Reflected-Light Photodiode Detection with 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 object or uneven light distribution when lateral, necessitating a more efficient design.
Innovation Solution
A detection device with a substrate, photodiodes, light-blocking layers, and a backlight configuration that directs light reflected from the object to the photodiodes while blocking direct light emission, using a light guide portion and light-blocking layers to enhance detection accuracy and reduce 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 is improved, but the module structure becomes complicated and difficult to be downsized
Solution Approach 1:
The patent combines the light source and optical sensor into a single integrated module where the light source is disposed in the same plane as the optical sensor. This merging eliminates the need for separate light source housings and complex optical paths, thereby reducing module structure complexity while maintaining compact dimensions for portable devices
Solution Approach 2:
The patent transitions from a vertical stacking arrangement (light source above sensor) to a planar lateral arrangement (light source beside sensor in the same plane). This dimensional change enables a more compact footprint suitable for portable devices while simplifying the module structure by eliminating the need for complex vertical integration
2Volume of moving object
If the light source is disposed on a lateral side of the object to be detected, then the device size is reduced, but the in-plane distribution of the amount of light detected by the optical sensor is enlarged
Solution Approach 1:
The patent employs a microlens array positioned between the light source and optical sensor to create localized light concentration zones. Each microlens focuses light onto corresponding regions of the optical sensor, ensuring uniform light distribution across the detection plane while maintaining the compact lateral arrangement of the device
Solution Approach 2:
The patent introduces a microlens array as an intermediary optical element between the light source and optical sensor. This mediator corrects the non-uniform light distribution by focusing and redirecting light rays, ensuring even illumination across the sensor plane while preserving the compact device dimensions enabled by the lateral light source placement
3Measurement precision
If a backlight is provided to illuminate the object, then the detection accuracy is improved, but direct light from the backlight may reach the photodiodes causing interference
Solution Approach 1:
The patent extracts and removes direct light paths from the backlight to the photodiodes by positioning the light source laterally and using a light guide structure. This separation eliminates the harmful direct light interference while preserving the beneficial reflected light detection path, thereby improving signal quality and detection accuracy
Solution Approach 2:
The patent segments the optical path into distinct regions using light-blocking layers that separate the direct light path from the reflected light path. By dividing the optical space and selectively blocking direct backlight illumination of the photodiodes, the system eliminates interference while maintaining the illumination needed for reflected light detection
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 device achieves improved detection accuracy for fingerprint and vascular patterns by primarily utilizing reflected light, reducing the overall size and complexity, and allowing for flexible configurations such as using flexible OLED light sources.
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
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.