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US 8,941,527 B2Granted
Calibration in multiple slope column parallel analog-to-digital conversion for image sensors
AssigneeOmniVision Technologies, Inc.
InventorsZheng Yang, Guangbin Zhang, Yuanbao Gu
Life of this patent
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Abstract
A method of an aspect includes acquiring analog image data with a pixel array, and reading out the analog image data from the pixel array. The analog image data is converted to digital image data by performing an analog-to-digital (A/D) conversion using a multiple slope voltage ramp. At least some of the digital image data is adjusted with calibration data. Other methods, apparatus, and systems, are also disclosed.
Claims10
A method comprising:
- acquiring analog image data with a pixel array;
- reading out the analog image data from the pixel array;
- converting the analog image data to digital image data by performing an analog-to-digital (A/D) conversion using a multiple slope voltage ramp;
- and
- adjusting at least some of the digital image data with calibration data, wherein adjusting the digital image data comprises:
- accessing calibration data in a table for a first portion of the digital image data that is within a range of the table;
- and
- extrapolating calibration data in the table for a second portion of the digital image data that is not within the range of the table.
5 more elements
A method comprising:
- acquiring analog image data with a pixel array;
- reading out the analog image data from the pixel array;
- converting the analog image data to digital image data by performing an analog-to-digital (A/D) conversion using a multiple slope voltage ramp;
- obtaining calibration data, wherein obtaining the calibration data includes:
- converting a first set of analog data applied to a set of column A/D converters to a first set of digital data using a multiple slope voltage ramp, wherein converting the first set of the analog data comprises converting a first instance of a set of fixed voltages spanning a calibration voltage range applied to the set of the column A/D converters;
- and
- converting a second set of analog data applied to the set of column A/D converters to a second set of digital data using a single slope voltage ramp, wherein converting the second set of the analog data comprises converting a second instance of the same set of fixed voltages spanning the calibration voltage range applied to the set of the column A/D converters;
- and
- adjusting at least some of the digital image data with the calibration data.
6 more elements
A method comprising:
- acquiring analog image data with a pixel array;
- reading out the analog image data from the pixel array;
- converting the analog image data to digital image data by performing an analog-to-digital (A/D) conversion using a multiple slope voltage ramp;
- obtaining calibration data, wherein obtaining the calibration data includes:
- converting a first set of analog data applied to a set of column A/D converters to a first set of digital data using a multiple slope voltage ramp;
- and
- converting a second set of analog data applied to the set of column A/D converters to a second set of digital data using a single slope voltage ramp;
- and
- adjusting at least some of the digital image data with the calibration data,
- wherein obtaining the calibration data comprises obtaining the calibration data during a time when readout signals are applied to two non-imaging rows of pixels of the pixel array, wherein the multiple slope voltage ramp is used when the readout signals are applied to a first of the two non-imaging rows of pixels, and wherein the single slope voltage ramp is used when the readout signals are applied to a second of the two non-imaging rows of pixels.
7 more elements
Dependencies are inferred from the claim text.