LIQUID DROPLET EJECTING APPARATUS AND LIQUID DROPLET EJECTING METHOD

摘要

A liquid droplet ejecting apparatus having: a liquid droplet ejecting head; and a drive pulse generating unit, wherein the head includes: a nozzle; a pressure chamber which communicates with the nozzle; and a pressure applying section which changes a pressure in the pressure chamber, wherein the generated drive pulse is applied to the pressure applying section so as to change the pressure in the pressure chamber to cause 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 the pulse width PW of the expanding pulse is set so as to satisfy the following conditional equation, $\begin{array}{cc}\mathrm{PW}=\frac{\mathrm{pi}-\left({\tan }^{-1}\frac{1}{2\mathrm{pi}f\mathrm{tau}}\right)}{2\mathrm{pi}f}& \left(1\right)\end{array}$ where f represents an acoustic resonance frequency of a pressure wave in the pressure chamber and tau represents a damping time constant of the pressure wave.