Riso Kagaku Corporation

Hokkaido University

Asayo Nishimura

Yoshiyuki Okada

Hiroshi Sugitani

Masato Hirai

Hitoshi Arai

Akiko Hayashi

Toshihiro Bansyo

Tetsuo Hosoya

Akiko Yamamoto

A the non-aqueous pigment ink containing at least a non-aqueous solvent and a pigment that is self-dispersed in the solvent, wherein the self-dispersed pigment is treated with a compound represented by R1-X or R2-Y-R3, where X is any of &#x2014;SH, &#x2014;NCO, &#x2014;NH2 and &#x2014;NHR (where R is an alkyl group), Y is any of &#x2014;CO&#x2014;O&#x2014;O&#x2014;CO&#x2014; and &#x2014;CO&#x2014;O&#x2014;O&#x2014;, R1, R2 and R3 are alkyl groups with a carbon number of 8-22, the alkyl groups may be linear or branched, and R2 and R3 may be the same with or different from each other. Alternatively, the non-aqueous inkjet ink may contain at least a non-aqueous solvent and a pigment that is self-dispersed in the solvent, wherein a content of a polymer component in the ink is 20 mass % or less relative to the pigment, and the ink has a specific heat of 3.0 J/(g&#xb7;K) or less.

Non-aqueous pigment ink

An inkjet printerincludes an inkjet headwith nozzles for discharging ink, a pressurizer for pressurizing a route for ink supply to the inkjet head, a head driverfor driving the inkjet head, and a controlleroperable 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 driverto drive the inkjet headfor discharge operation in a maintenance service to the inkjet head

Inkjet printer and inkjet head maintenance method

A control unit is configured to form a print image on a recording medium by ejecting ink drops from nozzles of an ink head to the recording medium being conveyed on a conveyance route and sucked to the conveyance route by a negative pressure generated by a suction unit. The control unit is configured to control a level of suction power of sucking the recording medium to the conveyance route by the negative pressure in accordance with a level of a resolution of the print image in at least one of a main scanning direction or a sub scanning direction.

Inkjet recording machine

A duplex printing machineincludes an inkjet headwith a piezoelectric element set for vibrations to propel out droplets of aqueous ink, an inkbottlefor supplying aqueous inkto the inkjet head, a system of ink lineshaving a lower tank, a circulation pump, a filter, and an upper tank, a degasserhaving a degassing pumpfor degassing flux of aqueous inkbeing to be supplied to the inkjet head, and a controlleroperable to control the degassing pump, the controllerbeing adapted to operate, as a print time calculated from an image data set of a print job is equal to or greater than a prescribed value, for driving the degassing pumpto degas flux of aqueous ink

Printing machine

A drive pulse Pis turned on and off for an ink chamber to take in ink, exerting pressures thereon, and afterward, a drive pulse Pis turned on and off. This permits, in a course of variation in pressure of ink from a value at a positive pressure peak through a value at a normal pressure to negative pressures, a negative pressure peak C to be amplified for the ink chamber to take in ink with increased power. Further, following the drive pulse Ptuned off, a drive pulse Pis turned on to contract a volume in ink chamberB, producing pressures. Then, the drive pulse Pis turned off to enlarge the volume in ink chamberB, using back actions of produced pressures to have the ink chamberB quickly operate to take in much ink. This causes a subsequent drive pulse Pto be turned on at a hastened timing, and the drive pulse Pthus turned on makes a higher increase in pressure of ink in the ink chamberB, allowing a subsequent droplet of ink to be more quickly propelled out with an adequate pressure.

Droplet propelling device

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.

Printer and control method thereof

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.

Ink jet printer having ink maintenance system

An ink discharge unit includes a plurality of nozzles and corresponding ink propelling mechanisms for the nozzles, and configured to discharge ink through the nozzles in accordance with drive signals to drive the ink propelling mechanisms, an ink temperature sensor is adapted to measure a temperature of ink at the ink discharge unit, and a negative-pressure controller is configured to control negative pressures acting on menisci formed in vicinities of the nozzles by surface tension of ink at the ink discharge unit, wherein the negative-pressure controller is configured to work with a discharge of ink by the ink discharge unit, operating for a measured temperature of ink by the ink temperature sensor equal to or higher than a first reference, to control the negative pressures to a first value, and for a measured temperature of ink by the ink temperature sensor lower than the first reference, to control the negative pressures to a second value which is lower than the first value.

Image former

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. A drive signal generating unit is configured to generate a drive voltage signal including a prepulse to be applied to the set of the ink ejection elements for each block, based on data indicating a number of times of ejecting ink to each pixel; and a first storage unit is configured to store a drive signal adjustment value to adjust a set of a voltage value of the drive voltage signal and a width of the prepulse for each block. The drive signal generating unit generates the drive voltage signal for each block, based on the drive signal adjustment value for each block read out from the first storage unit.

Printing apparatus having line-type ink jet head and method of printing images by line-type ink jet head

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.

Ink circulation type inkjet printer

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.

Inkjet recording device

An 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 time is under the deterioration time of the ink, and drives the piezoelectric element of the ink jet head for a predetermined time to perform precursor microvibration immediately before the leading edge of the paper sheet reaches right under the ink jet head.

Ink jet head driver

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.

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Ibaraki-ken, Japan

Asayo Nishimura