Intensity-Normalized Image Sensor Dynamic Integration Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image sensors face challenges in handling large dynamic ranges due to the variation in light intensity, which leads to issues like motion blurring and increased on-chip footprint, making it difficult to capture images in low-light or high-light conditions effectively.
Innovation Solution
The image sensor employs a pixel architecture with an all-pass intensity filter and a pre-defined filter pattern, where the transfer gates for all pixels in a pattern are controlled by a shared signal, allowing for dynamic integration time based on charge accumulation, and uses a ratio-to-digital converter to digitize charges relative to an intensity pixel, reducing the need for large front-end electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple integration times are used to increase effective dynamic range, then the dynamic range is improved, but motion blurring occurs in dynamic scenes
Solution Approach 1:
The patent implements dynamic integration time control where the integration time is adjusted based on the intensity signal from intensity pixels. Bright pixels use shorter integration times while dark pixels use longer integration times, allowing the system to adapt to local intensity conditions and avoid motion blurring in bright regions while maintaining sensitivity in dark regions.
Solution Approach 2:
The patent applies different integration times to different spatial regions based on local intensity conditions. Each pixel's integration time is determined by its local intensity measurement, allowing bright regions to use short integration times and dark regions to use long integration times, thereby resolving motion blurring locally where it occurs.
2Adaptability or versatility
If sophisticated electronic circuits are used to handle large dynamic range, then the dynamic range handling capability is improved, but the on-chip footprint increases
Solution Approach 1:
The patent extracts the dynamic range adjustment function from complex electronic circuits and implements it through optical intensity measurement and timing control. By using intensity pixels to measure local intensity and controlling integration time based on these measurements, the system achieves large dynamic range handling without requiring sophisticated on-chip electronics for each pixel.
Solution Approach 2:
The patent replaces complex electronic dynamic range adjustment circuits with a simpler system based on optical intensity measurement and time control. Instead of using electronic circuits to handle dynamic range, the system uses the timing of charge transfer controlled by intensity measurements, thereby reducing on-chip footprint while maintaining dynamic range capability.
3Adaptability or versatility
If multiple integration periods are used to accumulate charge, then the dynamic range is improved, but the device complexity increases
Solution Approach 1:
The patent uses periodic integration periods controlled by transfer gate timing signals. The integration time is determined by the duration between transfer gate opening events, which are triggered based on intensity pixel measurements. This periodic action with variable period lengths enables dynamic range adjustment without requiring multiple separate integration circuits.
4Device complexity
If fixed integration time is used, then the device complexity is reduced, but the ability to capture images in low-light or high-light conditions deteriorates
Solution Approach 1:
The patent changes the integration time parameter dynamically based on local intensity conditions. By adjusting the integration time from short to long durations depending on whether pixels are bright or dark, the system maintains low device complexity while achieving the ability to capture images across a wide range of lighting 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
This approach allows for effective capture of images across a wide dynamic range without motion blurring, while reducing the complexity and size of the front-end electronics, enhancing low-light sensitivity and image quality.
Implementation Method 1
the corresponding filter of certain pixels includes an all-pass, or intensity, optical filter (I) by which the intensity of the optical signal received by the pixels can be ascertained
Implementation Method 2
a photosensitive part to convert the light to electric charge
Data Source
AI summary
An image sensor has a plurality of rows and columns of pixels, including RGB and bandpass I filters in a predetermined pattern shifted between adjacent columns so that none of the RGBI filters is adjacent the same type of filter. Each pixel includes a photodiode, a transfer gate and a floating diffusion. The transfer gate for all pixels in a pattern is controlled by the same signal, which can be a separate synchronous control signal controlled based on a predefined integration period or an asynchronous signal generated internally by the bandpass filter I and that is compared to a predefined voltage level indicative of a predetermined intensity at filter I. Upon activation of either signal, the integration period for the pixels ends and the charge on the floating diffusion for the R, G and B pixels is digitized in relation to the bandpass pixel I using a ratio-to-digital converter.