Image Sensor Control Circuit for Rolling Shutter Over-Saturation
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Solution Overview
Problem
Existing 3D image capture devices face challenges in maintaining image quality due to interference and irregular light emission patterns, leading to issues like over-saturation and under-exposure, which affect the accuracy of depth information.
Innovation Solution
An image capture device with a control circuit that manages a light source to continuously project light during specific intervals, ensuring consistent radiation time across all rows of a pixel array, and strategically turns off the light source to prevent over-saturation and under-exposure, while maintaining photocharge integration during off periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light source is continuously on during all pixel operations, then photocharge integration is maintained, but image over-saturation occurs
Solution Approach 1:
The light source is controlled to operate periodically: turned on during integration periods when pixels are accumulating photocharge, and turned off during readout periods when pixels are being read sequentially. This periodic switching prevents over-saturation while maintaining integration continuity, resolving the contradiction between reliable photocharge accumulation and preventing harmful over-saturation effects.
2Object-affected harmful factors
If the light source is turned off during readout operations, then over-saturation is prevented, but image under-exposure occurs
Solution Approach 1:
The light source follows a periodic on/off pattern synchronized with pixel operations: on during integration to ensure adequate illumination and exposure, off during readout to prevent over-saturation. This timing coordination ensures that under-exposure is avoided during critical integration periods while still achieving over-saturation prevention during readout phases.
Solution Approach 2:
The light source is turned on in advance before integration begins and remains on throughout the integration period, ensuring that pixels receive adequate illumination before and during photocharge accumulation. This preliminary and continuous illumination during integration prevents under-exposure, while the light is turned off before readout starts to prevent over-saturation.
3Object-affected harmful factors
If the light source is turned off during row readout, then signal noise is reduced, but depth information accuracy deteriorates
Solution Approach 1:
The light source is switched off during the readout phase when pixels are being read sequentially from the array, which reduces signal noise by preventing additional light interference during sensitive readout operations. The light is turned back on before the next integration period begins, ensuring depth information accuracy is maintained during the subsequent photocharge accumulation phase. This periodic switching optimizes both noise reduction and measurement precision at different operational stages.
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 enhances image quality by maintaining consistent light radiation and preventing signal noise reduction, thereby improving the accuracy and reliability of 3D depth information capture.
Implementation Method 1
measures a delay time between pulse light emitted from a light source which is then reflected from an object and received by the image sensor
Implementation Method 2
Each of the photoelectric conversion elements generates photocharge in proportion to the quantity of pulse light emitted by a light source and then reflected and returned from the object
Implementation Method 3
drive the light source with signals that cause the light source to continuously project light to the object (without interruption) during at least a first time interval when all rows of a frame of pixels within the array are being sequentially read
Data Source
AI summary
An image capture device includes an image sensor having an array of pixels therein, which are configured to receive light reflected from an object during an image capture time interval. A light source is provided, which is configured to project light to the object during at least a portion of the image capture time interval. A control circuit/unit is provided, which is electrically coupled to the image sensor and the light source. This control circuit is configured to drive the light source with signals that cause the light source to project light to the object without interruption during at least a first time interval when all rows of a frame of pixels within the array are being sequentially read and during a second time interval when all rows of the frame of pixels within the array are being sequentially read.