SPAD Light-Receiving Pixels with Shielding and Light Guidance
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Solution Overview
Problem
Existing distance measurement sensors using single photon avalanche diodes (SPADs) face uncertainty in background light detection by reference pixels.
Innovation Solution
A light receiving device and distance measurement system with a configuration that includes a first pixel with a light shielding member and a second pixel with a light guiding unit between the light receiving element and the light emission source, ensuring accurate light reception by the reference pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light shielding member is provided between the light receiving element and the light emission source, then measurement precision is improved by blocking unwanted light, but device complexity increases due to additional components
Solution Approach 1:
The patent merges the light shielding function with the pixel structure itself by making the light shielding member an integral part of the pixel configuration. The light shielding member is positioned between the light receiving element and light emission source within the same pixel, combining measurement and shielding functions in a unified structure rather than adding separate shielding components.
Solution Approach 2:
The patent introduces a light guiding unit that redirects light from the light emission source to the light receiving element through a different spatial path. By adding this dimensional routing element, the system enables precise light control without requiring complex multi-layer shielding structures, resolving the contradiction between measurement precision and device complexity.
2Reliability
If a light guiding unit is provided to propagate photons from the light emission source to the light receiving element, then light reception reliability is improved, but device complexity increases
Solution Approach 1:
The light guiding unit serves multiple functions simultaneously: it guides light from the emission source to the receiving element, defines the optical path, and works in conjunction with the light shielding member to block unwanted light. This multi-functionality reduces the need for separate components, improving reliability while limiting the increase in device complexity.
Solution Approach 2:
The light guiding unit acts as an intermediary element between the light emission source and light receiving element, mediating the light transmission process. This intermediary structure enables reliable light propagation through a controlled path without requiring direct line-of-sight alignment, thereby improving reliability while maintaining a manageable device structure.
3Measurement precision
If reference pixels are used to detect background light, then measurement precision is improved, but uncertainty remains in background light detection
Solution Approach 1:
The patent applies different structural qualities to different pixel types within the same array. Reference pixels are equipped with both light shielding members and light guiding units, creating a localized optimized structure specifically for background light detection. This local quality enhancement ensures that reference pixels can accurately detect background light without being affected by stray light from the emission source, improving both precision and reliability.
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
Ensures reliable light reception by the reference pixel, reducing uncertainty and improving the accuracy of distance measurements.
Implementation Method 1
a light guiding unit that is configured to propagate a photon and is provided between the light receiving element and the light emission source
Implementation Method 2
Some of such distance measurement sensors use a single photon avalanche diode (SPAD) as a pixel... if one photon enters a high-field PN junction region in a state in which a voltage larger than a breakdown voltage is applied, avalanche amplification occurs
Implementation Method 3
a first pixel including a light shielding member provided between the light receiving element and the light emission source
Data Source
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AI summary
The present technology relates to a light receiving device and a distance measurement system that enable light to be surely received by a reference pixel. A light receiving device includes a plurality of pixels each including a light receiving element having a light receiving surface, and a light emission source provided on an opposite side of the light receiving surface with respect to the light receiving element. The plurality of pixels includes a first pixel including a light shielding member provided between the light receiving element and the light emission source, and a second pixel including a light guiding unit that is configured to propagate a photon and is provided between the light receiving element and the light emission source. The present technology can be applied to a distance measurement system or the like that detects a distance to a subject in a depth direction, for example, for example.