Image Sensor Single Readout Dual Conversion Gain Merging
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Solution Overview
Problem
Dual conversion gain (DCG) technology in image sensors results in a decreased frame rate when achieving high dynamic range (HDR) images, as it requires multiple readouts with different conversion gains.
Innovation Solution
An image sensor design that applies multiple conversion gains through a single readout by arranging pixel groups with different conversion gains and using a readout circuit to generate and merge corresponding pixel signals, allowing for simultaneous output of high and low conversion gain signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple readouts with different conversion gains are performed to achieve HDR images, then image quality with rich color range is improved, but frame rate decreases
Solution Approach 1:
The patent merges multiple readout operations into a single readout by combining pixels with different conversion gains (HCG and LCG) in the same pixel array. The readout circuit simultaneously reads out signals from both HCG pixels and LCG pixels through shared signal lines, achieving HDR image quality without requiring multiple sequential readouts, thus maintaining high frame rate.
Solution Approach 2:
The pixel array is segmented into different pixel types (HCG pixels and LCG pixels) with different conversion gain characteristics. Each pixel type is optimized for specific lighting conditions, allowing the system to capture both dark and bright regions effectively within a single readout operation, resolving the contradiction between image quality and frame rate.
2Adaptability or versatility
If multiple readouts are performed to apply different conversion gains, then dynamic range is improved, but readout time increases
Solution Approach 1:
The patent combines multiple readout operations into a single simultaneous readout by designing the pixel array to include both HCG and LCG pixels that can be read out through shared signal lines. This merging approach captures the full dynamic range in one readout operation, eliminating the time loss associated with sequential multiple readouts.
Solution Approach 2:
The pixel array is pre-configured with different conversion gain pixels (HCG and LCG) in specific patterns before the readout operation. This preliminary arrangement allows the readout circuit to simultaneously access and process signals from both pixel types through shared signal lines, achieving wide dynamic range without increasing readout time.
3Adaptability or versatility
If pixel array is divided into separate HCG and LCG regions, then conversion gain flexibility is improved, but device complexity increases
Solution Approach 1:
The patent merges HCG and LCG pixels within the same pixel array region, allowing both conversion gain types to coexist and be read out through shared signal lines. This merging approach maintains conversion gain flexibility while reducing device complexity by eliminating the need for separate readout circuits and signal lines for each pixel type.
Solution Approach 2:
The readout circuit is designed with universal signal lines that can handle signals from both HCG and LCG pixels. This multi-functional readout circuit reduces device complexity by using a single readout path for both pixel types, while still maintaining the flexibility to apply different conversion gains as needed for different imaging conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Maintains a high frame rate while generating images with a rich color range by merging pixel signals from multiple conversion gains within a single readout, effectively addressing the limitations of DCG technology.
Implementation Method 1
An image sensor may sense an image of an object by using a photoelectric conversion element that reacts according to the intensity of light reflected from the object, and generate image data
Data Source
AI summary
Provided is an image sensor including: a pixel array including a plurality of pixel groups each including first pixels to which a first conversion gain is applied and second pixels to which a second conversion gain is applied; a readout circuit configured to receive a first pixel signal corresponding to the first pixels and a second pixel signal corresponding to the second pixels through a single readout with respect to each of the plurality of pixel groups, generate first image data, based on first pixel signals of the plurality of pixel groups, and generate second image data, based on second pixel signals of the plurality of pixel groups; and an image signal processor configured to generate output image data by merging the first image data and the second image data in units of a pixel group.