Image Sensor Row Grouping for Rolling Shutter Flicker Reduction
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Solution Overview
Problem
Flicker noise occurs in image sensors using a rolling shutter scheme when simultaneously reading several rows of sensor pixels, leading to reduced image quality.
Innovation Solution
The image sensor reduces the interval between average readout times of pixel units arranged in a column direction, with each pixel unit consisting of a 2×2 array, to alleviate and prevent flicker noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If several rows of sensor pixels are simultaneously read using a rolling shutter scheme, then image generation time is reduced, but flicker noise occurs
Solution Approach 1:
The patent divides the pixel array into multiple horizontal groups (first horizontal group with odd horizontal lines, second horizontal group with even horizontal lines, third horizontal group with odd horizontal lines). Each group is read out separately at different time points, segmenting the simultaneous readout process into sequential group readouts. This segmentation reduces the interval between average readout times of pixel units while preventing flicker noise by staggering the readout timing of different groups.
Solution Approach 2:
The patent implements periodic readout action by providing control signals to different horizontal groups at periodic time intervals. The row driver provides control signals at a first time point to the first horizontal group, at a second time point to the second horizontal group, and at a third time point to the third horizontal group, with equal time intervals between consecutive time points. This periodic action pattern enables simultaneous readout of multiple rows while reducing flicker noise through controlled timing.
2Object-generated harmful factors
If the interval between average readout times of pixel units is reduced, then flicker noise is minimized, but readout complexity increases
Solution Approach 1:
The patent segments the pixel array into horizontal groups based on odd and even horizontal line patterns. Each group contains n horizontal lines, and corresponding horizontal lines between groups are separated by at least a three-row interval. This segmentation strategy reduces readout complexity by organizing pixels into manageable groups while maintaining the reduced interval between average readout times necessary to minimize flicker noise.
Solution Approach 2:
The row driver employs periodic control signal provision to manage the segmented groups systematically. Control signals are provided at periodic time intervals to different horizontal groups in a repeating pattern (first group at first time point, second group at second time point, third group at third time point). This periodic action simplifies the control logic compared to arbitrary timing schemes, reducing readout complexity while achieving the desired reduced interval between average readout times.
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
This approach effectively reduces the interval between readout times of consecutively arranged pixel units, thereby minimizing flicker noise and enhancing image quality.
Implementation Method 1
The image sensor may generate an image of the object by using a photoelectric conversion device. The photoelectric conversion device reacts according to an intensity of incident light reflected from the object.
Data Source
AI summary
An image sensor including a row driver configured to provide, at a first time, a control signal to first pixels in a first group having n consecutive odd horizontal lines, provide, at a second time, the control signal to pixels in a second group having n consecutive even horizontal lines, and provide, at a third time, the control signal to pixels in a third group having n consecutive odd horizontal lines, and having a first horizontal line next to a last horizontal line of the first group, wherein each of the n horizontal lines of the first group is separated by an at least three-row interval from a corresponding one of the n horizontal lines of the second group, and a time interval between the first time point and the second time point is equal to a time interval between the second time point and the third time point.