Liquid ejection apparatus

A liquid ejection apparatus, comprising:

• a nozzle through which liquid is ejected;
• a pressure chamber which accommodates the liquid to be ejected from the nozzle;
• a supply side flow path which fills the liquid from a supply system into the pressure chamber;
• an actuator which is provided on at least one wall of the pressure chamber and changes a volume of the pressure chamber;
• and
• a drive signal generating device which generates a drive signal including at least a first drive signal having a time period T1 which drives the actuator so as to expand the pressure chamber, and a second drive signal having a time period T2 which drives the actuator so as to contract the pressure chamber, wherein:
• a relationship between the time period T2 of the second drive signal and a Helmholtz period Tc of the pressure chamber satisfies T2≦Tc/2;
• and
• when the actuator is operated by means of the drive signal to generate, in the nozzle, a pressure having a prescribed cycle in which a negative pressure acting in a direction which causes the pressure chamber to expand, and a positive pressure acting in a direction which causes the pressure chamber to contract arise alternately, a relationship between an absolute value of a first negative pressure Pn1 generated initially from a static meniscus state of the liquid in the nozzle and an absolute value of a second negative pressure Pn2 generated one cycle after the first negative pressure, satisfies |Pn1|≦|Pn2|,
• wherein the following relationship is satisfied
• (
• 0.4811
• π
• )
• 2
• ⨯
• ρ
• ln
• ⨯
• A
• ⁢
• ⁢
• s
• +
• l
• ⁢
• ⁢
• s
• ⨯
• A
• ⁢
• ⁢
• n
• {
• 1
• +
• (
• 0.4811
• π
• )
• 2
• }
• ⨯
• (
• V
• ρ
• ⨯
• c
• 2
• +
• X
• P
• )
• ≥
• 2
• ⨯
• π
• ⨯
• v
• ln
• ⨯
• A
• ⁢
• ⁢
• s
• 2
• +
• l
• ⁢
• ⁢
• s
• ⨯
• A
• ⁢
• ⁢
• n
• 2
• ≥
• (
• 0.2813
• π
• )
• 2
• ⨯
• ρ
• ln
• ⨯
• A
• ⁢
• ⁢
• s
• +
• l
• ⁢
• ⁢
• s
• ⨯
• A
• ⁢
• ⁢
• n
• ⁢
• {
• 1
• +
• (
• 0.2813
• π
• )
• 2
• }
• ⨯
• (
• V
• ρ
• ⨯
• c
• 2
• +
• X
• P
• )
• where ln is a length of the nozzle;
• An is a surface area of the nozzle;
• ls is a length of the supply side flow path;
• As is a surface area of the supply side flow path;
• ρ is a density of the liquid;
• v is a viscosity of the liquid;
• c is a speed of sound in the liquid;
• V is a removed volume of the liquid accommodated in the pressure chamber when a pressure P is generated by the actuator;
• and X is a removed volume of total of a volume of the liquid ejected from the nozzle, a volume of the liquid returning to the supply side flow path, and a volume of the liquid compressed due to application of the pressure P.