Microlens Array Shape Optimization for Color Sensitivity
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Solution Overview
Problem
Existing solid-state image pickup devices with RGB color pixels do not optimize sensitivity characteristics for each color, as microlenses are typically formed with the same shape for red and blue pixels, not considering wavelength dispersion of optical refractive index.
Innovation Solution
A solid-state image pickup device with a microlens array where each microlens has a unique shape corresponding to the color of the pixel, with red, green, and blue microlenses having different curvature radii optimized for their respective wavelengths, and ends of adjacent microlenses either in contact or overlapping, to enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If microlenses are formed with the same shape for red and blue pixels, then manufacturing is simplified, but sensitivity characteristics for each color are not optimized
Solution Approach 1:
The patent applies local quality by forming microlenses with different shapes (different curvature radii) for different color pixels (red, green, blue) based on their specific wavelength requirements. Each microlens shape is locally optimized for its corresponding color's sensitivity characteristics, rather than using a uniform shape for all pixels.
Solution Approach 2:
The patent changes the curvature radius parameter of microlenses according to the wavelength of each color. By adjusting this geometric parameter, the patent optimizes light collection efficiency for each color channel, transforming a single-parameter design into a multi-parameter optimized system.
2Reliability
If microlenses are formed with gaps between adjacent pixels, then thermal fusion during manufacturing is avoided, but light collection efficiency is reduced
Solution Approach 1:
The patent changes the curvature radius parameter of microlenses to enable adjacent microlenses to contact or overlap without causing pattern breakdown during thermal reflow. By optimizing the curvature radius, the patent achieves both high light collection efficiency (no gaps) and manufacturing reliability (no thermal fusion).
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 optimizes sensitivity characteristics for each color, improving image quality by enhancing light collection and transmission, allowing for higher sensitivity and better image capture.
Implementation Method 1
a microlens array section including a plurality of microlenses each configured to collect the light for corresponding one of the pixels
Implementation Method 2
a filter section including filters that are disposed corresponding to respective pixels, and each allowing light of a color that corresponds to corresponding one of the pixels to transmit therethrough
Data Source
AI summary
A solid-state image pickup device includes: a filter section including filters that are disposed corresponding to respective pixels, and each allowing light of a color that corresponds to corresponding one of the pixels to transmit therethrough, in which the pixels are each configured to receive the light of the predetermined color; and a microlens array section including a plurality of microlenses each configured to collect the light for corresponding one of the pixels, in which the microlenses are stacked with respect to the filter section, and are arranged in an array pattern corresponding to the respective pixels. The microlenses have two or more shapes that are different from one another corresponding to the respective colors of the light to be received by the pixels, and each having an end that is in contact with the end of adjacent one of the microlenses.