Reflective Color Filters for Image Sensor Light Utilization
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Solution Overview
Problem
Current color image sensors suffer from low light utilization efficiency due to absorptive color filters, which absorb most incident light, resulting in significant light loss and reduced image clarity.
Innovation Solution
The implementation of a reflective color filter array with a mirror layer, transparent light path changing elements, and micro lenses, where each color filter transmits specific wavelength bands and reflects others, optimized by spacer layers and light-absorbing or reflecting barriers, to enhance light utilization and image clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If absorptive color filters are used to separate colors, then color separation is achieved, but light utilization efficiency deteriorates significantly
Solution Approach 1:
The patent inverts the conventional absorptive color filter approach by using reflective color filters that reflect unwanted wavelengths instead of absorbing them. The reflective color filters transmit only specific wavelength bands (e.g., red, green, blue) and reflect other wavelengths, thereby achieving color separation while minimizing light loss and improving light utilization efficiency
Solution Approach 2:
The patent converts the reflected light, which would otherwise be wasted in absorptive filters, into a useful resource by directing it through mirrors and light path changing elements to reach the corresponding photo detectors. This transforms what was previously harmful light loss into beneficial light utilization
2Loss of energy
If reflective color filters are used to improve light utilization efficiency, then light loss is reduced, but device complexity increases
Solution Approach 1:
The patent segments the optical path into distinct functional components: reflective color filters for wavelength separation, mirrors for light redirection, light path changing elements for angle adjustment, and micro lenses for light concentration. Each component performs a specific function, allowing the complex system to be managed through modular segmentation
Solution Approach 2:
The patent adds spatial dimensions to the optical path by introducing mirrors and light path changing elements that operate in three-dimensional space. The light path is redirected at different angles and levels, utilizing vertical and lateral dimensions to route reflected light to appropriate photo detectors without interfering with adjacent pixels
3Loss of energy
If light path changing elements are introduced to redirect reflected light, then light utilization efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates preliminary alignment features during the manufacturing process, such as pre-defined spacer layer thicknesses and pre-positioned light path changing elements, to ensure proper optical alignment before final assembly. This preliminary action reduces the need for complex post-assembly adjustments
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 improves light utilization efficiency and maintains high color purity by reflecting unwanted wavelengths, reducing light loss and enhancing image quality.
Implementation Method 1
a color separation element may separate colors of an incident light by using a diffraction characteristic or a refraction characteristic that differs based on wavelengths
Implementation Method 2
the plurality of color filters are configured to transmit lights of corresponding wavelength bands only and reflect lights of other wavelength bands
Implementation Method 3
a plurality of micro lenses configured to concentrate an incident light onto the plurality of light path changing elements, respectively
Implementation Method 4
the plurality of transparent light path changing elements configured to tilt a light traveling direction
Data Source
AI summary
At least one example embodiment discloses an image sensor with an improved light utilization efficiency based on reflective color filters. Since the image sensors may use most of an incident light for forming an image by using reflective color filters, light loss due to light absorption may be reduced. Therefore, light utilization efficiency of the image sensors may be improved while embodying color purity.