Optical Ranging Systems with Cross-Talk Reducing Features
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Solution Overview
Problem
Optical cross-talk between the light emitter and pixels in optical ranging systems degrades the precision and sensitivity of distance measurements, particularly in small sensor designs, due to electrical interference and signal-to-noise ratio issues.
Innovation Solution
The optical ranging system incorporates features such as trenches in the TOF sensor chip, light reflective or absorptive materials on the adhesive or chip edges, light barriers on the support, and a light guide to direct light to reference pixels, all designed to reduce optical cross-talk by blocking or attenuating light emitted by the emitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sensor size is reduced to create small optical sensors, then the device compactness is improved, but optical cross-talk between components increases
Solution Approach 1:
The patent divides the sensor chip into distinct regions by introducing trenches that physically segment the pixel array from the light emitter area. This segmentation creates isolated zones that prevent optical cross-talk while maintaining compact overall sensor dimensions.
Solution Approach 2:
The patent introduces intermediary structures including light-absorbing materials positioned in the trenches and light barriers on the support substrate. These intermediary elements act as mediators that block stray light paths between the emitter and pixels, resolving the cross-talk issue without requiring larger sensor area.
2Measurement precision
If light barriers and trenches are added to reduce optical cross-talk, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into integrated structures. The trenches serve both as physical separators and as holders for light-absorbing materials. The light barriers on the support substrate simultaneously block stray light and provide structural organization. This merging reduces the number of separate components needed.
Solution Approach 2:
The patent applies light-absorbing materials selectively in specific locations (within trenches at pixel edges) rather than uniformly across the entire sensor. This localized application of quality enhancement achieves cross-talk reduction with minimal additional material and structural complexity.
3Object-affected harmful factors
If light-absorbing materials are applied on chip edges and adhesive surfaces, then optical cross-talk is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent designs the trench structure to be self-contained, where the light-absorbing material is positioned within the trench cavity formed during chip fabrication. This self-service approach allows the structure to guide and block light through its own geometry rather than requiring separate assembly steps for cross-talk mitigation components.
Solution Approach 2:
The patent incorporates light-absorbing materials during the chip fabrication process itself, before final assembly. The trenches are etched and filled with absorbing materials as part of the semiconductor manufacturing sequence, preparing the cross-talk reduction features in advance rather than adding them as post-processing steps.
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
These features effectively minimize optical cross-talk, enhancing the precision and sensitivity of distance measurements by preventing stray light from reaching the sensor pixels, thereby improving the accuracy and reliability of the optical ranging system.
Implementation Method 1
A barrier that is substantially non-transparent to light emitted by the light emitter separates the at least one reference pixel from the at least one main pixel
Implementation Method 2
the means for reducing optical cross-talk includes a light reflective or light absorptive material on an edge of the adhesive
Implementation Method 3
the means for reducing optical cross-talk includes a light reflective or light absorptive material on an edge of the adhesive
Implementation Method 4
The light barrier is operable to absorb or attenuate light having a wavelength of light emitted by the light emitter
Implementation Method 5
The light barrier is operable to absorb or attenuate light having a wavelength of light emitted by the light emitter
Implementation Method 6
a light guide to direct light to reference pixels
Data Source
AI summary
An optical ranging system includes a support, a light emitter mounted on the support, and a time-of-flight (“TOF”) sensor chip mounted on the support. The TOF sensor chip, for example, includes at least one main pixel and at least one reference pixel in a semiconductor substrate. A barrier that is substantially non-transparent to light emitted by the light emitter separates the at least one reference pixel from the at least one main pixel. The optical ranging system also includes features for reducing optical cross-talk between the light emitter and the pixels of the TOF sensor.