GREASE BUILDUP SENSOR

1 . A device for determining an aggregate amount of grease along a conductor at a predetermined height over a conducting surface comprising:

a predetermined length of a conductor on which a source signal is transmitted;

a source placed at one end of the conductor;

a receiver placed at the opposite end of the conductor; and

a timer circuit to measure the time between when the source sends the signal and when the signal arrives at the receiver.

2 . A method of measuring an aggregate amount of grease along a conductor at a predetermined height over a conducting surface comprising:

initiating setting a first reference delay value and a second reference delay value to a time less than the delay along the grease sensor conductor path;

setting a third reference delay value to zero if the expected grease sensor conductor delay is less than the total first reference delay value and second reference delay value time;

setting the third reference delay to 1 if the grease sensor conductor delay is expected to be greater than a first clock period but less than twice the first clock period, where the third reference delay is incremented higher for each additional clock period that the grease sensor conductor delay is expected to be the number of clock periods longer in time; and

initiating a launch of a signal along the grease sensor conductor path and the first reference delay value and second reference delay value paths,

wherein if the reference signal arrives before a signal clock input then the output of the capture reference will be high, and the first reference delay value and second reference delay values are increased for another iteration.

3 . A device for detecting an amount of grease deposit in a cooking exhaust vent, comprising:

a conductor having a first end and a second end, where each end is configured for positioning outside a cooking exhaust vent;

a midsection between the first and second ends, the midsection configured for positioning within the cooking exhaust vent along a conducting surface of a cooking exhaust vent; and

a module configured for positioning outside the cooking exhaust vent, the module having a signal source connected to the first end of the conductor for transmitting a signal at the first end of the conductor, a receiver connected to the second end of the conductor for receiving the signal at the second end of the conductor, and a timer circuit for measuring a time between transmission of the signal at the first end and reception of the signal at the second end, wherein the time indicates the amount of grease deposit in the cooking exhaust vent.

4 . The device of claim 3 , wherein the electronics module is configured to determine the amount of grease deposit based on a comparison between the measured time and an expected signal time delay when the cooking exhaust vent has no grease.

5 . The device of claim 3 , wherein the midsection of the conductor is configured for positioning along the conducting surface of the cooking exhaust vent without contacting the conducting surface.

6 . The device of claim 3 , wherein the midsection of the conductor is configured for positioning along the conducting surface of the cooking exhaust vent substantially parallel to the conducting surface.

7 . The device of claim 3 , further comprising one or more insulating tabs for positioning between the midsection of the conductor and the conducting surface to prevent contact between the conductor and the conducting surface.

8 . The device of claim 3 , wherein the midsection of the conductor forms a loop such that the first and second ends of the conductor are adjacent to each other.

9 . The device of claim 3 , further comprising a second conductor extending parallel to the conductor to form a differential pair with the conductor.