Apparatus and method for eliminating artifacts in active pixel sensor (APS) imagers

• US 20090015700A1
• Filed: 06/27/2008
• Published: 01/15/2009
• Est. Priority Date: 03/09/1999
• Status: Active Grant

• Current Assignee: Yibing Michelle Wang
• Original Assignee: Yibing Michelle Wang
• Inventors: Wang, Yibing (Michelle)
• Granted Patent: US 8,063,965 B2
• Time in Patent Office: Days
• US Class Current: 348/308
• CPC Class Codes: H04N 23/76 by influencing the image signals
• CPC Class Codes: H04N 25/627 Detection or reduction of inverted contrast or eclipsing effects
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/78 Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters

Abstract

An active pixel sensor (APS) that includes circuitry to eliminate artifacts in digital images. The APS includes a comparator for comparing a signal level from a pixel to an adjusted saturation voltage to determine if the pixel is saturated. If the pixel is saturated, the signal output from the pixel is replaced with an analog voltage having a maximum value corresponding to a brightest pixel in the image.

Claims

1-15. -15. (canceled)

16. An image snesor comprising:

a photodetector for outputting an output level indicative of incident light;

a sampling circuit that samples the generated charge and provides a readout value that indicates the amount of incident light; and

a saturation circuit that substitutes an adjusted maximum voltage for the readout value when the readout value exceeds a maximum level.

17. The image sensor of claim 16, further comprising a calculating circuit for calculating a difference voltage from the output level and reset level.

18. The image sensor of claim 17, wherein the saturation circuit ouputs the difference voltage when the output lvel exceeds the adjusted maximum voltage.

19. The image sensor of claim 16, further comprising an analog-to-digital converter electrically for converting the adjusted maximum voltage to a maximum digital value.

20. The image sensor of claim 16, wherein the adjusted saturation voltage is greater than a voltage at which the photodetector saturates.