US 11,807,019 B2
Printing fluid circulation
Ronald Albert Askeland, San Diego, CA (US); Blair A. Butler, San Diego, CA (US); Ronald J. Ender, Corvallis, OR (US); Craig L. Malik, Corvallis, OR (US); Daniel D. Dowell, Corvallis, OR (US); Seth Stephen Haddix, Corvallis, OR (US); Si-Lam J. Choy, Corvallis, OR (US); and Alexander Govyadinov, Corvallis, OR (US)
Assigned to Hewlett-Packard Development Company, L.P., Spring, TX (US)
Appl. No. 17/312,366
Filed by Hewlett-Packard Development Company, L.P., Spring, TX (US)
PCT Filed Jul. 31, 2019, PCT No. PCT/US2019/044492
§ 371(c)(1), (2) Date Jun. 9, 2021,
PCT Pub. No. WO2021/021193, PCT Pub. Date Feb. 4, 2021.
Prior Publication US 2022/0161568 A1, May 26, 2022
Int. Cl. B41J 2/175 (2006.01)
CPC B41J 2/17596 (2013.01) 16 Claims
OG exemplary drawing
 
1. An inkjet pen comprising:
a plurality of fluid ports,
a first fluid port to deliver printing fluid to a fluid ejection device and a second fluid port to direct printing fluid out of the pen;
a pressure regulator in fluid communication with the first fluid port of the plurality of fluid ports; and
a valve in fluid communication with the second fluid port of the plurality of fluid ports;
in response to negative pressure, the valve to open to enable fluids within the pen to exit via the second fluid port.