TDI Image Sensor Exposure Control via Segmented Pixel Groups
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Solution Overview
Problem
Time Delayed Integration (TDI) image sensors struggle to capture clear images with a wide dynamic range, as they often fail to effectively differentiate between bright and dark portions, leading to images that do not accurately represent the human visual experience.
Innovation Solution
A TDI image sensor capable of adjusting exposure time, incorporating a pixel unit with light-blocking units and a scan controller that generates exposure control signals to control the movement of charges across line sensors, allowing for the combination of short and long exposure images using High Dynamic Range (HDR) techniques to enhance image clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single exposure time is used in TDI image sensor, then the device structure is simple, but the dynamic range is limited and cannot clearly express both bright and dark portions
Solution Approach 1:
The pixel array is divided into multiple pixel groups, where each pixel group contains pixels with different exposure times (e.g., first exposure time and second exposure time). This segmentation allows the sensor to capture both bright and dark portions effectively by combining data from pixels with different exposure durations, thereby expanding the dynamic range without requiring entirely separate imaging systems.
Solution Approach 2:
Different pixels within the same pixel group are assigned different exposure times based on their specific function. Some pixels use a first exposure time optimized for bright regions, while others use a second exposure time optimized for dark regions. This local differentiation of exposure characteristics allows each pixel to contribute optimally to its respective brightness range, achieving high dynamic range imaging.
2Adaptability or versatility
If multiple line sensors are used to capture different exposure times, then the dynamic range is expanded, but the device structure becomes more complex
Solution Approach 1:
Multiple line sensors are merged into a unified pixel array structure where different pixel groups within the same array capture images at different exposure times. The readout circuits and control logic are integrated to simultaneously or sequentially read data from all pixel groups. This merging approach achieves multi-exposure capability without requiring entirely separate sensor modules, thereby managing complexity while expanding functional versatility.
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
The solution enables the generation of clearer images by expanding the dynamic range, making bright areas brighter and dark areas darker, thereby improving image quality and accurately representing the visual experience, through the combination of short and long exposure images under the same illumination conditions.
Implementation Method 1
a pixel unit which includes a plurality of line sensors
Implementation Method 2
In an image sensor using the TDI line scan method, a plurality of line sensors is disposed in a scan direction to transmit charges accumulated in the CCD of each line to a CCD of a next line by synchronizing with movement of a scanning object
Data Source
AI summary
A TDI sensor which is capable of controlling the exposure according to the present disclosure includes a pixel unit which includes a plurality of line sensors; a light blocking unit which blocks light from being incident into some of the plurality of line sensors; a scan controller which generates an exposure control signal based on an external line trigger signal, generates an internal line trigger signal based on the external line trigger signal and the exposure control signal, and controls the movement of charges of the plurality of line sensors based on the internal line trigger signal.