Light Sensor Device with Integrated Optical Light Guide Tunnel
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Solution Overview
Problem
Conventional light sensors with large viewing angles receive light from multiple directions, which is undesirable in applications requiring sensitivity to light from a specific direction, and adding a collimator increases the overall size of the structure.
Innovation Solution
A light sensor device with a substrate having a well-defined surface and an optical light guide forming a transparent tunnel within an opaque body, extending from the top surface down a sloped side wall to the light sensor, acting as a built-in collimator to receive light from a specific direction, allowing for directional sensitivity without increasing the structure's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a collimator is added in front of a photodiode to achieve directional sensitivity, then the viewing angle is reduced, but the overall size of the structure increases
Solution Approach 1:
The patent merges the collimator function with the photodiode structure by forming the light guide tunnel directly within the substrate using the same semiconductor fabrication processes. This integration eliminates the need for a separate collimator component, achieving directional sensitivity while maintaining a compact form factor.
Solution Approach 2:
The light guide tunnel is nested within the substrate volume, utilizing the substrate's three-dimensional space. The tunnel extends from the front surface through the substrate to the photodiode at the rear, effectively embedding the collimating structure within the existing device footprint rather than adding external components.
2Illumination intensity
If photodiodes are made on a planar silicon surface with a lens, then the amount of incoming light is maximized, but the viewing angle becomes relatively large
Solution Approach 1:
The patent transitions from a two-dimensional planar photodiode surface to a three-dimensional structure with a light guide tunnel. The tunnel has specific geometric dimensions (width, depth, angle) that provide directional selectivity while the photodiode at the tunnel's end maintains high light sensitivity, thus resolving the contradiction between maximizing light input and achieving directional precision.
Solution Approach 2:
The light guide tunnel creates a localized optical path with specific directional properties, while the photodiode surface maintains its high light sensitivity. The tunnel's geometry (slope angle, aperture size) is optimized locally to provide directional filtering, while the photodiode's large active area at the tunnel's end maximizes light detection capability.
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 light sensor device achieves directional sensitivity with a compact design, enabling effective monitoring of individual LED performance in multi-color LED modules without the need for color filters, reducing electronic complexity and improving system cost and performance.
Implementation Method 1
an optical light guide comprising a transparent tunnel within an opaque body, which tunnel extends from a top surface of the device down a sloped side wall of the well to the location of the light sensor
Implementation Method 2
The substrate preferably comprises silicon and the light sensor comprises a photodiode
Data Source
AI summary
A light sensor device comprises a substrate (10) having a well (12) defined in one surface. At least one light sensor (14) is formed at the base of the well (12), and an optical light guide (18) in the form of a transparent tunnel (18) within an opaque body (20) extends from a top surface of the device down a sloped side wall of the well (12) to the location of the light sensor (14).