Indirect Time-of-Flight Sensor With Sequential Area Illumination
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Solution Overview
Problem
Indirect time of flight sensors suffer from inefficiencies in power consumption and signal-to-noise ratio due to simultaneous illumination and reading of the entire scene, leading to suboptimal performance.
Innovation Solution
The sensor is designed to illuminate and read areas of the scene sequentially, using a matrix of pixels with controlled charge transfer and illumination devices to optimize power usage and enhance signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the entire scene is illuminated and read simultaneously, then the coverage area is maximized, but power consumption increases and signal-to-noise ratio deteriorates
Solution Approach 1:
The sensor divides the scene into multiple areas and the pixel matrix into corresponding regions. Instead of illuminating and reading the entire scene simultaneously, the system segments the operation into sequential blocks, where each block corresponds to a specific area of the scene and its associated pixel region. This segmentation allows the illumination device to illuminate only one area at a time while the corresponding pixels perform charge transfer and reading operations, thereby reducing overall power consumption while maintaining complete scene coverage through sequential processing.
2Area of stationary object
If the entire scene is illuminated and read simultaneously, then the coverage area is maximized, but signal-to-noise ratio deteriorates
Solution Approach 1:
The system segments the scene into discrete areas and processes them sequentially rather than simultaneously. By dividing the pixel matrix into regions that correspond to these scene areas, the sensor can concentrate illumination and reading operations on specific segments, improving the signal-to-noise ratio for each segment while maintaining overall scene coverage through sequential processing of all segments.
Solution Approach 2:
The sensor employs periodic sequential operations where different areas of the scene are illuminated and read in alternating time periods. This periodic action allows the system to cycle through various scene regions, performing charge transfer and reading operations during illumination periods and minimizing read operations during non-illumination periods, thereby enhancing signal quality by reducing noise from simultaneous operations.
3Speed
If charge transfer is performed for all pixels simultaneously, then the processing speed is maximized, but power consumption increases
Solution Approach 1:
The pixel matrix is divided into multiple regions corresponding to different scene areas. Instead of performing charge transfer simultaneously for all pixels, the system segments the charge transfer operation to occur only in pixels corresponding to the currently illuminated scene area. This segmented approach reduces the number of active charge transfer devices at any given time, lowering power consumption while maintaining processing speed through efficient sequential coordination of the segmented regions.
Solution Approach 2:
The system dynamically activates or deactivates charge transfer devices based on the current operational state. When a particular scene area is being illuminated, only the corresponding pixel regions have their charge transfer devices active; for other areas, the charge transfer devices remain inactive. This dynamic control allows the system to maintain high processing speed for the active region while significantly reducing overall power consumption by keeping inactive regions in a low-power state.
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 reduces power consumption and increases the signal-to-noise ratio by focusing illumination and reading on specific areas, improving the overall performance of the sensor.
Implementation Method 1
a photoconversion region and at least two sets each comprising a charges storage region and a controllable transfer device for transferring charges from the photoconversion region towards said storage region
Implementation Method 2
an illumination device for illuminating a scene to capture
Data Source
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Figure 5~6
AI summary
The present disclosure relates to an indirect time of flight sensor comprising: a matrix (200) of pixels (1) each comprising at least two controllable transfer devices (TGmeml; TGmem2); first conductive lines (204) transmitting first control signals to the transfer devices (TGmeml; TGmem2); a first circuit (CTRL1) providing the first signals; and a device (205) for illuminating a scene to capture, wherein: the scene is divided in first areas (S1, S2, S3, S4); the device (205) illuminates successively each first area; the matrix (200) is divided in second areas (M1, M2, M3, M4); the matrix (200) and of the illumination device (205) are disposed such that each first area (S1, S2, S3, S4) corresponds to one second area (M1, M2, M3, M4); and the first circuit (CTRL1) provides different first signals (TG1, TG2) to the different second areas (M1, M2, M3, M4).