Liquid ejecting apparatus and liquid ejecting head unit

A liquid ejecting head unit mounted on a liquid ejecting apparatus including

• an ejecting section configured to eject liquid to a print medium,
• a movement mechanism configured to change the relative positional relationship between the print medium and the ejecting section, and
• an encoder configured to include a scale, a light emitting element emitting light to the scale, and a light receiving element which receives light reflected by the scale or light transmitted through the scale in the emitted light and configured to output information changed in accordance with a change in the positional relationship, the liquid ejecting head unit comprising:
• the ejecting section;
• a signal generation section configured to generate a pulse signal including a pulse prescribing a timing when the ejecting section ejects liquid based on the information;
• a measurement section configured to measure a time length between pulses included in the pulse signal;
• and
• an ejection restriction section configured to restrict ejection of liquid from the ejecting section when the time length is larger than a threshold value.