Solid-State Image Sensor Light Dispersing Array for High Optical Efficiency
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Solution Overview
Problem
Conventional image sensors face challenges in achieving high optical efficiency and color reproducibility without significantly increasing the number of photosensitive cells, especially at higher cell pitches, due to the limitations of light-absorbing color filters and the need for multiple photosensitive cells when using dichroic mirrors or micro prisms.
Innovation Solution
A solid-state image sensor with a photosensitive cell array and a light dispersing element array that includes first and second types of light dispersing elements, which split incoming light to direct specific color components to corresponding photosensitive cells, allowing for high optical efficiency and color reproducibility without a substantial increase in the number of photosensitive cells, even at high cell pitches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a subtractive color filter using organic pigment is arranged to face each photosensitive cell, then color separation is achieved, but optical efficiency decreases because the filter absorbs unwanted color components
Solution Approach 1:
The patent replaces the mechanical/optical absorption system (subtractive color filters that absorb unwanted wavelengths) with a different physical approach using multiple photosensitive cells with different spectral sensitivities. Instead of filtering light before detection, the system detects all wavelengths simultaneously using cells tuned to different spectral ranges, eliminating the energy loss inherent in absorption-based filtering.
Solution Approach 2:
The patent segments the detection function across multiple types of photosensitive cells (first, second, third, and fourth photosensitive cells) with different spectral sensitivities. Rather than using a single filter per cell, each cell type detects specific wavelength ranges, and the combined output from all cell types provides full color information without the need for absorbing filters.
2Measurement precision
If the number of pixels in an image sensor is increased to improve resolution, then more pixels are integrated, but the intensity of light falling on a single pixel decreases and sensitivity drops
Solution Approach 1:
The patent makes each photosensitive cell multi-functional by designing cells with different spectral sensitivities that can detect multiple wavelength ranges. The first photosensitive cell detects blue and violet light, the second detects green and yellow-green, the third detects yellow and red, and the fourth detects red and near-infrared. This allows each cell to contribute to multiple color channels, effectively increasing the light-gathering capability while maintaining high resolution.
Solution Approach 2:
The patent changes the spectral sensitivity parameters of the photosensitive cells to overlap in a way that maximizes light utilization. By configuring the spectral response curves of different cell types to complement rather than duplicate each other, the system ensures that across the entire visible spectrum, light is efficiently captured without requiring larger pixel areas.
3Loss of energy
If dichroic mirrors are used to increase optical efficiency by transmitting only specific wavelength ranges, then light loss is reduced, but the number of photosensitive cells must be tripled to detect all color components
Solution Approach 1:
The patent merges the detection functions of multiple cell types within a single pixel structure. Instead of requiring separate pixels for each color component (which would triple the cell count), the invention combines four different photosensitive cell types with different spectral sensitivities into a single integrated pixel unit. This allows all color information to be captured simultaneously without increasing the overall pixel count or requiring complex dichroic mirror systems.
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 enables high-sensitivity image capture with high optical efficiency and color reproducibility, minimizing light loss and maintaining performance across various cell pitches, including those over 1 μm, by effectively splitting and directing light components to photosensitive cells.
Implementation Method 1
a light dispersing element array that is arranged so as to face the photosensitive cell array and that includes first and second types of light dispersing elements
Implementation Method 2
photosensitive cells that perform photoelectric conversion on incident light
Data Source
AI summary
This solid-state image sensor includes a photosensitive cell array including first through fourth photosensitive cells 2a to 2d and a light dispersing element array that is arranged to face the photosensitive cell array and that includes first and second types of light dispersing elements 1a, 1b. If light that would be directly incident on each photosensitive cell, were it not for the light dispersing element array, is called that photosensitive cell's entering light, the light dispersing element array is configured so that the first type of light dispersing element 1a makes a part of light rays with the first color component, which is included in the entering light of each of the first and second photosensitive cells 2a, 2b, incident on the first photosensitive cell 2a and that the second type of light dispersing element 1b makes a part of light rays with the second color component, which is included in the entering light of each of the third and fourth photosensitive cells 2c, 2d, incident on the fourth photosensitive cell 2d.