1. Technical Field
The present invention relates to techniques for ejecting liquid, such as ink.
2. Related Art
Hitherto, liquid ejection techniques have been proposed, in which liquid (e.g., ink) contained in a pressure chamber is ejected from a nozzle by changing the pressure in the pressure chamber using a pressure generating element, such as a piezoelectric vibrator or a heating element. In the liquid ejection techniques, a configuration is employed, in which, from the viewpoint of realization of stable ejection by reducing an increase in the viscosity of liquid contained in a pressure chamber, the liquid is appropriately stirred by providing a slight vibration to an extent that the liquid is not ejected. A slight vibration is generated in the pressure chamber by supplying a slight-vibration pulse to a pressure generating element.
JP-A-2002-113858 discloses a slight-vibration pulse QA having a waveform shown in FIG. 10. The slight-vibration pulse QA shown in FIG. 10 is generated as a trapezoidal-shaped pulse including a first changing component Ea1 in which the potential changes in a direction in which the pressure in a pressure chamber is reduced (in a direction in which the pressure chamber is expanded), a holding component Ea2 in which a potential of an end of the first changing component Ea1 is held, and a second changing component Ea3 in which the potential changes in a direction in which the pressure in the pressure chamber is increased (the pressure is reduced and then increased).
Furthermore, JP-A-2005-280199 discloses a slight-vibration pulse QB having a waveform shown in FIG. 11. The slight-vibration pulse QB shown in FIG. 11 is configured so as to include a first changing component Eb1 in which the potential changes in a direction in which a pressure in a pressure chamber is reduced, a second changing component Eb2 in which the potential changes from a potential of an end of the first changing component Eb1 in a direction in which the pressure in the pressure chamber is increased, and a third changing component Eb3 in which the potential changes from a potential of an end of the second changing component Eb2 in a direction in which the pressure in the pressure chamber is reduced (the pressure is reduced, increased, and then reduced).
In a case of sufficiently stirring liquid using a slight vibration on the basis of the techniques disclosed in JP-A-2002-113858 and JP-A-2005-280199, the amplitude of a slight-vibration pulse needs to be increased. However, in a case in which the amplitude of the slight-vibration pulse shown in FIG. 10 or FIG. 11 is increased, there is a high probability that liquid will be accidentally ejected from a nozzle because the pressure in the pressure chamber is excessively increased when the second changing component (Ea3 or Eb2) is supplied to a pressure generating element.