Optical Sensor Module Uniform Illumination
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Solution Overview
Problem
Conventional optical sensor modules face issues with non-uniform illumination and low fill factor, leading to suboptimal image quality in applications like fingerprint detection, due to the use of backlight or side-emitting light sources which interfere with photodiode arrays.
Innovation Solution
The optical sensor module employs a self-illuminating material like OLED as a light source element, integrated with a light sensor and circuit unit on a substrate, where the light source is isolated from the sensor by an isolation element, allowing for uniform illumination and increased fill factor and aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a backlight element is disposed at the bottom of the optical sensor module, then the light source is provided, but the module height increases and light interference occurs requiring additional isolation elements
Solution Approach 1:
The patent transitions from a vertical stacking arrangement (backlight at bottom, sensor above) to a planar integration where the OLED light source is disposed in the same plane as the photodiode array. This dimensional change eliminates the need for vertical isolation structures and reduces module height while maintaining effective light source-sensor separation through planar isolation elements.
2Object-affected harmful factors
If a light blocking or isolation element is disposed between the backlight element and the photodiode array, then light interference is prevented, but the image quality deteriorates due to low efficiency
Solution Approach 1:
The patent introduces a transparent isolation element that acts as an intermediary between the OLED light source and the photodiode array. This element selectively blocks oblique light paths while transmitting useful light, achieving both interference prevention and high imaging efficiency through its selective optical mediation rather than complete light blocking.
3Length of stationary object
If a side-emitting light source is disposed laterally, then the module height is reduced, but the illuminating light uniformity deteriorates
Solution Approach 1:
The patent applies local quality by positioning the OLED light source at specific locations within the pixel unit structure rather than uniform lateral distribution. The light source is strategically disposed between isolation elements to create localized illumination zones that collectively achieve uniform overall illumination while maintaining low profile height.
4Measurement precision
If the photodiode array directly detects light from the backlight element, then the detection function is provided, but interference occurs resulting in poor image quality
Solution Approach 1:
The patent segments the optical path by introducing isolation elements that divide the space between light source and sensor into distinct regions. These isolation structures create separate optical channels that prevent direct light interference while allowing reflected light from the target object to reach the photodiode array for accurate 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
This configuration results in improved image uniformity and a lower profile for the sensor module, enhancing the fill factor and aperture ratio of each pixel unit, while allowing the self-illuminating material to perform both sensing and display functions.
Implementation Method 1
the photodiode array 202 detects the light L2 reflected from the upper surface (i.e., the touched surface) of the cover lens 203, when an object (e.g., finger) touches the cover lens, by frustrated total internal reflection (FTIR)
Implementation Method 2
The optical sensor module employs a self-illuminating material like OLED as a light source element
Data Source
AI summary
An optical sensor including a substrate and a plurality of pixel units are provided. The pixel units are disposed on the substrate, and each of the pixel units includes a light source element, a light sensor element, a circuit unit, and an isolation element. Herein, the light source element emits light, the light sensor element senses an optical image. The circuit unit is configured to drive the light source element to emit light and to drive the light sensor element to sense the optical image. The isolation element isolates the light sensor element from the light source element. In addition, the light source element is disposed between the isolation element of the respective pixel unit and an isolation element of a neighboring pixel unit.