Protective circuit for an apparatus
A protective circuit for an apparatus includes an accelerometer having an output and a microcontroller coupled to the output of the accelerometer. The protective circuit also includes a switch for controlling the apparatus coupled to an output of the microcontroller and a load coupled to the switch. A power source is coupled to the load and the switch. In operation the microcontroller is cable of sending a signal to the switch to turn of power to the load when a dangerous condition as detected from the accelerometer data has occurred.
1. A method of controlling an apparatus, comprising the steps of:
a) periodically reading a gravitational value generated by an accelerometer;
b) comparing the gravitational value with a previous gravitational value;
c) incrementing a no motion counter when the gravitational value is substantially the same as the previous gravitational value;
d) resetting the no motion counter to zero when the gravitational value is substantially different from the previous gravitational value;
e) determining if the no motion counter exceeds a threshold;
f) if yes in e), determining whether the gravitational value is within a tolerance difference from a reference gravitational value that is indicative of a known dangerous orientation; and
g) if yes in f), sending a signal to turn off power delivery to a load of the apparatus.
2. The method of claim 1 , wherein the tolerance difference is less than a 10 percent difference.
3. The method of claim 1 , wherein the apparatus is selected from the group consisting of an electric iron, an electric soldering iron, and an electric heater.
4. The method of claim 1 , wherein the apparatus is an electric iron having a toe, a heel, a first side and a second side, and a heating surface and wherein the known dangerous orientation comprises the heating surface of the electric iron being positioned on a support surface.
5. The method of claim 1 , wherein the apparatus is an electric iron having a toe, a heel, a first side and a second side, and a heating surface and wherein the known dangerous orientation comprises either the first side or the second side of the electric iron being positioned on a support surface.
6. A protective circuit for an apparatus, comprising:
an accelerometer having an output;
a microcontroller coupled to the output of the accelerometer;
a switch configured to control delivery of power to the apparatus, said switch coupled to an output of the microcontroller; and
a load of the apparatus coupled to a first terminal of the switch, wherein a second terminal of the switch is configured to be coupled to a power source;
wherein the microcontroller is configured to:
a) receive from the accelerometer a gravitational value;
b) compare the gravitational value with a previous gravitational value;
c) increment a no motion counter when the gravitational value is substantially the same as the previous gravitational value;
d) reset the no motion counter to zero when the gravitational value is substantially different from the previous gravitational value;
e) determine if the no motion counter exceeds a threshold;
f) if yes in e), determine whether the gravitational value is within a tolerance difference from a reference gravitational value that is indicative of a known dangerous orientation; and
g) if yes in f), control the switch to turn off power delivery to the load.
7. The circuit of claim 6 , wherein the accelerometer is a two-axis MEMS accelerometer.
8. The circuit of claim 6 , wherein the accelerometer is a three-axis MEMS accelerometer.
9. The circuit of claim 6 , wherein the tolerance difference is less than a 10 percent difference.
10. The circuit of claim 6 , wherein the apparatus is selected from the group consisting of an electric iron, an electric soldering iron, and an electric heater.
11. The circuit of claim 6 , wherein the apparatus is an electric iron having a toe, a heel, a first side and a second side, and a heating surface and wherein the known dangerous orientation comprises the heating surface of the electric iron being positioned on a support surface.
12. The circuit of claim 6 , wherein the apparatus is an electric iron having a toe, a heel, a first side and a second side, and a heating surface and wherein the known dangerous orientation comprises either the first side or the second side of the electric iron being positioned on a support surface.