Offset Pixel Image Sensor Layout for Petal Flare Blocking
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Solution Overview
Problem
Camera image sensors suffer from petal flare artifacts due to the periodicity of their pixel and microlens arrays, which cause diffracted light to be reflected back and create image distortions.
Innovation Solution
A flare-blocking image sensor design featuring large and small pixels with specific pitch offsets, a large microlens, and an opaque element strategically positioned between the large pixel and microlens to absorb diffracted light, reducing petal flare while minimizing obstruction of direct image illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a periodic pixel array and microlens array are used in the image sensor, then the image sensor can effectively capture light and form images, but the periodicity causes diffraction of incident light toward the imaging lens, which is reflected back to produce petal flare artifacts
Solution Approach 1:
An intermediate layer is introduced between the microlens array and the pixel array to absorb diffracted light before it reaches the pixel array. This intermediary layer prevents the harmful diffraction effect while allowing direct light to pass through to the pixels, thereby eliminating petal flare without compromising image quality
Solution Approach 2:
The periodic structure that causes diffraction is converted into a beneficial anti-reflective coating pattern. By designing the intermediate layer with specific periodic features matching the pixel pitch, the diffracted light is redirected into harmless orders or absorbed, transforming the harmful diffraction effect into a useful anti-flare mechanism
2Object-generated harmful factors
If an opaque element is added to block diffracted light, then petal flare is reduced, but the device complexity increases
Solution Approach 1:
The anti-reflective coating and the intermediate layer are merged into a single integrated structure. The intermediate layer serves dual functions: it acts as both the structural support and the light-absorbing medium, eliminating the need for separate opaque elements and reducing overall device complexity
Solution Approach 2:
The intermediate layer is designed to perform multiple functions simultaneously: it provides mechanical support, absorbs diffracted light, and maintains the periodic structure needed for light guidance. This multi-functionality reduces the number of separate components needed, thereby simplifying the overall device structure
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
Effectively blocks diffracted light that causes petal flare while allowing direct image light to pass through, thereby reducing image artifacts and improving image quality.
Implementation Method 1
The first opaque element extends, in the first direction, a distance d1 less than λ/(2n) from a boundary between the first small pixel and the first large pixel and toward the second small pixel
Implementation Method 2
The periodicity of the image sensor's pixel array and microlens array thereon result in the image sensor resembling a reflective two-dimensional diffraction grating. Part of light incident on the image sensor is diffracted toward the camera's imaging lens.
Data Source
AI summary
A flare-blocking image sensor includes large pixels and small pixels, a microlens, and an opaque element. The large pixels and small pixels form a first and second pixel array respectively, each having a pixel pitch Px and Py. The second pixel array is offset from the first pixel array by ½Px and ½Py. A first large pixel of the large pixels is between and collinear with a first and a second small pixel separated by √{square root over (Px2+Py2)} in a first direction and each having a width W less than both pixel pitch Px and Py. The microlens is aligned with the first large pixel. The opaque element is between the first large pixel and the microlens and extends, in the first direction, less than12(Px2+Py2-W)from the first small pixel toward the second small pixel. The opaque element has a width perpendicular to the first direction not exceeding width W.