On-Chip Lens Array for Flare Reduction in Imaging Devices
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Solution Overview
Problem
Imaging devices face challenges in reducing flare caused by diffraction phenomena due to the reflection of light on regularly disposed on-chip lenses, which leads to light being incident at various angles and entering pixels intended for other light paths.
Innovation Solution
The implementation of on-chip lenses with a pitch less than the longest wavelength side of the light region to be received, combined with a transparent substrate on the light incident side, suppresses the diffraction phenomenon and subsequent flare by ensuring that light is focused within the intended pixel area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If on-chip lenses are densely provided in a single plane to enhance photoelectric conversion efficiency, then light condensation is improved, but flare increases due to diffraction phenomena
Solution Approach 1:
The patent divides the single-plane on-chip lens array into multiple layers. Specifically, it employs a first on-chip lens layer and a second on-chip lens layer positioned at different depths (first depth and second depth, respectively). This segmentation allows each layer to focus light at different focal planes, reducing the diffraction-induced flare that occurs in single-plane configurations while maintaining enhanced photoelectric conversion efficiency through multi-layer light condensation.
Solution Approach 2:
The patent transitions from a two-dimensional single-plane lens arrangement to a three-dimensional multi-layer configuration. By positioning on-chip lenses at different depths (first depth and second depth), the system utilizes the vertical dimension to separate light paths and focal planes. This dimensional change effectively reduces flare by preventing light from diffracting into adjacent pixels while still concentrating light onto the photoelectric conversion elements.
2Object-generated harmful factors
If on-chip lenses are provided at a pitch less than the longest wavelength to suppress diffraction, then flare is reduced, but device complexity increases
Solution Approach 1:
The patent segments the on-chip lens structure into multiple layers with different pitch configurations. The first on-chip lens layer and second on-chip lens layer can have different pitch values, allowing optimization for different wavelength ranges. This segmentation enables flare suppression for specific wavelengths without requiring the entire array to use an excessively small pitch, thereby reducing overall device complexity.
Solution Approach 2:
The patent applies different pitch characteristics to different layers of on-chip lenses. The first on-chip lens layer may have a first pitch optimized for certain wavelengths, while the second on-chip lens layer has a second pitch optimized for other wavelengths. This local optimization allows flare suppression for the target wavelength range without uniformly increasing complexity across the entire lens array.
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 effectively reduces flare by minimizing diffraction effects, enhancing the imaging device's performance and allowing for miniaturization without increasing the risk of flare generation.
Implementation Method 1
The on-chip lens enhances a photoelectric conversion efficiency in a light reception section by condensing light that enters the light reception section
Implementation Method 2
The flare is generated by: occurrence of a diffraction phenomenon at a time when incident light entering a pixel is reflected on regularly disposed on-chip lenses
Data Source
AI summary
Provided is an imaging device including a light reception section that includes a plurality of pixels each performing photoelectric conversion and a plurality of on-chip lenses that is provided on a light incident side of the light reception section at a pitch less than a length of a wavelength on a longest wavelength side of a wavelength region of light to be received by the light reception section. The imaging device further includes a transparent substrate that is provided on a light incident side of the on-chip lenses.