Image Sensor Lens Offset to Avoid Photodiode Pad Obstruction
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Solution Overview
Problem
Conventional image sensors face challenges in aligning the focus of optical components with the centers of photodiodes, leading to suboptimal light convergence and potential interference from metal pads, which can block light intended for photodiodes.
Innovation Solution
The image sensor design incorporates a grid with apertures and optical components, including lenses that misalign their focus points with the photodiode centers, ensuring light convergence directly on the photodiodes while avoiding obstruction by metal pads, and optionally includes waveband filters within the apertures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the focus of the lens is aligned with the center of the photodiode, then the light convergence is optimized, but the metal pad may obstruct the light
Solution Approach 1:
The patent deliberately misaligns the lens focus point with the photodiode center, creating an asymmetric configuration where the focus point is positioned at a specific offset distance from the photodiode center. This asymmetric arrangement ensures that light converges on the photodiode active area while avoiding obstruction by the metal pad, which is typically positioned at the center of the photodiode. By accepting and designing this misalignment rather than correcting it, the patent resolves the contradiction between optimal light convergence and avoiding metal pad obstruction.
2Object-affected harmful factors
If the lens focus is misaligned with the photodiode center, then the metal pad obstruction is avoided, but the light convergence efficiency may be reduced
Solution Approach 1:
The patent optimizes the misalignment parameter by specifying a precise offset distance between the lens focus point and the photodiode center. This parameter change transforms the misalignment from a detrimental defect into an optimized design feature. By carefully controlling the offset distance, the patent achieves sufficient light capture efficiency while completely avoiding metal pad obstruction, thus resolving the contradiction between avoiding obstruction and maintaining capture efficiency.
3Illumination intensity
If multiple lenses are used to improve light convergence, then the focus coverage is enhanced, but the alignment complexity increases
Solution Approach 1:
The patent employs multiple lenses arranged in specific patterns (such as four lenses positioned at the corners of a rectangle or square) to divide the light collection task among several components. Each lens contributes to focusing light on the photodiode, and their combined effect provides enhanced focus coverage. This segmentation approach allows the system to achieve better light convergence while distributing the alignment complexity across multiple identical or similar lens units, making the overall system more manageable.
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 design enhances light convergence efficiency by ensuring that light is focused directly on photodiodes without being blocked by metal pads, improving the overall performance of the image sensor.
Implementation Method 1
The optical components includes a first optical component above a first photodiode of the plurality of photodiodes, the first optical component includes at least one lens and provides at least one focus on the first photodiode
Implementation Method 2
solid-state imaging devices, for example charge-coupled device (CCD) sensors or complementary metal-oxide semiconductor (CMOS) sensors, have photoelectric transducers such as photodiodes for converting light into electric charges
Data Source
AI summary
An image sensor includes a photodiode array having a plurality of photodiodes, a grid disposed over the photodiode array, and a plurality of optical components disposed over the grid and corresponding to the plurality of apertures, respectively. The grid defines a plurality of apertures corresponding to the plurality of photodiodes, respectively. The optical components includes a first optical component above a first photodiode of the plurality of photodiodes, the first optical component includes at least one lens and provides at least one focus on the first photodiode, in which the focus of the lens of the first optical component misaligns a center of the first photodiode, in a plan view.