ToF Sensor Wavelength Filtering Simultaneous Depth Sensing
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Solution Overview
Problem
Existing time-of-flight 3D depth sensing technologies face challenges with long sampling times, leading to false sampling and depth signal errors when objects move in the scene.
Innovation Solution
A time-of-flight sensing system and method utilizing two light sources emitting light beams of different wavelengths, which are filtered to allow only one wavelength to reach each type of sensing pixel, allowing simultaneous sensing and reducing sampling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four samples are taken with 90-degree phase steps for iToF measurement, then measurement completeness is improved, but sampling time increases causing false sampling errors
Solution Approach 1:
The patent divides the sensing array into multiple sub-arrays, where each sub-array captures a specific phase component of the modulated light signal. By segmenting the sensing function across spatially separated sub-arrays, the system can simultaneously obtain multiple phase samples without increasing temporal sampling intervals, thus resolving the contradiction between measurement completeness and sampling time.
Solution Approach 2:
The patent transitions from temporal sampling (taking multiple samples at different time points) to spatial sampling (taking multiple samples simultaneously across different sub-arrays). This dimensional change allows the system to obtain complete phase information without extending the sampling time, eliminating false sampling errors caused by object movement during the measurement process.
2Measurement precision
If multiple light beams of different wavelengths are emitted sequentially, then wavelength separation for filtering is improved, but measurement time increases
Solution Approach 1:
The patent combines multiple light sources emitting different wavelengths into a single optical path that reaches the sensing array simultaneously. By merging the light beams spatially and temporally, the system achieves wavelength discrimination through spectral filtering without the time penalty of sequential emission, thus resolving the contradiction between wavelength separation and measurement time.
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 proposed solution significantly shortens sampling time and improves the accuracy of depth signals by enabling simultaneous detection of light beams with different wavelengths, thereby reducing errors caused by object movement.
Implementation Method 1
The filter layer has a plurality of first filter patterns respectively overlapping the first sensing pixels and a plurality of second filter patterns respectively overlapping the second sensing pixels. The first filter patterns allow the first light beam to pass and block the second light beam. The second filter patterns allow the second light beam to pass and block the first light beam.
Implementation Method 2
The sensing device is configured to receive the first light beam and the second light beam reflected from the sensing target
Data Source
AI summary
A time-of-flight sensing system including a first light source, a second light source, a sensing device and a filter layer is provided. The sensing device has a plurality of first sensing pixels and a plurality of second sensing pixels. The filter layer is disposed on a side of a light-receiving surface of the sensing device. The filter layer has a plurality of first filter patterns overlapping the first sensing pixels and a plurality of second filter patterns overlapping the second sensing pixels. The first light source and the second light source respectively and sequentially emit the first light beam having a first wavelength and the second light beam having a second wavelength toward a sensing target. The first sensing pixels and the second sensing pixels simultaneously and respectively sense the first light beam and the second light beam reflected from the sensing target. A time-of-flight sensing method is also provided.