Patent ID: 6886607

Claim:
A function liquid filling apparatus which fills a passage inside a function liquid droplet ejection head connected to a function liquid tank with a function liquid in said function liquid tank by coupling a head cap connected to a waste liquid passage to said function liquid droplet ejection head, thereby feeding the function liquid toward said head cap through said function liquid droplet ejection head, said apparatus comprising: feed means for feeding the function liquid in the function liquid tank toward said head cap through said function liquid droplet ejection head; detection means for detecting a state in that the fed function liquid reaches said head cap; and control means for stopping drive of said feed means based on a result of detection by said detection means, wherein said detection means comprises a crystal oscillator disposed in at least one of inside said head cap and inside said waste liquid passage, and a detector for detecting presence or absence of the function liquid based on a change in a resonance frequency of said crystal oscillator.