IMAGE SENSOR HAVING NONLINEAR RESPONSE

• US 20110121421A1
• Filed: 04/09/2009
• Published: 05/26/2011
• Est. Priority Date: 05/09/2008
• Status: Active Grant

• Current Assignee: Rambus Inc.
• Original Assignee: Ecole Polytechnique Federate De Lausanne Epfl
• Inventors: Sbaiz, Luciano, Susstrunk, Sabine, Charbon, Edoardo, Vetterli, Martin
• Granted Patent: US 8,633,996 B2
• Time in Patent Office: Days
• US Class Current: 257/432
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14645 Colour imagers
• CPC Class Codes: H04N 25/46 by combining or binning pixels
• CPC Class Codes: H04N 25/57 Control of the dynamic range

Abstract

In previously known imaging devices as in still and motion cameras, for example, image sensor signal response typically is linear as a function of intensity of incident light. Desirably, however, akin to the response of the human eye, response is sought to be nonlinear and, more particularly, essentially logarithmic. Preferred nonlinearity is realized in image sensor devices of the invention upon severely limiting the number of pixel states, combined with clustering of pixels into what may be termed as super-pixels.

Claims

1. An image sensor comprising a radiation-sensitive semiconductor region wherein at least a sub-region comprises a plurality of radiation-sensitive elements having a shared readout, and with each of the elements being adapted and disposed for responding to incident radiation by assuming one of a plurality of prescribed levels in correspondence with sensing a prescribed number of photons.

2. The image sensor of claim 1, wherein the plurality of prescribed levels consists of two levels.

3. The image sensor of claim 1, sensitive to visible light.

4. The image sensor of claim 1, sensitive to infrared radiation.

5. The image sensor of claim 1, comprising a CCD structure.

6. The image sensor of claim 1, comprising a CMOS structure.

7. The image sensor of claim 1, further comprising a focusing element.

8. The image sensor of claim 7, wherein the focusing element consists of an array of micro-lenses.

9. The image sensor of claim 7, wherein the focusing element comprises a pattern of essentially concentric regions of a metal layer.

10. The image sensor of claim 9, wherein the concentric regions are essentially circular.

11. The image sensor of claim 1, further comprising a filter element.

12. The image sensor of claim 11, wherein the filter element is adapted and disposed for color filtering.

13. The image sensor of claim 11, wherein the filter element is adapted and disposed for polarization filtering.

14. The image sensor of claim 1, wherein the sub-region is one of a fixed plurality of sub-regions.

15. The image sensor of claim 1, wherein the sub-region is selectable under readout control.