Security event detection with smart windows
Optically controllable windows and an associated window control system provide a building security platform. A window controller or other processing device can monitor for window breakage, cameras associated with windows can monitor for intruders, and transparent displays can provide alerts regarding detected activity within a building. A window control system can detect deviations from expected I/V characteristics of an optically controllable window during normal operation of the window (tint transitions, steady state conditions, etc.) and/or during application of a security-related perturbing event, and provide alerts upon their occurrence.
1. A method of detecting breakage in an optically switchable window, the method comprising:
(a) applying a current or voltage to the optically switchable window; and
(b) measuring an electrical response to the current or voltage applied in (a) to determine whether the measured electrical response is consistent with breakage of the optically switchable window;
wherein (a) is performed irrespective of a current tint state or a current transition between tint states of the optically switchable window and the optically switchable window is not visibly perturbed as a result of (a).
2. The method of claim 1 , further comprising:
(c) in response to detecting the response in (b), performing a security action.
3. The method of claim 1 , wherein measuring the electrical response is performed while the optically switchable window is undergoing a transition from a first tint state to a second tint state.
4. The method of claim 1 , wherein measuring the electrical response includes measuring an open circuit voltage of the optically switchable window.
5. The method of claim 4 , wherein measuring the open circuit voltage of the optically switchable window is performed while the optically switchable window is undergoing a transition from a first tint state to a second tint state.
6. The method of claim 1 , further comprising comparing the electrical response measured in (b) with an expected current or voltage for driving the transition between tint states and/or for maintaining an end optical state of the optically switchable window.
7. The method of claim 6 , wherein the expected current or voltage is a previously measured current or voltage for driving the transition between optical states and/or for maintaining the end optical state of the optically switchable window.
8. The method of claim 6 , wherein measuring the electrical response of the optically switchable window is performed while the optically switchable window is in the end optical state.
9. The method of claim 1 , wherein measuring the electrical response of the optically switchable window includes measuring a leakage current of the optically switchable window and comparing the measured leakage current against an expected leakage current of the optically switchable window.
10. A system comprising:
one or more interfaces for receiving sensed values for an optically switchable device of an optically switchable window; and
one or more processors and memory configured to perform a method of detecting breakage in an optically switchable window, the method comprising:
(a) applying a current or voltage to the optically switchable window; and
(b) measuring an electrical response to the current or voltage applied in (a) to determine whether the measured electrical response is consistent with breakage of the optically switchable window;
wherein (a) is performed irrespective of a current tint state or a current transition between tint states of the optically switchable window and the optically switchable window is not visibly perturbed as a result of (a).
11. The system of claim 10 , wherein the method further comprises:
(c) in response to detecting the response in (b), performing a security action.
12. The system of claim 10 , wherein measuring the electrical response is performed while the optically switchable window is undergoing a transition from a first tint state to a second tint state.
13. The system of claim 10 , wherein measuring the electrical response includes measuring an open circuit voltage of the optically switchable window.
14. The system of claim 13 , wherein measuring the open circuit voltage of the optically switchable window is performed while the optically switchable window is undergoing a transition from a first tint state to a second tint state.
15. The system of claim 10 , wherein the method further comprises comparing the electrical response measured in (b) with an expected current or voltage for driving the transition between tint states and/or for maintaining an end optical state of the optically switchable window.
16. The system of claim 15 wherein the expected current or voltage is a previously measured current or voltage for driving the transition between optical states and/or for maintaining the end optical state of the optically switchable window.
17. The system of claim 15 , wherein measuring the electrical response of the optically switchable window is performed while the optically switchable window is in the end optical state.
18. The system of claim 10 , wherein measuring the electrical response of the optically switchable window includes measuring a leakage current of the optically switchable device and comparing the measured leakage current against an expected leakage current of the optically switchable window.