism further includes a liquid pool portion, at least a portion of which is located between an outer peripheral surface of the shaft and an inner peripheral surface of the through-hole to hold the liquid.

A liquid ejection device includes a head having a nozzle, an element causing the nozzle to eject liquid, a reservoir configured to store the liquid to be supplied to the nozzle, and a controller. The controller is configured to change a drive signal to drive the element based on a quantity of the liquid stored in the reservoir.

An example printing fluid circulation circuit for a printing system comprises a first circuit port to supply printing fluid to, or receive printing fluid from, a first fluid port of a printhead and a second circuit port to supply printing fluid to, or receive printing fluid from, a second fluid port of a printhead. The printing fluid circulation circuit is to operate in a first mode to concurrently supply printing fluid from the first reservoir to the first circuit port and from the second circuit port to a second reservoir, and in a second mode to concurrently supply printing fluid from the first reservoir to the second circuit port and from the first circuit port to the second reservoir.

A fluid supply device includes a variable fluid volume to contain a supply of fluid and a variable gas volume to receive pressurized gas to pressurize the supply of fluid. A method of monitoring the fluid supply device may include controlling a gas pressure of the pressurized gas to feed the fluid from the fluid volume, the gas pressure varying in a plurality of pressurization cycles; monitoring a parameter of the pressurization cycles; and determining a change in fill state of the fluid volume as a function of the monitored parameter.

An ink-jet recording apparatus includes a recording unit, a scanning unit, an acquisition unit, and a determination unit. In the recording unit, a plurality of nozzles to apply ink is arrayed. The scanning unit is configured to perform relative scanning with the recording unit on a recording medium. The acquisition unit is configured to acquire input image data that includes a bar code including a plurality of black bars and a plurality of white bars and having a length in a first direction that is greater than a length in a second direction crossing the first direction. The determination unit is configured to determine, based on lengths of the plurality of white bars in the second direction, an amount of ink to be applied to a black bar adjacent to a corresponding white bar in the second direction.