Electronic vapor provision system having a sleep mode

1 . An electronic vapor provision system including:

a vaporizer for vaporizing liquid for inhalation by a user of the electronic vapor provision system;

a power supply comprising a cell or a battery for supplying power to the vaporizer; and

a control unit for controlling the supply of power from the power supply to the vaporizer, the control unit having a sleep mode in which no power is supplied to the vaporizer and a user mode in which power is available for supply to the vaporizer, whereby the control unit reverts from the user mode to the sleep mode in response to one of a plurality of triggers, the plurality of triggers including a trigger representing a predetermined amount of time of inactivity in the user mode and another trigger representing that the vaporizer has been disengaged from the power supply.

2 . The electronic vapor provision system according to claim 1 , wherein the predetermined amount of time of inactivity in the user mode is greater than 4 minutes.

3 . The electronic vapor provision system according to claim 1 , wherein the control unit is transferred back to the user mode by disengaging and re-engaging the vaporizer with the power supply.

4 . The electronic vapor provision system according to claim 1 , wherein the control unit is transferred back to the user mode by re-engaging the vaporizer with the power supply.

5 . The electronic vapor provision system according to claim 1 , wherein the electronic vapor provision system further includes a capacitor configured to be electrically connected to the vaporizer, and wherein the control unit is configured to charge the capacitor after a predetermined time has elapsed, and to monitor discharge of the capacitor to determine whether the vaporizer is electrically connected to the capacitor.

6 . The electronic vapor provision system according to claim 5 , wherein the predetermined time is two seconds.

7 . An electronic vapor provision system according to claim 5 , wherein the control unit is configured to revert back to the user mode if the capacitor discharges in a period of time shorter than the predetermined time.

8 . The electronic vapor provision system according to claim 1 , wherein the electronic vapor provision systems includes a pressure drop sensor or an air flow sensor for monitoring inhalation by a user through the electronic vapor provision system; wherein the control unit is for detecting a start and an end of an inhalation based on readings from the pressure drop sensor or the air flow sensor; and wherein the control unit is configured to:

monitor a cumulative period of inhalation (Ti) over a predetermined window (Tw); and

transfer the electronic vapor provision system to the sleep mode if the cumulative period of inhalation (Ti) exceeds a predetermined threshold (Th).

9 . The electronic vapor provision system according to claim 8 , wherein the control unit is further configured to:

monitor a period of inhalation;

if the period of inhalation exceeds a first threshold:

render the electronic vapor provision system inactive for a predetermined period, and

render the electronic vapor provision system active after the predetermined period has expired; and

monitor a period of the next inhalation such that if the period of the next inhalation exceeds a second threshold:

transfer the electronic vapor provision system to the sleep mode.

10 . The electronic vapor provision system according to claim 1 , further including:

a pressure drop sensor or an air flow sensor for monitoring inhalation by a user through the electronic vapor provision system; and

wherein the control unit is for detecting a start and an end of inhalation based on readings from the pressure drop sensor or the air flow sensor, wherein the control unit is configured to:

monitor the period of inhalation;

if the period of inhalation exceeds a first threshold:

render the electronic vapor provision system inactive for a predetermined period, and

render the electronic vapor provision system active after the predetermined period has expired;

monitor a period of the next inhalation such that if the period of the next inhalation exceeds a second threshold:

transfer the electronic vapor provision system to the sleep mode.

11 . The electronic vapor provision system according to claim 1 , further comprising:

a pressure drop sensor or an air flow sensor for monitoring inhalation by a user through the electronic vapor provision system;

wherein the control unit is for detecting a start and an end of inhalation based on readings from the pressure drop sensor or the air flow sensor;

wherein the control unit is configured to:

detect the start of inhalation when the pressure drop sensor or the air flow sensor reading departs by more than a first threshold from a previous reading; and

detect the end of inhalation when the pressure drop sensor or the air flow sensor reading departs by less than a second threshold from the previous reading, wherein the first threshold is greater than the second threshold.

12 . An electronic vapor provision system including:

a vaporizer for vaporizing liquid for inhalation by a user of the electronic vapor provision system;

a power supply comprising a cell or a battery for supplying power to the vaporizer; and

a control unit for controlling the supply of power from the power supply to the vaporizer, the control unit having a sleep mode in which no power is supplied to the vaporizer and a user mode in which power is available for supply to the vaporizer, wherein in the user mode, the control unit is configured to cut power to the vaporizer after a predetermined time from the start of vaporization, whereby the control unit reverts from the user mode to the sleep mode in response to one of a plurality of triggers, the plurality of triggers including a trigger representing a predetermined amount of time of inactivity in the user mode and another trigger representing that the vaporizer has been disengaged from the power supply.