Patent ID: 7950760

Claim:
A liquid droplet ejecting apparatus comprising: a liquid droplet ejecting head; and a drive pulse generating unit adapted to generate a drive pulse, wherein the liquid ejecting head includes: a nozzle which ejects liquid droplets; a pressure chamber which communicates with the nozzle; and a pressure applying section which changes a pressure in the pressure chamber by expanding or reducing a volume of the pressure chamber, wherein the drive pulse generated by the drive pulse generating unit is applied to the pressure applying section so as to change the pressure in the pressure chamber and the change of pressure in the pressure chamber causes the liquid in the pressure chamber to be ejected from the nozzle, and wherein the drive pulse comprises a rectangular expansion pulse which causes expansion and then contraction of the volume of the pressure chamber and in which a pulse width PW of the expanding pulse is set so as to satisfy the following conditional equation, PW = π - ( tan - 1 ⁢ 1 2 ⁢ π ⁢ ⁢ f ⁢ ⁢ τ ) 2 ⁢ π ⁢ ⁢ f ( 1 ) where f represents an acoustic resonance frequency of a pressure wave in the pressure chamber and τ represents a damping time constant of the pressure wave.