Optical Sensor Layout Using Backlight and Light-Blocking Layers
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Solution Overview
Problem
Optical sensors face challenges in achieving high detection accuracy while being compact in size, particularly due to complex module structures when the light source is disposed above the detection area or uneven light distribution when lateral, necessitating a design that enhances detection precision while minimizing size.
Innovation Solution
A detection device with a substrate having photodiodes, light-blocking layers, and a backlight configuration that directs reflected light from the object to the photodiodes while blocking direct light emission, utilizing a light guide portion and light-blocking layers to improve detection accuracy and reduce device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light source is disposed above the object to be detected, then the detection accuracy may be improved, but the module structure becomes complicated and difficult to be downsized
Solution Approach 1:
The patent transitions from a lateral light source arrangement to a vertical arrangement where the light source is positioned on the rear surface of the substrate, directly illuminating the object from below. This dimensional change simplifies the module structure by eliminating the need for complex lateral light guiding components while maintaining effective illumination for detection.
Solution Approach 2:
The patent extracts and removes the light guide portion from the module structure. By directly positioning the light source on the rear surface, the complex light guide components that were previously needed to direct light laterally are eliminated, simplifying the overall module structure while maintaining detection functionality.
2Area of stationary object
If the light source is disposed on a lateral side of the object to be detected, then the in-plane distribution of the amount of light detected by the optical sensor may be enlarged, but the device size increases
Solution Approach 1:
The patent changes the light source arrangement from lateral to vertical (from the side to the rear surface), allowing light to illuminate the object from below. This enables a larger effective detection area without increasing the lateral footprint of the device, as the light propagation occurs primarily in the vertical dimension rather than expanding the horizontal device dimensions.
3Volume of moving object
If the light source is disposed close to the photodiodes, then the device size is reduced, but direct light emission interferes with detection accuracy
Solution Approach 1:
The patent segments the device into distinct functional layers: the light source layer on the rear surface, the object placement region in the middle, and the photodiode array layer on the front surface. This spatial segmentation allows the light source to be positioned close to the photodiodes in terms of vertical proximity while maintaining functional separation that prevents direct light interference, as the object itself acts as an intermediate layer.
Solution Approach 2:
The object being detected serves as an intermediary between the light source and the photodiodes. The light source illuminates the object from the rear, and the photodiodes detect light reflected or transmitted through the object. This intermediary arrangement allows close positioning of light source and detector while maintaining detection accuracy, as the object mediates the light interaction and prevents direct illumination of the photodiodes.
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 proposed design enhances detection accuracy for fingerprint and vascular patterns by primarily utilizing reflected light, reducing interference from direct light emission, and allows for a more compact sensor form factor.
Implementation Method 1
a plurality of photodiodes provided corresponding to the first electrodes, and each including a first carrier transport layer, an active layer, and a second carrier transport layer
Implementation Method 2
a plurality of light-blocking layers provided between the backlight and the photodiodes
Implementation Method 3
directly embodying a detection device capable of obtaining excellent detection accuracy
Data Source
AI summary
According to an aspect, a detection device includes: a substrate; a plurality of first electrodes arranged on a first principal surface of the substrate; a plurality of photodiodes provided corresponding to the first electrodes, and each including a first carrier transport layer, an active layer, and a second carrier transport layer; a second electrode provided across the photodiodes; a backlight provided on a second principal surface side opposite to the first principal surface of the substrate; a plurality of light-blocking layers provided between the backlight and the photodiodes; and a light-transmitting area formed between adjacent light-blocking layers of the light-blocking layers.