INFRARED SENSING DEVICES AND METHODS

• US 20170016762A1
• Filed: 07/15/2016
• Published: 01/19/2017
• Est. Priority Date: 07/17/2015
• Status: Active Grant

• Current Assignee: Melexis Technologies NV (Sensinnovat BVBA)
• Original Assignee: Melexis Technologies NV (Sensinnovat BVBA)
• Inventors: VANROYE, Karel, REEKMANS, Stijn, VAN BUGGENHOUT, Carl, MAES, Ben
• Granted Patent: US 9,989,405 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01J 1/0252 Constructional arrangements for compensating for fluctuations caused by, e.g. temperature, or using cooling or temperature stabilization of parts of the device; Controlling the atmosphere inside a photometer; Purge systems, cleaning devices protection against electromagnetic interferences G01J2001/0276
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G01J 2005/066 Differential arrangement, i.e. sensitive/not sensitive
• CPC Class Codes: G01J 5/06 Arrangements for eliminating effects of disturbing radiation; Arrangements for compensating changes in sensitivity for adjusting of solid angle of collected radiation G01J5/07; means for wavelength selection G01J5/0801
• CPC Class Codes: G01J 5/064 Ambient temperature sensor; Housing temperature sensor; Constructional details thereof
• CPC Class Codes: G01J 5/12 using thermoelectric elements, e.g. thermocouples

Abstract

An infrared sensor assembly for sensing infrared radiation from an object is disclosed. The infrared sensor assembly comprises a sensor array comprising a plurality of sensing elements, provided on or embedded in a substrate extending in a substrate plane. The sensor array comprises at least two infrared sensing elements, each infrared sensing element having a radiation responsive element providing a proportionate electrical signal in response to infrared radiation incident thereto and at least two blind sensing elements, at least one blind sensing element being interspersed among the at least two sensing elements, each blind sensing element being shielded from incident infrared radiation from the object and providing a proportionate electrical signal in response to parasitic thermal fluxes. The output of the sensor array is a function of the infrared sensing elements and of the blind sensing elements such that parasitic thermal fluxes are at least partly compensated for.

Claims

1. An infrared sensor assembly for sensing infrared radiation from an object, the infrared sensor assembly comprising:

a sensor array comprising a plurality of sensing elements, provided on or embedded in a substrate extending in a substrate plane, wherein the sensor array comprises;

at least two infrared sensing elements, each infrared sensing element having a radiation responsive element providing a proportionate electrical signal in response to infrared radiation incident thereto;

at least two blind sensing elements, at least one blind sensing element being interspersed among the at least two sensing elements, each blind sensing element being shielded from incident infrared radiation of the object and providing a proportionate electrical signal in response to parasitic thermal fluxes,

wherein an output of the sensor array is a function of a sum of the signals of the infrared sensing elements and a sum of the signals of the blind sensing elements such that parasitic thermal fluxes are at least partly compensated for.

2. The infrared sensor assembly according to claim 1, whereby the output of the sensor array is a subtractive function of a sum of the signals of the plurality of the infrared sensing elements and a sum of the signals of the plurality of blind sensing elements such that at least linear and/or non-linear thermal gradients over the sensor array are cancelled.

3. The infrared sensor assembly according to claim 2, wherein said subtractive function corresponds with a sum of the signals of the plurality of the infrared sensing elements minus a multiplication of a proportionality factor and a sum of the signals of the plurality of blind sensing elements and/or wherein said subtractive function is achieved by placing the sensors in circuit according to an anti-series schematic.

4. The infrared sensor assembly according to claim 1, wherein any of said sum of the signals of the plurality of the infrared sensing elements and/or said sum of the signals of the plurality of blind sensing elements is a weighted sum wherein for each of the pixels a weighing factor is taken into account.

5. The infrared sensor assembly according to claim 1, wherein the blind sensing elements and the infrared sensing elements are configured for having a full field of view corresponding with the field of view of the infrared sensor assembly.

6. The infrared sensor assembly according to claim 1, wherein the center of the sensor array is matched with the center of a cap covering the sensor array or with respect to an external environment inducing non-linear thermal gradients.

7. The infrared sensor assembly according to claim 1, further comprising a processor for processing of the electrical signal output of the infrared sensing elements and of the blind sensing elements, thus cancelling the signal distortion caused by thermal gradients of the sensor array, and/or further comprising a processor programmed for subtractive processing of the electrical signal output of the plurality of the infrared sensor elements of the sensor array together with the output of the plurality of blind sensor elements of the sensor array, thus cancelling the signal distortion caused by thermal gradients of the sensor array.

8. The infrared sensor assembly according to claim 1, further comprising means for sampling and digitizing the output of the plurality of infrared sensing elements of the sensor array together with the plurality of blind infrared sensing elements of the sensor array and/or wherein parasitic thermal fluxes can be considered as a convolution of thermal gradients over the sensor array and wherein for each infrared sensing elements a blind sensing element is positioned on an isotherm in the pixel array, the isotherm being corresponding with one of the thermal gradients in the convoluted thermal gradients.

9. The infrared sensor assembly according to claim 1, wherein each row and/or each column of the sensor array comprises at least one blind sensing element.

10. The infrared sensor assembly according to claim 1, wherein the sensor array comprises a same amount of infrared sensing elements and blind infrared sensing elements and/or wherein each row and/or each column of the sensor array comprises a same amount of infrared sensor elements and blind infrared sensor elements, and the sensor elements are arranged in a checkerboard arrangement.

11. The infrared sensor assembly according to claim 1, wherein the sensor array is a 2×

2 sensor array wherein the main diagonal elements of the sensor array only comprise blind sensing elements.

12. The infrared sensor assembly according to claim 1, wherein each corner of the sensor array comprises a blind sensing element and whereby the sensor array further comprises at least one blind sensing element interspersed in between the at least two infrared sensing elements and/or wherein the sensor array comprises a same amount of rows and columns.

13. The infrared sensor assembly according to claim 1, further comprising a scanning shift register for selecting a row of the sensor array to be read out.

14. The infrared sensor assembly according to claim 1, wherein the infrared sensing elements and blind infrared sensing elements each have a same layout.

15. The infrared sensor assembly according to claim 1, wherein channels are provided between the infrared sensor elements and blind infrared sensor elements of the sensor array.

16. An infrared sensor assembly comprising a sensor array for providing an image signal of a scene, the sensor array comprising a plurality of infrared sensing elements and blind infrared sensing elements, wherein the sensor array comprises channels which are provided between the plurality of infrared sensor elements and blind infrared sensor elements.

17. A method for sensing an infrared signal from an object using an array comprising a plurality of infrared sensing elements, the method comprising:

sensing a signal using at least two infrared sensing elements comprising a radiation response element providing a proportionate electrical signal in response to infrared radiation incident thereto;

sensing a signal using at least two blind sensing elements interspersed among the at least two sensing elements, each blind sensing element being shielded from incident infrared signal from the object, providing a proportionate electrical signal in response to parasitic thermal fluxes

processing the signals such that the output of the sensor array is a function of a sum of signals of the infrared sensing elements and a sum of the signals of the blind sensing elements such that parasitic thermal fluxes are at least partly compensated for.

18. A method according to claim 17, whereby said processing comprises processing comprises processing the signals such that the output of the sensor array is a subtractive function of a sum of the signals of the plurality of the infrared sensing elements and a sum of the signals of the plurality of blind sensing elements such that at least linear and/or non-linear thermal gradients over the sensor array are cancelled.

19. The method according to claim 18, wherein said processing comprises deriving the output as a subtractive function corresponding with a sum of the signals of the plurality of the infrared sensing elements minus a multiplication of a proportionality factor and a sum of the signals of the plurality of blind sensing elements.

20. The method according to claim 19, wherein said processing comprises deriving the output as a subtractive function wherein any of said sum of the signals of the plurality of the infrared sensing elements and/or said sum of the signals of the plurality of blind sensing elements is a weighted sum wherein for each of the pixels a weighing factor is taken into account.