Credential reader having a micro power proximity detector and method of operating the credential reader

1. A credential reader comprising:

a power source; and

a micro-power proximity detector coupled with the power source, the micro-power proximity detector comprising:

an antenna configured to couple with a sense field adjacent the credential reader; and

a control circuit coupled with the antenna and with the power source, the control circuit configured to detect and register a disturbance in the sense field and configured to activate circuitry of the control circuit to read a credential when the disturbance in the sense field is detected, wherein the control circuit is configured to detect a disturbance in the sense field caused when an object having a virtual capacitance enters the sense field.

2. The credential reader of claim 1 , wherein the power source comprises one or more batteries.

3. The credential reader of claim 1 , wherein the control circuit is configured to generate the sense field with microamps of current from the power source.

4. The credential reader of claim 1 , wherein the disturbance is a change in an electrical charge of the sense field.

5. The credential reader of claim 4 , wherein the electrical charge is a net electrical charge of the sense field.

6. The credential reader of claim 1 , wherein the control circuit is configured to generate a command signal when the disturbance in the sense field is detected.

7. The credential reader of claim 6 , wherein the command signal is configured to activate the credential reader from a sleep state.

8. The credential reader of claim 1 , wherein the sense field is an electrostatic field.

9. A method comprising:

generating an electrostatic sense field adjacent to a credential reader;

detecting and registering a disturbance in the electrostatic sense field caused by a credential;

activating circuitry to generate a command signal configured to activate the credential reader from a sleep state when the disturbance is detected;

reading the credential with the credential reader when the credential reader is activated.

10. The method of claim 9 , wherein the electrostatic sense field is generated using microamps of electrical current from a power source.

11. The method of claim 10 , wherein the power source is one or more batteries.

12. The method of claim 9 , wherein the disturbance is a change in an electrical charge of the electrostatic sense field.

13. The method of claim 12 , wherein the electrical charge is a net electrical charge of the electrostatic sense field.

14. A credential reader comprising:

a printed circuit board;

an antenna formed about a perimeter of the printed circuit board and configured to couple with an electrostatic sense field, wherein the antenna is configured to propagate the sense field to extend adjacent to a surface of the credential reader, and to extend into and through a local dielectric; and

a control circuit formed on the printed circuit board, wherein the control circuit is coupled with a power source and configured to draw microamps of power from the power source to generate the electrostatic sense field, wherein the control circuit is further configured to detect and register a disturbance in the electrostatic sense field and to activate higher-power circuitry within the credential reader to read the credential when the disturbance is detected.

15. The credential reader of claim 14 , wherein the local dielectric is a material that comprises a housing of the credential reader.

16. The credential reader of claim 14 , wherein the disturbance in the electrostatic sense field is any change in a proximity environment that causes a change in a current flow through the electrostatic sense field.

17. A method comprising:

detecting a disturbance in an electrostatic sense field, which is generated by a micro-power proximity detector of a credential reader;

activating the credential reader;

attempting to read data from a credential;

if data from the credential is not received for a predetermined time interval, determining that no credential is present within the disturbed electrostatic sense field;

turning off the credential reader or placing the credential reader into a sleep state in response to determining that no credential is present; and

self-calibrating the micro-power proximity detector to account for the disturbance detected in the sense field.