Abstract: An agitation device includes: a first container configured to house a liquid; a second container configured to house the liquid transferred from the first container; a transfer agitation unit configured to selectively execute a transfer operation of transferring the liquid from the first container to the second container and an agitation operation of agitating the liquid in the second container by using a common drive source; and a controller configured to control the transfer agitation unit to alternately execute the transfer operation and the agitation operation upon transferring the liquid from the first container to the second container.

Abstract: A tank includes: a liquid container configured to store a liquid; an inlet opening through which the liquid flows into the liquid container; an outlet opening through which the liquid flows out from the liquid container; and a channel formation member arranged between the inlet opening and the outlet opening and configured to form channels. Widths of the channels are such that a channel at a position where stagnation of the liquid is more likely to occur has a larger width.

Abstract: An agitation device includes: a first container configured to house a liquid; a second container configured to house the liquid transferred from the first container; a transfer agitation unit configured to selectively execute a transfer operation of transferring the liquid from the first container to the second container and an agitation operation of agitating the liquid in the second container by using a common drive source; and a controller configured to control the transfer agitation unit to alternately execute the transfer operation and the agitation operation upon transferring the liquid from the first container to the second container.

Abstract: A tank includes: a liquid container configured to store a liquid; an inlet opening through which the liquid flows into the liquid container; an outlet opening through which the liquid flows out from the liquid container; and a channel formation member arranged between the inlet opening and the outlet opening and configured to form channels. Widths of the channels are such that a channel at a position where stagnation of the liquid is more likely to occur has a larger width.

Abstract: A controller is configured to control ink ejection timings of a plurality of head modules on a basis of a positional relation in a print width direction of a sheet between nozzles, covering a same pixel, of the plurality of head modules of different colors in each of a plurality of head module lines such that, among landing positions of inks from the nozzles of the different colors covering the same pixel, the landing position of the ink from the nozzle of at least one of the different colors is shifted in a transfer direction of the sheet from the landing positions of the inks from the nozzles of the other colors in at least one of the plurality of head module lines.

Abstract: An inkjet image forming apparatus includes ink heads, a drive voltage controller that adjusts density by controlling each drive voltage of the ink heads, a halftone processing controller that adjusts density by changing the number of ink droplets ejected from each nozzle of the ink heads, and a density adjustment controller that prints and scans a density adjustment pattern to calculate an adjustment value of each density level. The density adjustment controller adjusts density of a lowest density level so that the drive voltage controller controls each drive voltage based on the adjustment value of the lowest density level, and adjusts density of each density level other than the lowest density level so that the halftone processing controller changes the number of ink droplets based on the adjustment value of each density level other than the lowest density level and the adjustment result by the drive voltage controller.

Abstract: An inkjet image forming apparatus includes ink heads, a drive voltage controller that adjusts density by controlling each drive voltage of the ink heads, a halftone processing controller that adjusts density by changing the number of ink droplets ejected from each nozzle of the ink heads, and a density adjustment controller that prints and scans a density adjustment pattern to calculate an adjustment value of each density level. The density adjustment controller adjusts density of a lowest density level so that the drive voltage controller controls each drive voltage based on the adjustment value of the lowest density level, and adjusts density of each density level other than the lowest density level so that the halftone processing controller changes the number of ink droplets based on the adjustment value of each density level other than the lowest density level and the adjustment result by the drive voltage controller.

Abstract: An inkjet printer 1 includes an inkjet head 31 with nozzles for discharging ink, a pressurizer for pressurizing a route for ink supply to the inkjet head 31, a head driver 6 for driving the inkjet head 31, and a controller 8 operable for control the pressurizer to pressurize the route for a prescribed time to have fluxes of ink once spilt out of the nozzles and to render nozzles covered with spilt ink before use of the head driver 6 to drive the inkjet head 31 for discharge operation in a maintenance service to the inkjet head 31.

Abstract: A controller is configured to control ink ejection timings of a plurality of head modules on a basis of a positional relation in a print width direction of a sheet between nozzles, covering a same pixel, of the plurality of head modules of different colors in each of a plurality of head module lines such that, among landing positions of inks from the nozzles of the different colors covering the same pixel, the landing position of the ink from the nozzle of at least one of the different colors is shifted in a transfer direction of the sheet from the landing positions of the inks from the nozzles of the other colors in at least one of the plurality of head module lines.

Abstract: An inkjet printing apparatus includes two or more units. Each of the two or more units has a drive circuit, a nozzle row including a plurality of aligned nozzles configured to be driven by the drive circuit to eject ink, and an ink discharge passage configured to discharge a remainder of the ink supplied to the nozzles of the nozzle row from the nozzle row. The ink discharge passage of a first unit of the two or more units and the drive circuit of a second unit of the two or more units are thermally in contact with each other. The ink discharge passage of the second unit and the drive circuit of the first unit are thermally in contact with each other.

Abstract: An inkjet printing apparatus includes two or more units. Each of the two or more units has a drive circuit, a nozzle row including a plurality of aligned nozzles configured to be driven by the drive circuit to eject ink, and an ink discharge passage configured to discharge a remainder of the ink supplied to the nozzles of the nozzle row from the nozzle row. The ink discharge passage of a first unit of the two or more units and the drive circuit of a second unit of the two or more units are thermally in contact with each other. The ink discharge passage of the second unit and the drive circuit of the first unit are thermally in contact with each other.

Abstract: An inkjet printer employing an ink circulation system includes an ink temperature adjusting unit configured to adjust temperatures of circulating ink. The ink temperature adjusting unit includes: a first temperature-adjusting path for cooling ink connected to a first ink circulation path and a second ink circulation path; and a second temperature-adjusting path for heating ink connected to the second ink circulation path separately from the first temperature-adjusting path, connected to the first ink circulation path while joining the first temperature-adjusting path, and having a larger flow path resistance than that of the first temperature-adjusting path at least on a side near the first ink circulation path.

Abstract: An inkjet printing apparatus includes: an array of inkjet heads; a set of heating elements each in a corresponding one of the inkjet heads and each configured to heat ink; an ink circulation route configured to circulate ink through the inkjet heads; an inlet thermometer configured to measure, as first temperatures, ink temperatures of ink each flowing into a corresponding one of the inkjet heads; an outlet thermometer configured to measure, as second temperatures, ink temperatures of ink each flowing out of a corresponding one of the inkjet heads; a heating unit configured to heat ink being circulated; and a controller configured to work with a temperature difference between a first temperature and a second temperature for each same inkjet head to determine allocation of an available power for heating ink to the heating elements and the heating unit.

Abstract: A controller works with a measure of temperature of ink at a temperature sensor within a first temperature range to have an inkjet head propel out droplets of ink at a first discharge speed for formation of images, and with a measure of temperature of ink at the temperature sensor within a second temperature range lower than the first temperature range to have the inkjet head propel out droplets of ink at a second discharge speed greater than the first discharge speed for formation of images, and the controller determines that end regions of a frame of images to be formed in regions at transfer-longitudinal ends of a sheet to be transferred in a sheet transfer system have a print ratio within a prescribed range, to execute formation of images.

Abstract: An inkjet printer includes: an ink recycling path that recycles ink; an ink head 1 that performs printing by discharging the recycled ink; an ink supplying port that supplies ink from the ink recycling path to the inside of the ink head while controlling the pressure; and an ink discharging port that discharges ink from the inside of the ink head to the ink recycling path while controlling the pressure. When moving from a standby state where the recycling of ink in the ink recycling path remains stopped to a printing preparing state, an amount of ink smaller than an ink recycling amount during the printing is recycled for a predetermined time. Thereby, leakage of the ink and the inhalation of air bubbles from the nozzle are prevented by suppressing the change in pressure of the nozzle, and ink having high viscosity, which is the cause of these defects, is also removed when the recycling of ink starts.

Abstract: An inkjet printer 1 includes an inkjet head 31 with nozzles for discharging ink, a pressurizer for pressurizing a route for ink supply to the inkjet head 31, a head driver 6 for driving the inkjet head 31, and a controller 8 operable for control the pressurizer to pressurize the route for a prescribed time to have fluxes of ink once spilt out of the nozzles and to render nozzles covered with spilt ink before use of the head driver 6 to drive the inkjet head 31 for discharge operation in a maintenance service to the inkjet head 31.

Abstract: An ink jet printer is provided with an ink circulation route which includes an ink jet head, an ink supply tank and an ink collection tank. A measuring unit obtains a value indicative of the flow resistance measured when ink flows from the ink supply tank to the ink collection tank through the ink jet head. A control unit is operable to select one of maintenance operations on the basis of the value indicative of measured flow resistance. When the flow resistance value is lower than a predetermined value, the control unit selects the operation of circulating ink around the ink circulation route as a maintenance operation, and the maintenance unit does not perform the maintenance operation which consumes some amount of ink. This configuration makes it possible to perform maintenance in accordance with the ink viscosity by use of a simple structure.

Abstract: An inkjet printer employing an ink circulation system includes an ink temperature adjusting unit configured to adjust temperatures of circulating ink. The ink temperature adjusting unit includes: a first temperature-adjusting path for cooling ink connected to a first ink circulation path and a second ink circulation path; and a second temperature-adjusting path for heating ink connected to the second ink circulation path separately from the first temperature-adjusting path, connected to the first ink circulation path while joining the first temperature-adjusting path, and having a larger flow path resistance than that of the first temperature-adjusting path at least on a side near the first ink circulation path.

Abstract: In an inkjet printer where an ink recycling path for recycling ink is formed by connecting among an ink head, an upstream tank, and a downstream tank, the inkjet printer includes a temperature detecting unit that detects a temperature of recycling ink, a temperature changing unit that is installed in the ink recycled path and changes the temperature of the recycling ink so that the temperature of the recycling ink reaches a predetermined temperature, and an ink recycling amount changing unit that is installed at the upstream tank and changes an ink recycling amount according to the change in temperature of the recycling ink. Time required to make the temperature of the recycling ink reach the predetermined temperature can be shortened.

Abstract: An inkjet printing apparatus includes: an array of inkjet heads; a set of heating elements each in a corresponding one of the inkjet heads and each configured to heat ink; an ink circulation route configured to circulate ink through the inkjet heads; an inlet thermometer configured to measure, as first temperatures, ink temperatures of ink each flowing into a corresponding one of the inkjet heads; an outlet thermometer configured to measure, as second temperatures, ink temperatures of ink each flowing out of a corresponding one of the inkjet heads; a heating unit configured to heat ink being circulated; and a controller configured to work with a temperature difference between a first temperature and a second temperature for each same inkjet head to determine allocation of an available power for heating ink to the heating elements and the heating unit.