公开(公告)号：US20180290457A1

公开(公告)日：2018-10-11

申请号：US15570660

申请日：2015-07-24

Applicant: HEWLETT-PACKARD DEVELOPMENT COMPANY, L.P.

Inventor： Ning Ge ,  Leong Yap Chia ,  Wei Mun Wong ,  Ser Chia Koh

IPC: B41J2/175 ,  B41J2/14

Abstract: In an example implementation, a method of operating a fluid sensing device includes enabling a fluid level sensing circuit on a printhead to determine a fluid level by sharing an applied charge between a capacitive sensor and a reference capacitor to determine a capacitance value of the capacitive sensor. The method includes enabling a fluid property sensing circuit on the printhead to determine a fluid property by measuring a transistor voltage that indicates a concentration of ions gathered on the capacitive sensor.