Mist inhaler devices

1. A driver device for a mist inhaler device, the driver device comprising:

a battery;

an AC driver for converting a voltage from the battery into an AC drive signal at a predetermined frequency to drive an ultrasonic transducer;

an active power monitor for monitoring the active power used by the ultrasonic transducer when the ultrasonic transducer is driven by the AC drive signal, wherein the active power monitor provides a monitoring signal which is indicative of an active power used by the ultrasonic transducer;

a processor for controlling the AC driver and for receiving the monitoring signal drive from the active power monitor; and

a memory storing instructions which, when executed by the processor, cause the processor to:

A) control the AC driver to output an AC drive signal to the ultrasonic transducer at a predetermined sweep frequency;

B) calculate the active power being used by the ultrasonic transducer based on the monitoring signal;

C) control the AC driver to modulate the AC drive signal to maximise the active power being used by the ultrasonic transducer;

D) store a record in the memory of the maximum active power used by the ultrasonic transducer and the sweep frequency of the AC drive signal;

E) repeat steps A-D for a predetermined number of iterations with the sweep frequency incrementing with each iteration such that, after the predetermined number of iterations has occurred, the sweep frequency has been incremented from a start sweep frequency to an end sweep frequency;

F) identify from the records stored in the memory an optimum frequency for the AC drive signal which is the sweep frequency of the AC drive signal at which a maximum active power is used by the ultrasonic transducer; and

G) control the AC driver to output an AC drive signal to the ultrasonic transducer at the optimum frequency to drive the ultrasonic transducer to atomise a liquid; and

a current sensor for sensing a drive current of the AC drive signal driving the ultrasonic transducer, wherein the active power monitor provides a monitoring signal which is indicative of the sensed drive current.

2. The driver device of claim 1 , wherein the memory stores instructions which, when executed by the processor, cause the processor to:

repeat steps A-D with the sweep frequency being incremented from a start sweep frequency of 2900 kHz to an end sweep frequency of 2960 kHz.

3. The driver device of claim 1 , wherein the memory stores instructions which, when executed by the processor, cause the processor to:

repeat steps A-D with the sweep frequency being incremented from a start sweep frequency of 2900 kHz to an end sweep frequency of 3100 kHz.

4. The driver device of claim 1 , wherein the memory stores instructions which, when executed by the processor, cause the processor to:

in step G, control the AC driver to output an AC drive signal to the ultrasonic transducer at frequency which is shifted by between 1-10% of the optimum frequency.

5. The driver device of claim 1 , wherein the driver device further comprises:

a wireless communication circuit which is in communication with the processor, the wireless communication circuit including a transceiver to transmit and receive data over a wireless network between the driver device and a remote computing device including a further transceiver.

6. The driver device of claim 1 , wherein the AC driver modulates the AC drive signal by pulse width modulation to maximise the active power being used by the ultrasonic transducer.

7. The driver device of claim 1 , wherein the driver device is releasably attached to a mist generator device such that the driver device is separable from the mist generator device.

8. The driver device of claim 1 , wherein the current sensor comprises:

an Analog-to-Digital Converter which converts the sensed drive current into a digital signal for processing by the processor.

9. The driver device of claim 4 , wherein the predetermined shift amount is between 1-10% of the optimum frequency.

10. The driver device of claim 1 , wherein the battery is a 3.7V DC Li—Po battery.

11. The driver device of claim 1 , wherein the driver device further comprises:

a driver housing which is at least partly made of metal, wherein the driver device housing houses the battery, the processor, the memory, the active power monitor and the AC driver, and wherein the driver device housing comprises a recess for receiving and retaining part of a mist generator device.