GMR Optical Filter Reflector Downsizing Image Sensors
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Solution Overview
Problem
Guided mode resonance (GMR) filters used in image sensors, such as CMOS and CCD image sensors, tend to increase the size of the image sensor due to the requirement for a large number of grating lines, leading to issues like upsizing and deterioration of wavelength characteristics.
Innovation Solution
Incorporating a reflector with a different refractive index than the core layer in the GMR filter structure, which allows for diffraction and interference of electromagnetic waves, reducing the need for a large number of grating lines and minimizing optical crosstalk between adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a GMR filter is used as a wavelength selection filter in an image sensor, then wavelength selection capability is improved, but the image sensor size increases
Solution Approach 1:
The patent changes the physical parameters of the optical filter by introducing a reflector with a different refractive index than the core layer. This parameter change enables the filter to achieve the same wavelength selection capability with a smaller physical size, directly resolving the contradiction between wavelength selection capability and sensor size.
Solution Approach 2:
The patent uses a composite structure combining a core layer and a reflector layer with different refractive indices. This composite material approach creates a more efficient optical filter that maintains wavelength selection performance while reducing the overall filter size, thereby downsizing the image sensor.
2Measurement precision
If a large number of grating lines are used in the GMR filter, then wavelength selection precision is improved, but device complexity increases
Solution Approach 1:
By changing the refractive index parameter through the addition of a reflector layer, the patent achieves wavelength selection precision without requiring a large number of grating lines. This parameter change simplifies the filter structure while maintaining or improving wavelength selection precision.
3Area of stationary object
If adjacent structural color filters are positioned close together, then device area is reduced, but optical crosstalk increases
Solution Approach 1:
The patent extracts and isolates the optical paths of adjacent structural color filters using reflectors. By positioning reflectors between adjacent filters, the optical crosstalk is prevented from spreading between neighboring pixels, allowing filters to be positioned closer together without increasing crosstalk.
Solution Approach 2:
The reflector acts as an intermediary element between adjacent structural color filters. This intermediary structure blocks and redirects stray light, preventing optical crosstalk while allowing the filters to be positioned in close proximity, thereby reducing the overall device area.
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 approach enables the downsizing of image sensors while maintaining excellent wavelength characteristics and reducing optical crosstalk, thereby improving the image sensor's performance and size efficiency.
Implementation Method 1
the optical filter includes a diffraction grating, a core layer, and a reflector disposed on first and second opposing sides of the core layer
Implementation Method 2
a reflector that reflects electromagnetic waves between adjacent structural color filters
Implementation Method 3
a structural color filter that uses interference of electromagnetic waves on an incidence plane of light or a plane parallel to the incidence plane
Data Source
AI summary
An imaging device includes a photodetector and an optical filter disposed on a light-receiving surface of the photodetector. The optical filter may include a diffraction grating, a core layer, and a reflector disposed on first and second opposing sides of the core layer. In some cases, the optical filter (e.g., a GMR filter) uses interference of electromagnetic waves on an incidence plane of light or a plane parallel to the incidence plane. The reflector may reflect electromagnetic waves between adjacent optical filters. The present technology can be applied to, for example, an image sensor provided with a GMR filter, such as a back-side-illuminated or front-side-illuminated CMOS image sensor.