Triggering circuit for an aerosol drug-dispensing device
AssigneeThe Technology Partnership PLC
InventorMartin Scott Goodchild
Life of this patent
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Abstract
An electronic gas flow triggering circuit for use in an aerosol drug dispensing device has a voltage source and a self-nulling circuit to which voltage is supplied from the voltage source. A hot wire anemometer filament forms a component of the bridge circuit which is adapted to maintain a constant resistance of the anemometer filament, the bridge drive voltage being dependent upon the gas flow across the anemometer filament. A comparator compares the bridge output voltage with a reference voltage and provides a triggering signal to operate the device if the bridge drive voltage is greater than the reference voltage.
Claims4
An electronic gas flow triggering circuit for use in an aerosol drug dispensing device, the circuit including:
- a voltage source;
- a self-nulling bridge circuit to which voltage is supplied from the voltage source;
- a hot wire anemometer filament forming a component of the bridge circuit which is adapted to maintain a constant resistance of the anemometer filament, the bridge drive voltage being dependent upon the gas flow across the anemometer filament;
- and
- a comparator for comparing the bridge drive voltage with a reference voltage such that a trigger signal is provided if a certain rate of change of gas flow is exceeded.
Dependencies are inferred from the claim text.