Integrated circuit infrared sensor and associated methods

• US 20060062439A1
• Filed: 09/13/2005
• Published: 03/23/2006
• Est. Priority Date: 09/05/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: AuthenTec Incorporated (Apple Inc.)
• Inventors: Setlak, Dale R.
• Granted Patent: US 7,351,974 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing

Abstract

An integrated circuit sensor may include at least one infrared sensing element on a substrate. The sensing element may include at least one first thermocouple junction heated from infrared radiation, at least one second thermocouple junction connected to the first thermocouple junction, and a controller. The controller may detect a temperature difference between the first and second thermocouple junctions, and may pump heat therebetween to drive the detected temperature difference toward a desired value. The controller may also generate an infrared radiation output signal based upon the heat pumped. The controller may alternatingly switch between detecting the temperature difference and pumping heat, and the desired temperature difference may be zero. The sensor is readily made using integrated circuit processing technology, and may, for example, be used in many types of applications, such as biometric identification by including biometric processing circuitry connected to the controller.

Claims

1. An integrated circuit sensor comprising:

a substrate; and

at least one infrared sensing element on said substrate and comprising

at least one first thermocouple junction heated from infrared radiation,

at least one second thermocouple junction connected to said at least one first thermocouple junction, and

a controller detecting a temperature difference between said at least one first thermocouple junction and said at least one second thermocouple junction, and pumping heat between said at least one first thermocouple junction and at least one second thermocouple junction to drive the detected temperature difference toward a desired value,

said controller also generating an infrared radiation output signal based upon the heat pumped.

2. The integrated circuit sensor according to claim 1 wherein said controller alternatingly switches between detecting the temperature difference and pumping heat.

3. The integrated circuit sensor according to claim 1 wherein the desired temperature difference is zero.

4. The integrated circuit sensor according to claim 1 further comprising biometric processing circuitry connected to said controller.

5. The integrated circuit sensor according to claim 1 wherein said controller comprises:

a detector for detecting a voltage between said at least one first thermocouple junction and said at least one second thermocouple junction indicative of a temperature difference therebetween; and

a driver for driving current through said at least one first thermocouple junction and said at least one second thermocouple junction to pump heat therebetween.

6. The integrated circuit sensor according to claim 5 wherein said controller further comprises:

a switcher for alternatingly switching said at least one first thermocouple junction and said at least one second thermocouple junction between said detector and said driver;

a regulator to operate said driver responsive to said detector so that the detected voltage is driven toward zero; and

a reader connected to said driver for determining the drive current provided thereby indicative of the heat pumped.

7. The integrated circuit sensor according to claim 1 wherein said at least one second thermocouple junction is thermally coupled to said substrate via a lower thermal resistance than said at least one first thermocouple junction.

8. The integrated circuit sensor according to claim 1 further comprising at least one solid layer between said substrate and said at least one first thermocouple junction so that there is no void therebetween.

9. The integrated circuit sensor according to claim 8 and wherein said at least one solid layer comprises at least one oxide layer.

10. The integrated circuit sensor according to claim 1 wherein said at least one infrared sensing element comprises a plurality thereof.

11. The integrated circuit sensor according to claim 10 wherein said second thermocouple junctions of said plurality of infrared sensing elements are thermally coupled to said substrate.

12. The integrated circuit sensor according to claim 1 wherein said at least one infrared sensing element further comprises an infrared radiation antenna thermally coupled to said at least one first thermocouple junction.

13. The integrated circuit sensor according to claim 1 wherein said at least one first thermocouple junction comprises a plurality thereof connected together;

and wherein said at least one second thermocouple junction comprises a plurality thereof connected together.

14. An integrated circuit sensor comprising:

a substrate; and

a plurality of infrared sensing elements on said substrate, each infrared sensing element comprising

at least one first thermocouple junction heated from infrared radiation,

at least one solid layer between said substrate and said at least one first thermocouple junction so that there is no void therebetween,

at least one second thermocouple junction connected to said at least one first thermocouple junction, and

a controller alternatingly detecting a temperature difference between said at least one first thermocouple junction and said at least one second thermocouple junction, and pumping heat between said at least one first thermocouple junction and at least one second thermocouple junction to drive the detected temperature difference toward a desired value.

15. The integrated circuit sensor according to claim 14 wherein the desired temperature difference is zero.

16. The integrated circuit sensor according to claim 14 wherein said controller also generates an infrared radiation output signal.

17. The integrated circuit sensor according to claim 14 further comprising biometric processing circuitry connected to said controller.

18. The integrated circuit sensor according to claim 14 wherein said controller comprises:

a detector for detecting a voltage between said at least one first thermocouple junction and said at least one second thermocouple junction indicative of a temperature difference therebetween;

a driver for driving current through said at least one first thermocouple junction and said at least one second thermocouple junction to pump heat therebetween;

a switcher for alternatingly switching said at least one first thermocouple junction and said at least one second thermocouple junction between said detector and said driver;

a regulator to operate said driver responsive to said detector so that the detected voltage is driven toward zero; and

a reader connected to said driver for determining the drive current provided thereby indicative of the heat pumped.

19. The integrated circuit sensor according to claim 14 and wherein said at least one solid layer comprises at least one oxide layer.

20. The integrated circuit sensor according to claim 14 wherein said second thermocouple junctions of said plurality of infrared sensing elements are thermally coupled to said substrate.

21. The integrated circuit sensor according to claim 14 wherein each of said infrared sensing elements further comprises an infrared radiation antenna thermally coupled to said at least one first thermocouple junction.

22. The integrated circuit sensor according to claim 14 wherein said at least one first thermocouple junction comprises a plurality thereof connected together;

and wherein said at least one second thermocouple junction comprises a plurality thereof connected together.

23. An integrated circuit biometric sensor comprising:

a substrate;

a plurality of infrared sensing elements on said substrate, each infrared sensing element comprising

at least one first thermocouple junction heated from infrared radiation,

at least one second thermocouple junction connected to said at least one first thermocouple junction, and

a controller detecting a temperature difference between said at least one first thermocouple junction and said at least one second thermocouple junction, and pumping heat between said at least one first thermocouple junction and at least one second thermocouple junction to drive the detected temperature difference toward a desired value,

said controller also generating an infrared radiation output signal based upon the heat pumped; and

biometric processing circuitry connected to said controllers.

24. The integrated circuit biometric sensor according to claim 23 wherein said controller comprises:

a detector for detecting a voltage between said at least one first thermocouple junction and said at least one second thermocouple junction indicative of a temperature difference therebetween;

a driver for driving current through said at least one first thermocouple junction and said at least one second thermocouple junction to pump heat therebetween;

a switcher for alternatingly switching said at least one first thermocouple junction and said at least one second thermocouple junction between said detector and said driver;

a regulator to operate said driver responsive to said detector so that the detected voltage is driven toward zero; and

a reader connected to said driver for determining the drive current provided thereby indicative of the heat pumped.

25. The integrated circuit biometric sensor according to claim 23 wherein said second thermocouple junctions of said plurality of infrared sensing elements are thermally coupled to said substrate.

26. The integrated circuit biometric sensor according to claim 23 wherein each of said infrared sensing elements further comprises an infrared radiation antenna thermally coupled to said at least one first thermocouple junction.

27. An integrated circuit sensor comprising:

a substrate; and

at least one heat sensing element on said substrate and comprising

at least one first thermocouple junction,

at least one second thermocouple junction connected to said at least one first thermocouple junction, and

a controller detecting a temperature difference between said at least one first thermocouple junction and said at least one second thermocouple junction, and pumping heat between said at least one first thermocouple junction and at least one second thermocouple junction to drive the detected temperature difference toward a desired value,

said controller also generating a heat output signal based upon the heat pumped.

28. The integrated circuit sensor according to claim 27 wherein said controller alternatingly switches between detecting the temperature difference and pumping heat;

and wherein the desired temperature difference is zero.

29. The integrated circuit sensor according to claim 27 further comprising biometric processing circuitry connected to said controller.

30. The integrated circuit sensor according to claim 27 wherein said controller comprises:

a detector for detecting a voltage between said at least one first thermocouple junction and said at least one second thermocouple junction indicative of a temperature difference therebetween;

a driver for driving current through said at least one first thermocouple junction and said at least one second thermocouple junction to pump heat therebetween;

a switcher for alternatingly switching said at least one first thermocouple junction and said at least one second thermocouple junction between said detector and said driver;

a regulator to operate said driver responsive to said detector so that the detected voltage is driven toward zero; and

a reader connected to said driver for determining the drive current provided thereby indicative of the heat pumped.

31. A method for infrared sensing using an integrated circuit sensor comprising a substrate and at least one infrared sensing element on the substrate, the at least one infrared sensing element comprising at least one first thermocouple junction heated from infrared radiation, and at least one second thermocouple junction connected to the at least one first thermocouple junction, the method comprising:

detecting a temperature difference between the at least one first thermocouple junction and the at least one second thermocouple junction;

pumping heat between the at least one first thermocouple junction and at least one second thermocouple junction to drive the detected temperature difference toward a desired value; and

generating an infrared radiation output signal based upon the heat pumped.

32. The method according to claim 31 further comprising alternatingly switching between detecting the temperature difference and pumping heat;

and wherein the desired temperature difference is zero.

33. The method according to claim 31 further comprising processing the infrared radiation output signal for biometric identification.

34. The method according to claim 31 wherein detecting comprises detecting a voltage between the at least one first thermocouple junction and the at least one second thermocouple junction indicative of a temperature difference therebetween;

wherein pumping heat comprises driving current through the at least one first thermocouple junction and the at least one second thermocouple junction to pump heat therebetween; and

wherein generating comprises determining the drive current provided thereby indicative of the heat pumped.

35. The method according to claim 31 wherein the integrated circuit sensor further comprises at least one solid layer between the substrate and the at least one first thermocouple junction so that there is no void therebetween.

36. The method according to claim 31 wherein the at least one infrared sensing element further comprises an infrared radiation antenna thermally coupled to the at least one first thermocouple junction.