System and method for calibrating an electro-permanent magnet key switch assembly

1. A plurality of electro-permanent magnet (EPM) key assemblies of an information handling system comprising:

the plurality of EPM key assemblies including a plurality of electro-permanent magnets (EPMs) comprising:

a low-coercivity magnet;

a high-coercivity magnet; and

a magnetic field sensor to detect the magnitude of the one or more magnetic field of the EPMs; and

a calibration module to calibrate the magnitude of the one or more magnetic field of the EPMs by:

receiving a sensed magnitude value of the magnetic field associated with the plurality of the EPMs; and

adjusting the magnitude value of the magnetic field associated with each of the EPMs to a value commensurate with each other based on the established value when that magnitude value deviates from an established value by a threshold amount.

2. The EPM key assembly of claim 1 , wherein the established value is based on a user-provided actuation value to be associated with each of the EPM key assemblies.

3. The EPM key assembly of claim 1 , where the established value is within a range of a magnetic field value associated with a user-defined actuation value, the actuation value defining an actuation force used to actuate the EPM key assembly.

4. The EPM key assembly of claim 1 , where the established value is within a rang of a magnetic field value associated with an application-defined actuation value, the actuation value defining an actuation force used to actuate the EPM key assembly.

5. The EPM key assembly of claim 1 , wherein adjusting the magnitude value of the magnetic field of one or more of the EPMs comprises:

applying a current pulse at an adjusted current level to an electrically conductive wire coiled around the low-coercivity magnet.

6. The EPM key assembly of claim 1 , wherein the information handling system comprises a programmable power supply circuit and a look-up table and wherein the programmable power supply circuit accesses the look up table to determine to what extent to adjust the magnitude of current to adjust the magnetic field associated with each of the EPMs.

7. The EPM key assembly of claim 1 , wherein the information handling system comprises a programmable power supply circuit and the programmable power supply circuit receives data descriptive of which among a plurality of EPMs are to have their magnitude of magnetic field adjusted.

8. The EPM key assembly of claim 1 , wherein the information handling system comprises a programmable power supply circuit and wherein the programmable power supply circuit sends data descriptive of which among a plurality of EPMs are to have their magnitude of magnetic field adjusted to an H-bridge descriptive of which of the plurality of EPMs are to have their magnitude of magnetic field adjusted.

9. A method of calibrating an array of electro-permanent magnets (EPMs) having a low-coercivity magnet and a high-coercivity magnet associated with a plurality of EPM key assemblies, comprising:

receiving, at a processor from an array of magnetic field sensors, a sensed magnitude value of a magnetic field associated with each EPM within the array of EPMs;

determining, with the processor, when any of the plurality of EPMs has a magnitude value varying from an established value; and

adjusting, via a calibration module the magnitude value of the magnetic field associated with the EPMs having a magnitude value to within a threshold range of the established value such that any EPM key assembly actuation force differences within the array of EPMs is lessened.

10. The method of claim 9 , wherein the established value is based on a user-provided actuation value to be associated with each of the EPM key assemblies.

11. The method of claim 9 , wherein the established value is based on a detected lowest sensed magnetic field value among the array of EPMs.

12. The method of claim 9 , wherein the processor receives location data associated with an EPM among the plurality of EPMs that has a magnitude value varying from the established value.

13. The method of claim 9 , wherein adjusting the magnitude value of the magnetic field associated with the EPMs having a magnitude value that varies from the established value comprises applying an adjusted current pulse to those EPMs sufficient to saturate those EPMs toward the established value.

14. The method of claim 9 , wherein the adjusting current pulse is determined via accessing a look-up table to compare the established value to the sensed magnitude value of the EPM having a magnitude value that varies from the established value.

15. A plurality of electro-permanent magnet (EPM) key assemblies of an information handling system, each of the plurality of EPM key assemblies comprising:

a pair of scissor plates operably connected to a base contact assembly including an EPM such that each of the pair of scissor plates may rotate away from one another in the presence of downward force on a key cap;

a key cap situated atop the pair of scissor plates for actuation of the EPM key assembly;

the EPM comprising a low-coercivity magnet, and an electrically conductive wire coiled around the low-coercivity magnet, and a high coercivity magnet;

the EPM having an on state to assert a magnetic field on a flange operatively coupled to rotate with at least one scissor plate about a hinge and an off state to release the flange from the magnetic field and retract the key cap;

a magnetic field sensor to sense a magnitude of a magnetic field produced by the EPM in the on state; and

a calibration module to calibrate the magnitude of the magnetic field of the EPM by:

receiving the sensed magnitude of the magnetic field associated with each of the plurality of the EPM key assemblies; and

adjusting the magnitude value of the magnetic field associated with each of the EPM key assemblies to a range of values commensurate with an established value.

16. The EPM key assembly of claim 15 , wherein the established value is based on a user-provided actuation value to be associated with each of the EPM key assemblies.

17. The EPM key assembly of claim 15 , where the established value is about equal to a magnetic field value associated with a lowest detected actuation value to reduce key actuation value differences among a plurality of EPM key assemblies.

18. The EPM key assembly of claim 15 , where the commensurate value is about equal to a value associated with a user-defined actuation value, the actuation value defining an actuation force used to actuate the EPM key assembly.

19. The EPM key assembly of claim 15 , wherein adjusting the magnitude value of the magnetic field of the EPM comprises:

applying a current pulse in a first direction to an electrically conductive wire coiled around the low-coercivity magnet to turn the EPM to an off-state; and

applying a currently pulse at an opposite direction to the electrically conductive wire coiled around the low-coercivity magnet at an adjusted current amperage level to adjust the magnetic field value of the EPM in an on state.

20. The EPM key assembly of claim 15 , wherein the information handling system comprises a programmable power supply circuit and a look-up table, wherein the programmable power supply circuit accesses the look up table to determine to what extent to adjust the magnitude of the magnetic field associated with each of the EPMs, and wherein the programmable power supply circuit receives data descriptive of which among a plurality of EPMs are to have their magnitude of magnetic field adjusted.