Shaped Color Filter Redirects Radiation to Photodiodes
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Solution Overview
Problem
Current image sensors in image capturing apparatuses require improved efficiency in capturing images, particularly due to limitations in color filter design that lead to reduced radiation reception and increased device size.
Innovation Solution
A photoactive device with a substrate, photodiodes, and a color filter array where each color filter has a shaped radiation receiving surface to redirect radiation directly to photodiodes, eliminating the need for a microlens array and enhancing radiation reception while reducing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional color filter with flat radiation receiving surface is used, then the device structure is simple, but radiation reception efficiency is reduced and device size increases
Solution Approach 1:
The color filter employs a curved radiation receiving surface instead of a flat surface. This curvature is designed to redirect incoming radiation at specific angles to match the angular acceptance profile of the photodiode, thereby improving radiation reception efficiency while maintaining a compact device form factor.
Solution Approach 2:
The invention modifies the geometric parameters of the color filter by introducing a curved surface with specific radius of curvature. This parameter change enables the filter to optimize the path of incoming radiation, directing it more effectively toward the photodiode active area, thus improving efficiency without increasing overall device volume.
2Productivity
If a microlens array is added to redirect radiation, then radiation reception efficiency improves, but device complexity and size increase
Solution Approach 1:
The invention merges the functions of the color filter and the radiation redirecting element into a single integrated component. The color filter itself is given a curved radiation receiving surface that performs both wavelength filtering and radiation redirection, eliminating the need for a separate microlens array and thereby reducing device complexity.
Solution Approach 2:
The color filter is designed to serve multiple functions simultaneously: it acts as a wavelength-selective filter and as a radiation redirecting element. The curved surface enables the filter to direct radiation toward the photodiode while maintaining its primary function of selecting specific wavelengths, thus achieving multi-functionality without adding device complexity.
3Productivity
If a curved radiation receiving surface is used in color filter, then radiation redirection to photodiode improves, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies particular ranges for the curvature parameters of the radiation receiving surface, such as the radius of curvature. By defining these parameters within specific ranges, the patent balances the need for effective radiation redirection with the practical constraints of manufacturing precision, ensuring that the curved surface can be produced with standard fabrication techniques.
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
The solution enables improved image capture efficiency by directing more radiation to photodiodes, reducing stray light, and minimizing device size without the need for a microlens array, thus enhancing the performance of image sensors in devices like cameras.
Implementation Method 1
Each color filter has a radiation receiving surface that is shaped to re-direct radiation to a respective photodiode
Data Source
AI summary
Embodiments described herein generally relate to an apparatus for capturing an image and a photoactive device for that apparatus. In one embodiment, the apparatus for capturing an image includes a lens and a photoactive device. The photoactive device is positioned behind the lens. The photoactive device includes a substrate, one or more photodiodes, and a color filter array. The one or more photodiodes are formed in the substrate. The color filter array is positioned over the substrate. The color filter array has one or more color filters. Each color filter has a radiation receiving surface that is shaped to re-direct radiation to a respective photodiode.