Pump dispenser for dispensing accurate small quantities of a fluid substance

Claim 1

A dispenser device of the piston pump type for dispensing accurate small quantities of a fluid substance, in particular an ophthalmological substance, the device comprising: a pump body including a pump chamber having a suction orifice and a discharge orifice; a piston movable between two positions within said pump chamber; and an actuator rod located at one end of said piston; wherein said piston has: a central discharge duct running along the axis of the piston and also along said actuator rod; two axially separated sealing lips; a discharge orifice opening out between said two lips, and in communication with said central discharge duct; an extension head located at the end of the piston opposite from the actuator rod and suitable, on piston displacement, for closing said suction orifice; wherein said pump chamber is formed with shapes in relief disposed in such a manner that a closest one of said sealing lips to said extension head no longer provides sealing when said piston is in positions at which said extension head closes said suction orifice; wherein said discharge orifice is provided with a non-return valve that opens under the effect of compression pressure inside the pump chamber; and wherein said suction orifice is constituted by the central hole through a sealing washer, with said extension head formed on the piston closing the suction orifice by moving into the hole through the washer.