Printhead Scan Waiting Control to Prevent Nozzle Drying

The patent applies dynamics by making the waiting time variable rather than fixed. The control unit dynamically adjusts the waiting time at the back position based on whether preliminary ejection has been performed. When preliminary ejection is performed, a longer waiting time is allowed; when it is not performed, a shorter waiting time is applied. This dynamic adjustment resolves the contradiction between providing sufficient liquid fixing time and preventing nozzle surface drying.

The patent applies parameter changes by modifying the waiting time parameter based on the ejection history. The control unit changes the waiting time parameter at the back position from a fixed value to a conditional value that depends on whether preliminary ejection was performed. This parameter adjustment allows the system to achieve adequate liquid fixing time while avoiding nozzle surface drying by reducing waiting time when preliminary ejection has not been performed.

The patent applies preliminary action by performing preliminary ejection at the home position before the forward scan. This preliminary ejection ensures that the nozzle surface is properly prepared and allows the system to allocate sufficient liquid fixing time at the home position where maintenance mechanisms are available. By performing the ejection action in advance at the appropriate position, the system avoids delays in the backward scan timing while still achieving adequate liquid fixing.