Spectroscopic Pixel Array for Higher-Sensitivity Image Capture
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Solution Overview
Problem
Conventional image capturing elements using color filters suffer from low light utilization efficiency, limiting the sensitivity of the image capturing element, especially as pixel density increases.
Innovation Solution
The image capturing element incorporates a pixel array with photoelectric conversion elements and a spectroscopic element array, where each spectroscopic element includes microstructures made of materials with a higher refractive index than the transparent layer, capable of separating incident light into different wavelength regions and directing them to corresponding pixels without the need for color reconstruction by signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If color filters are used for color separation, then color information can be acquired, but light utilization efficiency decreases due to absorption and reflection losses
Solution Approach 1:
The patent replaces the conventional color filter system (which relies on absorption and reflection) with a microlens system that directs different wavelength components of light to different photoelectric conversion elements through refraction and total internal reflection. This substitution eliminates the light loss inherent in color filters while maintaining color separation functionality.
Solution Approach 2:
The patent divides the incident light into different wavelength regions (red, green, blue) and directs each region to dedicated photoelectric conversion elements using microlenses. This segmentation approach allows each wavelength component to be captured efficiently without the absorption losses of color filters.
2Loss of energy
If spectroscopic elements such as prisms or dichroic mirrors are used, then light utilization efficiency improves, but integration difficulty increases due to the need to maintain function and characteristics
Solution Approach 1:
The patent changes the scale parameter of spectroscopic elements from macroscopic (prisms, dichroic mirrors) to microscopic (microlenses with diameters of several micrometers). This parameter change enables integration with photoelectric conversion elements while maintaining the light separation function, thus improving both manufacturability and light utilization efficiency.
Solution Approach 2:
The patent transitions from using planar spectroscopic elements (dichroic mirrors) or angular elements (prisms) to three-dimensional microlens structures that can be integrated in the vertical dimension above each pixel. This dimensional change allows for compact integration without compromising the spectroscopic separation function.
3Adaptability or versatility
If signal processing with matrix operations is used for color reconstruction, then color information can be obtained from micro beam structures, but signal-to-noise ratio deteriorates due to processing noise
Solution Approach 1:
The patent performs the color separation action preliminarily through optical means (microlenses directing different wavelengths to different pixels) before detection. This preliminary optical separation eliminates the need for subsequent signal processing to separate colors, thereby preserving the signal-to-noise ratio while maintaining color reconstruction capability.
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 enhances light utilization efficiency, reduces the burden of signal processing, and improves the sensitivity of the image capturing element while maintaining compatibility with existing manufacturing processes and image capturing systems.
Implementation Method 1
A microlens 103 is arranged on the color filter 104. When light is incident from the microlens 103
Implementation Method 2
the color filter 104 transmits only the light in the desired wavelength band and absorbs or reflects the light in the undesired wavelength band
Implementation Method 3
a photoelectric conversion element 102 is arranged on electrical wiring 112
Implementation Method 4
the phase delay effect felt by the incident light in and around the micro beam structures varies largely in one wavelength region and is almost equal in the other wavelength region
Data Source
AI summary
An image capturing element according to the present disclosure includes a pixel array formed by a plurality of pixels arranged in an array on a substrate, each of the plurality of pixels including a photoelectric conversion element, a transparent layer formed on the pixel array, and a spectroscopic element array formed by a plurality of spectroscopic elements arranged in an array, and each of the plurality of spectroscopic elements is at a position corresponding to one of the plurality of spectroscopic elements inside or on the transparent layer. Each of the plurality of spectroscopic elements includes a plurality of microstructures formed from a material having a refractive index higher than a refractive index of the transparent layer. The plurality of microstructures have a microstructure pattern. Each of the plurality of spectroscopic elements separates incident light into deflected light beams having different propagation directions according to the wavelength.