Abstract: An ink circulation type inkjet printer includes a maintenance controller configured to: (1) allow a maintenance mechanism to execute maintenance processing for a plurality of inkjet heads before a present printing job under three conditions that: (c1) an elapsed time from a last printing job to a present printing job is less than a first reference time; (c2) the present printing job requests for ejecting ink from unused nozzles of multiple nozzles of the plurality of inkjet heads in the last printing job; (c3) the elapsed time is more than a second reference time; (2) allow the ink circulation type inkjet printer to perform the present printing job without the maintenance processing for the plurality of inkjet heads when the elapsed time is less than the predetermined second reference time.

Abstract: An ink jet printer performs a print process by ejecting ink for each of a plurality of ink colors. When a predetermined first circulation time elapses after starting the ink circulation, an ink agitating operation drive signal generation unit applies an ink agitating operation drive signal to an ink ejecting unit set operable to eject an ink, which has a predetermined nature, for a first ink agitating operation time in a first period, and applies the ink agitating operation drive signal to an ink ejecting unit set operable to eject an ink, which has not the predetermined nature, for a second ink agitating operation time in a second period which is shorter than the first period. It is therefore possible to perform maintenance effectively in advance of starting the print process in accordance with the nature of ink.

Abstract: An inkjet recording device has an ink tank, a reservoir and an ink head, forms an ink supplying system by connecting with a path between the ink tank and the reservoir and between the reservoir and the ink head respectively, and forms a meniscus by generating a negative pressure on an ink discharging plane of the ink head by opening the reservoir to atmosphere. The inkjet recording device includes control electromagnetic valves to open or interrupt paths of the ink supplying system and valve switching control means for controlling opening/closing of the control electromagnetic valves, and controls the valve to be closed by the valve switching control means when the device vibrates. As a result, even if an ink liquid level in the reservoir changes when the device vibrates, transmission of this change to the meniscus of the ink discharging plane is prevented or suppressed.

Abstract: A printing apparatus is provided with a line-type ink jet head having a plurality of blocks on each of which a set of ink ejection elements are arranged. In the printing apparatus, a drive voltage signal is accompanied with a prepulse to be applied to each ink ejection element. Particularly, drive signal adjustment values are stored in association with each block. The drive voltage signal is generated for each set of ink ejection elements with reference to the drive signal adjustment values in association with the block on which the each set of ink ejection elements are arranged. By this configuration, it is possible to reduce the differential density between the image portion printed by the imperfect block having misaligned nozzles and the image portion printed by the normal block having nozzles arranged in their correct positions throughout the density range.

Abstract: An inkjet printer includes an inkjet head configured to perform printing on a printing sheet by use of ink. The inkjet printer includes: a heater configured to heat the ink; a thermometer configured to measure the temperature of the ink; and a controller configured to control the amount of electric power to be supplied to the heater and to control the inkjet head. In a case where the measured value of the ink temperature measured by the thermometer is in a range of a first reference temperature inclusive to a second reference temperature exclusive, the controller calculates a coverage rate of a page to be printed, and accordingly changes the amount of electric power to be supplied to the heater depending on the coverage rate thus calculated.

Abstract: An ink jet head driver, which is adapted to discharge ink drops of a number predetermined taking the maximum of discharged drops as a limit by each pixel data piece corresponding to plural pixels for constituting an image to a transported paper sheet at desired timing to form the image on the paper sheet in driving an ink jet head including a piezoelectric element for pressurizing ink by displacement of a shear mode and plural nozzles from which the ink is selectively discharged, the ink jet head driver including a control section that calculates a first head passing time required for the paper sheet from the leading edge to the tailing edge to pass the ink jet head, drives the piezoelectric element of the ink jet head for a predetermined time to perform precursor microvibration immediately before a leading edge of the paper sheet reaches right under the ink jet head and then drives the piezoelectric element according to the normal pixel data to form the image on the paper sheet when the first head passing ti

Abstract: A line-type inkjet recorder for printing a desired image onto paper by discharging ink from plural nozzles provided in a head part, the inkjet recorder includes: an image data processing part for converting image data to be printed into print data for each of the nozzles; a temperature detection part for detecting a temperature of the head part and outputting head temperature information based on the detected temperature; and a head control part for, based on states of a continuous non-discharge nozzle and a continuous discharge nozzle adjacent thereto included in the nozzles and extracted based on the head temperature information from the temperature detection part and the print data from the image data processing part, controlling frequencies of idle discharge from the continuous non-discharge nozzle and continuous discharge nozzle extracted.