Liquid-jetting apparatus and method of driving the same

A liquid-jetting apparatus comprising:

• a liquid-jetting head provided with nozzle openings and capable of jetting liquid particles through the nozzle openings;
• a recovering unit to recover from a state of thickened in a liquid in the nozzle openings, the recovering unit comprising a flushing unit that carries out a flushing operation to jet the liquid in the nozzle openings in minute liquid particles, the minute liquid particle having a weight of 10 ng or below and being jetted at a jetting speed of 8 m/s or above,
• wherein the liquid-jetting head has pressure chambers respectively communicating with the nozzle openings and containing the liquid, and pressure generating means to vary pressure in the pressure chambers to jet liquid particles through the nozzle openings,
• wherein the flushing unit has a driving unit to drive the pressure generating means for the flushing operation,
• wherein the pressure generating means comprises piezoelectric members capable of deforming the pressure chambers to jet liquid particles through the nozzle openings,
• wherein the driving unit outputs a driving signal to the piezoelectric member, and
• wherein the driving signal given by the driving unit to the piezoelectric member comprises:
• a first voltage-raising part to apply a voltage for expanding the pressure chamber so that the pressure in the pressure chamber is reduced to the piezoelectric member,
• a first voltage holding part to apply a voltage for maintaining the pressure chamber at a reduced pressure to the piezoelectric member,
• a first voltage-reducing part to apply a voltage for contracting the pressure chamber to raise the pressure in the pressure chamber to a slightly reduced pressure to the piezoelectric member,
• a second voltage holding part to apply a voltage for maintaining the pressure chamber at the slightly reduced pressure to the piezoelectric member, and
• a second voltage-reducing part to apply a voltage for setting the pressure chamber in its original state to the piezoelectric member.

A liquid-jetting apparatus comprising:

• a liquid-jetting head provided with nozzle openings and capable of jetting liquid particles through the nozzle openings;
• a recovering unit to recover from a state of thickened liquid in the nozzle openings, the recovering unit comprising a flushing unit that carries out a flushing operation to jet the liquid in the nozzle openings in minute liquid particles, the minute liquid particle having a weight of 10 ng or below and being jetted at a jetting speed of 8 m/s or above, the flushing unit is capable of carrying out the flushing operation selectively in a first flushing mode or a second flushing mode;
• a head moving mechanism to move the liquid-jetting head in a scanning direction;
• a capping mechanism disposed in a head-moving range in which the liquid-jetting head is able to move and capable of covering the nozzle openings;
• a timer for measuring a time elapsed after the nozzle openings have been covered with the capping mechanism;
• and
• a mode control unit to selectively determine the mode of the flushing operation based on the time measured by the timer,
• wherein the flushing operation of the first mode jets a minute liquid particle having a weight of 10 ng or below at a jetting speed of 8 m/s or above, and
• wherein the flushing operation of the second mode jets a minute liquid particle having a weight of 12 ng or above.

A liquid-jetting apparatus comprising:

• a liquid-jetting head provided with nozzle openings and capable of jetting liquid particles through the nozzle openings;
• and
• a recovering unit to recover from a thickened state in a liquid in the nozzle openings, the recovering unit including a flushing unit that carries out a flushing operation to jet the liquid in the nozzle openings in minute liquid particles,
• wherein a meniscus of the liquid formed in the nozzle opening is retracted greatly immediately before the minute liquid particle is jetted by the flushing unit, and the minute liquid particle is jetted through a central part of the meniscus.

A liquid-jetting apparatus comprising:

• a liquid-jetting head provided with nozzle openings and pressure chambers respectively communicating with the nozzle openings, and capable of varying pressure applied to a liquid contained in the pressure chambers to jet liquid particles through the nozzle openings and of selectively jetting a plurality of kinds of liquid particles respectively having different volumes through each of the nozzle openings;
• and
• a flushing control unit capable of controlling a flushing operation such that the liquid-jetting head jets liquid particles through the nozzle openings to recover from a state of thickened liquid in the nozzle openings;
• wherein the flushing control unit makes the nozzle opening jet at least two kinds of liquid particles among the plurality of kinds of liquid particles respectively having different volumes in one cycle of the flushing operation,
• wherein the two kinds of liquid particles to be jetted in one cycle of the flushing operation include a liquid particle having a smallest volume among those of the plurality of kinds of liquid particles respectively having different volumes, and
• wherein the liquid particle having the smallest volume is jetted first in one cycle of the flushing operation.

A liquid-jetting apparatus comprising:

• a liquid-jetting head provided with nozzle openings and pressure chambers respectively communicating with the nozzle openings, and capable of varying pressure applied to a liquid contained in the pressure chambers to jet liquid particles through the nozzle openings and of selectively jetting a plurality of kinds of liquid particles respectively having different volumes through each of the nozzle openings;
• and
• a flushing control unit capable of controlling a flushing operation such that the liquid-jetting head jets liquid particles through the nozzle openings to recover from a thickened state in a liquid in the nozzle openings;
• wherein the flushing control unit is capable of selecting an optimum flushing mode among a plurality of flushing modes according to a degree of thickening of the liquid in the nozzle opening, and liquid particles among the plurality of kinds of liquid particles respectively having different volumes excluding a liquid particle having a largest volume are jetted for the flushing operation in any one of the plurality of flushing modes.

A method of driving a liquid-jetting apparatus having a liquid-jetting head provided with nozzle openings and pressure chambers respectively communicating with the nozzle openings, and capable of varying pressure applied to a liquid contained in the pressure chambers to jet liquid particles through the nozzle openings and of selectively jetting a plurality of kinds of liquid particles respectively having different volumes through each of the nozzle openings, and a flushing control unit capable of controlling a flushing operation such that the liquid-jetting head jets liquid particles through the nozzle openings to recover from a thickened state in a liquid in the nozzle openings, comprising:

• selecting an optimum flushing mode among a plurality of flushing modes by the flushing control unit according to a degree of thickening of the liquid in the nozzle openings;
• and
• executing the flushing operation so that the liquid particles are jetted through the nozzle openings using a selected flushing mode;
• wherein the liquid particles among the plurality of kinds of liquid particles respectively having different volumes excluding a liquid particle having a largest volume are jetted for the flushing operation in any one of the plurality of flushing modes.

A liquid-jetting apparatus comprising:

• a liquid-jetting head provided with nozzle openings and pressure chambers respectively communicating with the nozzle openings, and capable of varying pressure applied to a liquid contained in the pressure chambers by pressure generating means to jet liquid particles through the nozzle openings, and of selectively jetting a plurality of kinds of liquid particles respectively having different volumes through each of the nozzle openings;
• a driving signal generating unit capable of selectively generating driving signals respectively having different frequencies for driving the pressure generating means;
• a cleaning control unit capable of carrying out a cleaning operation that draws out the liquid through the nozzle openings by suction;
• and
• a flushing control unit capable of carrying out a flushing operation that operates the pressure generating means such that the liquid-jetting head jets liquid particles through the nozzle openings into a non-recording region;
• wherein, after a cleaning operation has been carried out by the cleaning control unit, the flushing control unit carries out a flushing operation by making the driving signal generating unit generate a driving signal of a frequency other than a highest frequency among those of the driving signals that can be generated by the driving signal generating unit to jet liquid particles having a smallest volume among those of the plurality of kinds of liquid particles respectively having different volumes.