Patent ID: 8517510

Claim:
A fluid dispensing apparatus, comprising: a fluid ejector including a nozzle, an ejection chamber in communication with the nozzle, a fluid channel in communication with the ejection chamber, and a fluid reservoir having fluid in communication with the fluid channel; a vacuum pump configured to create negative pressure in an activation mode and to create approximately no pressure in a deactivation mode; a meniscus pressure regulator configured to regulate the negative pressure received from the vacuum pump; a leaking member configured to reduce the negative pressure received from the vacuum pump towards or equal to atmospheric pressure in response to the vacuum pump being placed in the deactivation mode; and a back pressure regulator having a pressure reference port to receive the reduced negative pressure from the leaking member and the regulated negative pressure from the meniscus pressure regulator, the back pressure regulator configured to maintain a non-retraction negative pressure value to position a fluid meniscus in a non-retracted state and a retraction negative pressure value to position the fluid meniscus in a retracted state, wherein the non-retracted state comprises the fluid meniscus disposed in at least one of the nozzle and the ejection chamber downstream of the fluid channel, and the retracted state comprises the fluid meniscus disposed in the fluid channel disposed upstream from the ejection chamber.