| 摘要 |
<p>A liquid dispensing apparatus having a container with an anti-drip valve cartridge mounted thereon. The problem associated with the conventional apparatus to prevent drip between dispensing intervals is the difficulty to accurately meter the dispensing of minute quantities of liquid. The present invention provides a pressure activated poppet valve within the anti-drip valve cartridge that seals the outlet thereof when the container is depressurized and opens the outlet when the container is pressurized. Also, a needle element is mounted at the outlet opening which contains a volume of liquid which exerts a pressure that is less than the incoming atmospheric pressure acting against the liquid at the outlet end of the needle element after a dispensing cycle so that liquid will not drip therefrom. Pressurized air (130) is provided for pressurizing the container (80) for the duration of a time interval and for depressurizing the container (80) to atmospheric pressure, simultaneously, with the end of the time interval. The valve cartridge (30) has an outlet portion (62) which sealably connects an outlet opening (35) thereof in registry with the bore (23) of the needle element (20). A pressure activated poppet valve (70) is provided in the valve cartridge to seal the outlet opening (35) upon the depressurization of the container (80). After depressurization, a volume of liquid (81) is left in the needle element (20) which exerts a pressure at the end (20a) of the needle element (20) that is less than the incoming atmospheric pressure. As a result, liquid will not drip from the end (20a) of the needle element (20) after the depressurization of the container (80) and thus the dispensing of the liquid.</p> |
