Image Sensor Adaptive Power Reduction via Rolling Shutter Control
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Solution Overview
Problem
Conventional image sensors face challenges in effectively reducing power consumption due to insufficient blanking periods, which affects their performance, especially in normal light conditions.
Innovation Solution
An adaptive method is implemented in the image sensor that compares integration time and frame height to generate a power-saving signal, allowing non-essential circuitry to be turned off during extended blanking periods without causing banding issues, by utilizing an electronic rolling shutter to reset and read pixels row by row.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the readout circuit is turned off during the blanking period to save power, then power consumption is reduced, but the readout circuit cannot recover in time under normal light conditions, affecting image sensor performance
Solution Approach 1:
The patent applies dynamics by making the readout circuit's operational state adjustable rather than fixed. The circuit can dynamically switch between fully operational, partially operational, and powered-off states based on real-time conditions. This is achieved through control logic that monitors integration time and frame height parameters, enabling the system to adapt its power consumption and performance characteristics to match actual operating requirements, thus resolving the contradiction between power saving and performance reliability.
2Measurement precision
If the integration time is extended to capture more signal charge in low light conditions, then image quality improves, but the blanking period becomes insufficient, preventing effective power saving
Solution Approach 1:
The patent applies parameter changes by introducing a partially operational state for the readout circuit during the blanking period. Instead of binary on/off control, the system adjusts operational parameters such as clock frequency or circuit activity level based on the relationship between integration time and frame height. When integration time is extended (I > H), the control logic enables a intermediate operational mode that consumes less power than full operation but more than complete shutdown, allowing the system to maintain adequate signal charge collection while still achieving some power saving during extended integration periods.
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 power consumption without incurring banding issues, ensuring the image sensor's performance is maintained across varying light conditions by optimizing power usage during extended blanking periods.
Implementation Method 1
the integration time represents a time required to collect signal charge from a photo sensor of the pixel in response to illumination of an incident light
Data Source
AI summary
A method of adaptively reducing power consumption in an image sensor includes using an electronic rolling shutter to reset pixels of the image sensor row by row. Signal charges are read out from the pixels row by row, followed by obtaining an integration time and a frame height. A power-saving signal is generated when the integration time is substantially greater than the frame height, and at least a circuitry that is not required to operate during an active period of the power-saving signal is turned off.