Dosing device and writing implement with a dosing device

摘要

A dosing device for demand-dosing a liquid includes a primary container (10), a point of release (22) for releasing the liquid, a main liquid channel (16) between the primary container (10) and the point of release (22) and a vented secondary container (26), wherein the secondary container (26) is coupled to the main liquid channel 16 at a branch point (20), wherein the secondary container (26) and the main liquid channel (16) are designed such that the main liquid channel (16) preferably fills with the liquid before the secondary container (26). The dosing device further includes a liquid valve (18) between the primary container (10) and the branch point (20), a sensor (30) for measuring the filling level in the secondary container (26) and finally means (32) for opening the valve (18) responsive to a predetermined filling level in the secondary container (26). By measuring the flow not directly in the main stream but via a filling level of a secondary container in an auxiliary stream, the secondary container can be designed independently of ambient temperature and ambient pressure so that cases of failure due to changing ambient conditions do no longer occur. A preferred application of the dosing system is the use of it in an electronic writing apparatus.