Patent ID: 7452059

Claim:
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 T 1 which drives the actuator so as to expand the pressure chamber, and a second drive signal having a time period T 2 which drives the actuator so as to contract the pressure chamber, wherein: a relationship between the time period T 2 of the second drive signal and a Helmholtz period Tc of the pressure chamber satisfies T 2 ≦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 Pn 1 generated initially from a static meniscus state of the liquid in the nozzle and an absolute value of a second negative pressure Pn 2 generated one cycle after the first negative pressure, satisfies |Pn 1 |≦|Pn 2 |, 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.