Vaporization device control systems and methods

Patent metadata

Field	Value
Publication number	US-10912333-B2
Application number	US-201716080296-A
Country	US
Kind code	B2
Filing date	Feb 27, 2017
Priority date	Feb 25, 2016
Publication date	Feb 9, 2021
Grant date	Feb 9, 2021

Abstract

Vaporization devices and methods of operating them. In particular, described herein are methods for controlling the power applied to a resistive heater of a vaporization device by measuring the resistance of the resistive heater at discrete intervals. Changes in the resistance during heating may be used to control the power applied to heat the resistive heater during operation. Also described herein are vaporization devices that are configured to measure the resistance of the resistive heater during heating and to control the application of power to the resistive heater based on the resistance values.

First claim

What is claimed is:

1. A device comprising:
a reservoir configured to hold a vaporizable material;
a resistive heater configured to heat the vaporizable material;
a resistance measurement circuit configured to measure a current resistance of the resistive heater;
a power source; and
a controller configured to perform operations comprising:
determining whether a rate of change in resistance, of the resistive heater with time, is below a stability threshold during a period of time when power is not applied to the resistive heater;
determining a baseline resistance of the resistive heater based on the rate of change in resistance of the resistive heater being below the stability threshold;
determining, based on the determined baseline resistance of the resistive heater and a target change in resistance of the resistive heater, a target resistance of the resistive heater correlated to a target temperature of the resistive heater;
applying power from the power source to heat the resistive heater; and
adjusting the power applied to the resistive heater based on a difference between the current resistance of the resistive heater and the target resistance of the resistive heater.

2. The device of claim 1 , further comprising:
a sensor having a sensor output connected to the controller,
wherein the controller is configured to perform operations comprising:
determining, based on the sensor output, when the resistive heater applies the power from the power source to heat the resistive heater.

3. The device of claim 2 , wherein the sensor comprises a pressure sensor, wherein the controller is configured to perform operations comprising:
applying the power from the power source to heat the resistive heater when the pressure sensor detects a change in pressure.

4. The device of claim 1 , further comprising:
a target resistance circuit configured to determine the target resistance.

5. The device of claim 4 , further comprising:
a comparison circuit configured to compare the current resistance of the resistive heater to the target resistance, wherein the comparison circuit comprises a Wheatstone bridge, an amplified Wheatstone bridge, or an RC charge time circuit.

6. The device of claim 1 , further comprising:
a temperature input configured to provide an actual temperature of the resistive heater to the controller.

7. The device of claim 1 , wherein the determined baseline resistance comprises an ambient resistance of the resistive heater at an ambient temperature.

8. The device of claim 1 , wherein the controller is further configured to perform operations comprising:
calculating a current temperature from the current resistance of the resistive heater and a temperature coefficient of resistivity for the resistive heater.

9. The device of claim 8 , wherein the controller is further configured to perform operations comprising:
providing the current temperature for display on an output in communication with the controller.

10. The device of claim 1 , further comprising a wick in communication with the reservoir and adjacent to the resistive heater.

11. The device of claim 1 , applying the power to the resistive heater to heat the resistive heater comprises applying the power to the resistive heater at an applied power duty cycle.

12. The device of claim 11 , wherein the applied power duty cycle is based on the difference between the current resistance of the resistive heater and the target resistance of the resistive heater.

13. The device of claim 11 , wherein the applied power duty cycle is limited to a maximum duty cycle.

14. The device of claim 13 , wherein the controller is further configured to perform operations comprising:
determining a maximum average power in the resistive heater based on a battery voltage measurement and the current resistance of the resistive heater, wherein the maximum duty cycle corresponds to the maximum average power.

15. The device of claim 1 , wherein the determined baseline resistance of the resistive heater is determined when the resistive heater has been unpowered for more than 10 seconds and the rate of change in resistance is below the stability threshold.

16. The device of claim 1 , wherein the stability threshold is a less than 1% change in resistance per millisecond.

17. The device of claim 1 , wherein the stability threshold is a less than 5% change in resistance per millisecond.

18. The device of claim 1 , further comprising:
a device body comprising the resistance measurement circuit, the power source, and the controller; and
a separable cartridge comprising the reservoir and the resistive heater.

19. The device of claim 1 , further comprising the vaporizable material, wherein the vaporizable material comprises a nicotine formulation.

20. The device of claim 1 , wherein determining the target resistance of the resistive heater correlated to the temperature of the resistive heater comprises:
determining a change in resistance corresponding to a percentage of the determined baseline resistance, and
adding the change in resistance to the determined baseline resistance.

21. The device of claim 1 , wherein the resistive heater is configured to thermally contact the vaporizable material held in the reservoir.

22. A method of controlling a device comprising a reservoir configured to hold a vaporizable material and a resistive heater configured to heat the vaporizable material, the method comprising:
measuring a current resistance of the resistive heater;
determining a baseline resistance of the resistive heater, the determining the baseline resistance comprising determining that a rate of change in a measured resistance, of the resistive heater with time, is below a stability threshold during a period of time when power is not applied to the resistive heater;
calculating a target resistance of the resistive heater correlated to a target temperature of the resistive heater, the calculating of the target resistance based on the determined baseline resistance of the resistive heater and a target change in resistance of the resistive heater;
applying power from a power source to heat the resistive heater; and
adjusting the power applied to the resistive heater, based on a difference between the current resistance of the resistive heater and the target resistance of the resistive heater.

23. The method of claim 22 , further comprising:
storing the determined baseline resistance of the resistive heater in a memory.

Assignees

• Juul Labs Inc

Inventors

• Atkins Ariel
• Christensen Steven
• Hatton Nicholas J

Classifications

• A24F40/57 Primary

  Temperature control · CPC title

• A24F40/10

  Devices using liquid inhalable precursors · CPC title

• A24F40/51

  Arrangement of sensors · CPC title

• H05B2203/022

  Heaters specially adapted for heating gaseous material · CPC title

• A61M2205/8206

  battery-operated · CPC title