Semiconductor Photosensor for Concurrent 2D and 3D Imaging
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Solution Overview
Problem
Existing methods for three-dimensional distance-measuring sensors using the time of flight (TOF) method face challenges in reducing pixel size, achieving concurrent two-dimensional and three-dimensional imaging, and accurately detecting moving objects due to increased transistor elements and inefficiencies in charge retention.
Innovation Solution
A method involving a semiconductor device with a photosensor that performs first and second irradiations for the same duration at different timings, using a high potential on a transistor gate electrode to control charge storage, allowing for concurrent two-dimensional and three-dimensional imaging without interrupting reflected light detection, and employing overlapping photodiodes for visible and infrared light to reduce pixel size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional transistors are added to the photosensor to enable TOF method, then three-dimensional distance measurement capability is improved, but pixel size increases
Solution Approach 1:
The photosensor is designed to perform multiple functions: two-dimensional imaging and three-dimensional TOF measurement, using a unified pixel architecture that shares transistors and circuitry between both functions, eliminating the need for separate dedicated circuits for each function
Solution Approach 2:
The sensor alternates between two-dimensional imaging mode and three-dimensional TOF measurement mode in periodic frame intervals, allowing the same hardware to serve both purposes by switching operational states rather than requiring simultaneous dedicated circuits for each function
2Measurement precision
If infrared light is emitted twice to obtain different detection signals for TOF, then three-dimensional imaging capability is improved, but detection continuity is disrupted
Solution Approach 1:
The infrared light emission follows a periodic pattern with alternating irradiation periods and non-irradiation periods, where reflected light is detected during the non-irradiation periods. This periodic modulation enables TOF measurement by comparing detection signals from different periods while maintaining continuous detection capability
Solution Approach 2:
The detection process continues uninterrupted by utilizing the non-irradiation periods for reflected light detection. The system maintains continuous monitoring capability by seamlessly transitioning between irradiation and detection phases without gaps in the overall detection process
3Adaptability or versatility
If frame period is switched between two-dimensional imaging and three-dimensional imaging, then both imaging modes are supported, but time difference between information acquisition occurs
Solution Approach 1:
The sensor operates in periodic alternation between two-dimensional imaging frames and three-dimensional TOF frames, with each frame type occupying specific time intervals. This periodic switching allows both imaging modes to be supported while the time difference between consecutive frames of the same type remains predictable and manageable
Solution Approach 2:
The system prepares and processes two-dimensional and three-dimensional imaging data in alternating sequence, with each frame type being fully processed before switching to the other. This preliminary completion of each imaging mode within its designated frame period minimizes temporal discrepancies between the two information streams
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
Enables accurate distance measurement and concurrent two-dimensional and three-dimensional imaging, improving charge retention and reducing pixel size, thus enhancing the performance of TOF method-based sensors.
Implementation Method 1
charge generated by photoelectric conversion performed with a photodiode
Data Source
AI summary
A method for driving a semiconductor device which enables three-dimensional imaging is provided. The method for driving the semiconductor device also enables a reduction in the size of a pixel, two-dimensional imaging concurrently with the three-dimensional imaging, and/or accurate three-dimensional imaging of a fast-moving object. The distance from a light source to an object is measured by performing a first imaging and a second imaging with respect to the timings of the first irradiation and the second irradiation, respectively. A first photosensor absorbing visible light and a second photosensor absorbing infrared light are overlapped with each other and enable the two-dimensional imaging and the three-dimensional imaging, respectively, to be performed concurrently. Adjacent photosensors detect light reflected off substantially the same point of an object, preventing a reduction in the accuracy of the three-dimensional imaging of a fast-moving object.