Ambient infrared detection in solid state sensors
AssigneeMicron Technology, Inc.
InventorsIlia Ovsiannikov, Xuemei Zhang, Dmitri Jerdev
Life of this patent
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Abstract
A solid state imaging device includes an array of active pixels and an infrared cut filter formed over the sensor. Optionally, a slot in the infrared cut filter allows infrared illumination to reach the sensor to be detected by pixels covered by a visually opaque filter and surrounded by pixels of special types that limit charge leakage and enable high dynamic range sensing of infrared illumination. A ratio of average infrared signal to average brightness indicates an amount of infrared illumination reaching the imaging device.
Claims20
A method for detecting infrared light on a semiconductor image sensor, the method comprising:
- reading a plurality of IR light signals from a plurality of optically black IR sensitive pixels;
- generating an average IR signal by averaging the plurality of IR light signals with an analog gain;
- normalizing the average IR signal;
- reading a plurality of non-IR light signals from pixels shielded with an infrared filter;
- generating an average non-IR signal by averaging the plurality of non-IR light signals with an analog gain;
- normalizing the average non-IR signal;
- and
- generating a ratio of the average IR signal to the average non-IR signal.
A method for detecting infrared light on a semiconductor image sensor having a plurality of optically black IR-sensitive pixels that are substantially adjacent to a matrix of active pixels shielded with an infrared filter, the matrix of active pixels having red, green, and blue pixels, the method comprising:
- reading first signals from the optically black IR-sensitive pixels;
- averaging and normalizing the first signals;
- reading second signals from the matrix of active pixels, the second signals being read from active pixels that are substantially adjacent to the optically black IR-sensitive pixels;
- averaging and normalizing the second signals;
- and
- generating a ratio of the averaged and normalized first signals to the average and normalized second signals.
A method for detecting infrared light on a semiconductor image sensor having an array of active pixels filtered by an infrared filter and an area of optically black infrared-sensitive pixels that are filtered against visible light, the method comprising:
- reading signals from the optically black infrared-sensitive pixels;
- determining if the optically black infrared-sensitive pixel signals indicate infrared illumination of the optically black infrared-sensitive pixels;
- if infrared illumination is present, comparing signals from adjacent active pixels that are adjacent to the area of optically black infrared-sensitive pixels to determine a level of infrared illumination on the image sensor.
Dependencies are inferred from the claim text.