SPAD Reference Pixel Layout With Light Guiding and Shielding
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Solution Overview
Problem
Existing distance measurement sensors using the Time-of-Flight method with SPAD pixels face uncertainty due to background light being used for reference pixels.
Innovation Solution
A light receiving device and distance measurement system that include pixels with a light shielding member and a light guiding unit, ensuring that light is surely received by reference pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If background light is used for reference pixels in distance measurement sensors, then the reference pixels can perform distance measurement, but the measurement precision deteriorates due to uncertainty in background light reception
Solution Approach 1:
The patent introduces a light guiding unit as an intermediary component between the light emission source and the reference pixel's light receiving element. This light guiding unit actively guides and directs light from the emission source to the reference pixel, replacing the passive reliance on background light. By using this intermediary structure, the system ensures consistent and controllable light reception for reference pixels, thereby improving measurement precision while maintaining distance measurement capability
Solution Approach 2:
The patent implements a structure where the light emission source serves dual purposes: it provides illumination for measurement pixels and simultaneously serves as the light source for reference pixels through the light guiding unit. This self-service approach eliminates the need for separate light sources for reference pixels, reducing system complexity while ensuring reliable light reception for accurate reference measurements
2Reliability
If a light shielding member is provided between the light receiving element and the light emission source, then light reception reliability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the light shielding function with the light guiding structure by integrating the light shielding member into the same component that provides structural support and light guidance. This combination approach achieves reliable light reception control (blocking unwanted direct light while allowing guided light) without adding separate shielding components, thereby limiting the increase in device complexity while improving light reception 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
The solution effectively addresses the uncertainty in background light usage, enabling accurate distance measurement by ensuring reliable light reception for reference pixels.
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
In the SPAD, 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
Data Source
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.