Protective circuit for an apparatus

• US 9,899,170 B2
• Filed: 02/16/2016
• Issued: 02/20/2018
• Est. Priority Date: 12/09/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Hopkins, Thomas L.
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): PARRIES, DRU M
• Application Number:
  US15/044,762
• Publication Number:
  US 20160163485A1
• Time in Patent Office: 735 Days
• Field of Search: 307326
• CPC Class Codes: D06F 75/26 Temperature control or indicating arrangements
• CPC Class Codes: G05B 9/02 electric
• CPC Class Codes: H01H 2231/012 Household appliance
• CPC Class Codes: H01H 35/02 Switches operated by change of position, inclination or orientation of the switch itself in relation to gravitational field tilting mercury container H01H29/20; change of position due to change of liquid level H01H35/18
• CPC Class Codes: H01H 35/14 Switches operated by change of acceleration, e.g. by shock or vibration, inertia switch wherein the liquid constitutes a contact of the switch H01H29/002

Abstract

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.

Claims

1. A method of controlling an apparatus, comprising the steps of:

a) periodically reading values from an accelerometer, wherein the values include a first gravitational value in a first direction and a second gravitational value in a second direction being substantially perpendicular to the first direction;

b) comparing the first and second gravitational values with previous first and second gravitational values;

c) incrementing a no motion counter when the first and second gravitational values are substantially the same as the previous first and second gravitational values;

d) resetting the no motion counter to zero when the first and second gravitational values are substantially different from the previous first and second gravitational values;

e) determining if the no motion counter exceeds a threshold;

f) if yes in e), determining whether the first and second gravitational values are within a tolerance difference from reference first and second gravitational values 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;

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 first gravitational value in a first direction and a second gravitational value in a second direction being substantially perpendicular to the first direction;

b) compare the first and second gravitational values with previous first and second gravitational values;

c) increment a no motion counter when the first and second gravitational values are substantially the same as the previous first and second gravitational values;

d) reset the no motion counter to zero when the first and second gravitational values are substantially different from the previous first and second gravitational values;

e) determine if the no motion counter exceeds a threshold;

f) if yes in e), determine whether the first and second gravitational values are within a tolerance difference from reference first and second gravitational values 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.