PCB Reflective Optical Detector for Infrared Light Loss Reduction
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Solution Overview
Problem
Existing optical detectors for infrared radiation suffer from significant light loss due to their partially transparent photoconductive layers, and the addition of reflective gold coatings complicates the manufacturing process, necessitating a simpler and cost-efficient solution that minimizes light loss while maintaining reliability.
Innovation Solution
The optical detector incorporates a reflective layer on a printed circuit board with a rough surface to redirect incident light back into the sensor layer, combined with a photosensitive material layer and an adhesive layer to enhance light absorption, and an evaluation device to process the sensor signal effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective gold coating is placed on the backside of the glass substrate to reduce light loss, then light absorption is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces the expensive and complex gold reflective coating with a simple white paint layer applied directly on the PCB. This disposable-like approach uses inexpensive materials (white paint instead of gold) and simple application methods (painting instead of vacuum deposition) to achieve the same light reflection function, dramatically reducing manufacturing complexity and cost while maintaining effectiveness in reducing light loss
Solution Approach 2:
The patent introduces an adhesive layer as an intermediary between the PCB and the sensor layer. This adhesive layer with its rough surface structure serves as a light-trapping intermediary that scatters and redirects light multiple times through the sensor layer, enhancing absorption without requiring a separate reflective coating. The adhesive layer mediates between the structural PCB and the functional sensor layer, providing both mechanical bonding and optical enhancement
2Measurement precision
If the photoconductive layer is made thin to improve detection sensitivity, then detection precision is improved, but light absorption decreases
Solution Approach 1:
The patent addresses the thin-layer absorption problem by adding a vertical dimension of light path extension through the reflective white paint layer on the PCB. Light that passes through the thin sensor layer is reflected back upward, creating a second pass through the sensor material. This dimensional approach to light path management allows thin sensor layers to achieve effective absorption comparable to much thicker layers, maintaining detection sensitivity while reducing light loss
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
This configuration significantly reduces light loss and simplifies the manufacturing process, providing a reliable and cost-efficient means for detecting infrared radiation by effectively redirecting and absorbing incident light, while maintaining high reflectivity and sensitivity.
Implementation Method 1
a reflective layer, in particular on a printed circuit board, is provided, wherein the reflective layer is designed to redirect incident light into the sensor layer
Implementation Method 2
a sensor layer comprising at least one photosensitive material, in particular a photoconductive material
Data Source
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AI summary
The invention relates to a detector (110) for optical detection comprising a circuit carrier (130) designed to carry at least one layer, wherein the circuit carrier (130) is or comprises a printed circuit board (132); a reflective layer (138), the reflective layer (138) being placed on a partition of the circuit carrier (130), wherein the reflective layer (138) is designed to reflect the incident light beam (120), thereby generating at least one reflected light beam (124); a substrate layer (114), the substrate layer (114) being directly or indirectly adjacent to the reflective layer (138), wherein the substrate layer (1 14) is at least partially transparent with respect to the incident light beam (120); a sensor layer (122), the sensor layer (122) being placed on the substrate layer (114), wherein the sensor layer (122) is designed to generate at least one sensor signal in a manner dependent on an illumination of the sensor layer (122) by the incident light beam and the reflected light beam (124); and an evaluation device (140) designed to generate at least one item of information by evaluating the sensor signal; and at least two individual electrical contacts (148, 148') contacting the sensor layer (122), wherein the electrical contacts (148, 148') are designed to transmit the sensor signal via the circuit carrier (130) to the evaluation device (150). The detector (110) constitutes a detector for detecting optical radiation, especially within the infrared spectral range, specifically with regard to sensing at least one of transmissivity, absorption, emission and reflectivity, being capable of avoiding a loss of incident light.