Indirect Time of Flight Sensor Parallel Pixel Architecture
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Solution Overview
Problem
Conventional indirect Time of Flight (ToF) sensors with small form factors face challenges in simultaneously projecting structured light patterns and flood illumination, leading to errors in depth determination, especially with dynamic scenes due to motion blur and increased power consumption.
Innovation Solution
An indirect ToF sensor with a parallel pixel architecture is integrated into a depth determination assembly, featuring multiple pixels with dedicated compute circuitry configured to detect light modulated at different frequencies, allowing concurrent detection and asynchronous depth determination, which mitigates motion blur and reduces power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional indirect ToF sensors use single frequency light modulation, then device complexity is reduced, but depth determination accuracy deteriorates in dynamic scenes due to motion blur
Solution Approach 1:
The sensor array is segmented into multiple pixel types (first pixels detecting first frequency, second pixels detecting second frequency) that operate independently and in parallel. Each pixel type is dedicated to detecting light modulated at a specific frequency, allowing simultaneous multi-frequency depth measurement without requiring complex per-pixel frequency switching mechanisms.
Solution Approach 2:
The system changes the modulation frequency parameter of the illuminator to emit light at different frequencies (first frequency and second frequency) that correspond to different depth ranges. By adjusting this parameter, the system can disambiguate depth information and reduce motion blur effects without increasing mechanical complexity.
2Measurement precision
If conventional sensors sequentially capture multiple frequencies, then depth disambiguation is achieved, but productivity decreases due to increased capture time and motion blur
Solution Approach 1:
The pixel array is divided into specialized segments (first pixels and second pixels) that are spatially distributed and functionally dedicated to different frequency bands. This segmentation enables simultaneous capture of multiple frequency signals in a single frame, eliminating the need for sequential capture and reducing motion blur.
Solution Approach 2:
The sensor performs continuous depth measurement at multiple frequencies simultaneously through parallel pixel operation, rather than interrupting measurement for frequency switching. This continuous multi-frequency detection maintains high frame rates and reduces motion artifacts.
3Adaptability or versatility
If conventional ToF systems use flood illumination only, then device complexity is reduced, but adaptability deteriorates as structured light patterns cannot be projected
Solution Approach 1:
The illuminator is designed with multi-functionality to perform both flood illumination and structured light pattern projection using the same light source and optical components. By modulating the light at different frequencies and using the sensor's multi-frequency detection capability, the system achieves versatile illumination without requiring separate illumination systems.
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 faster and more accurate depth determination by allowing each pixel to use information from adjacent pixels detecting different frequencies, reducing motion blur and power consumption while maintaining accurate depth information in dynamic scenes.
Implementation Method 1
The compute layer is configured to determine depth information for the local area using an indirect ToF technique and one or both of the detected light that has the first modulation frequency and the detected light that has the second modulation frequency
Implementation Method 2
The plurality of pixels includes a first group of pixels that is configured to detect light from a local area that has a first modulation frequency, and a second group of pixels that is configured to detect light from the local area that has a second modulation frequency
Data Source
AI summary
A sensor includes a plurality of pixels that each have dedicated compute circuitry within a compute layer. The plurality of pixels includes a first group of pixels and a second group of pixels. The first group of pixels is configured to detect light from a local area that has a first modulation frequency. The second group of pixels is configured to detect light from the local area that has a second modulation frequency. The compute layer is positioned below the plurality of pixels, and includes the compute circuitry for each of the plurality of pixels. The compute layer is configured to determine depth information for the local area using an indirect time-of-flight technique and one or both of the detected light that has the first modulation frequency and the detected light that has the second modulation frequency.