Liquid Jetting Apparatus

A liquid jetting apparatus, comprising:

• a head configured to jet liquid supplied from a liquid tank;
• a memory configured to store initial viscosity data and pieces of reference data, the initial viscosity data being related to initial viscosity which is viscosity of the liquid in the liquid tank at an initial timing point at which the liquid in the liquid tank is suppliable to the head, each of the pieces of reference data being reference data related to estimated change in the viscosity of the liquid in the liquid tank on an assumption that a supply amount of the liquid supplied from the liquid tank per unit time is a fixed amount, the pieces of reference data being different in the fixed amount;
• and
• a controller configured to estimate the viscosity of the liquid in the liquid tank every time a predefined time passes and to store, in the memory, the viscosity estimated as viscosity of the liquid in the liquid tank at the time of the estimation,
• wherein, in the case of estimating the viscosity of the liquid in the liquid tank, the controller is configured to:
• acquire a cumulative supply amount including at least a total supply amount of the liquid supplied from the liquid tank after the initial timing point and before a most-recent estimation timing point of the viscosity of the liquid in the liquid tank, and a supply amount of the liquid supplied from the liquid tank per unit time within the predefined time,
• estimate a viscosity change amount being a change amount of the viscosity of the liquid in the liquid tank within the predefined time based on the cumulative supply amount acquired, the supply amount per unit time acquired, and the pieces of reference data stored in the memory, and
• estimate the viscosity of the liquid in the liquid tank based on the viscosity change amount estimated, and the initial viscosity or a latest viscosity of the liquid in the liquid tank being stored in the memory before a current estimation timing point of the viscosity of the liquid in the liquid tank.