Wafer Level Image Module Focus Offset Compensation
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Solution Overview
Problem
Conventional wafer level image modules face issues with focus accuracy due to lens deformation during manufacturing and size tolerance errors, leading to out-of-focus problems and inaccurate image mapping.
Innovation Solution
A wafer level image module with an adjustment member, such as a glass ball or fiber spacer, is introduced between the photo sensor and the lens set to compensate for focus offset, allowing for in-situ adjustment and testing to ensure precise focusing and high image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If lenses are stacked and closely attached to the image pickup device through integrated circuit manufacturing process, then the size is minimized for use in consumer electronics, but the lenses deform by manufacturing process and temperature causing focus offset
Solution Approach 1:
A spacer is introduced as an intermediary component between the lens and the image pickup device. This spacer acts as a mediator that precisely controls the distance between the lens and photo sensor, compensating for focus offset caused by lens deformation during manufacturing. The spacer is positioned in the optical path and its thickness is carefully controlled to achieve accurate focusing.
Solution Approach 2:
The invention changes the physical parameter of the optical system by introducing a spacer with a specific thickness to adjust the distance between the lens and image pickup device. This parameter change compensates for the focus offset caused by manufacturing variations and thermal deformation, allowing the system to achieve accurate focusing despite the miniaturization constraints.
2Ease of manufacture
If glass chips with thickness tolerance of 0-20 μm are used for lenses, then manufacturing is simplified, but distance control between lenses and image pickup device becomes difficult
Solution Approach 1:
The spacer serves as a mediator that decouples the distance control function from the lens thickness. Instead of relying on precise control of the glass chip thickness, the spacer provides a dedicated structure with controlled thickness that determines the final distance between the lens and image pickup device. This allows the use of glass chips with broader thickness tolerances while maintaining precise distance control.
Solution Approach 2:
The optical system is segmented into distinct components: the lens (glass chip), the spacer, and the image pickup device. By separating the functions of light focusing (lens) and distance control (spacer), the system allows each component to be manufactured with appropriate tolerances. The spacer specifically handles the distance control function, enabling the use of glass chips with 0-20 μm thickness tolerance.
3Manufacturing precision
If adjustment means are added to compensate focus offset, then image mapping quality is improved, but device complexity increases
Solution Approach 1:
The spacer is introduced as a simple intermediary component that provides focus adjustment functionality. Rather than using complex mechanical adjustment mechanisms or software-based focus control, the invention uses a straightforward spacer structure that passively controls the distance between lens and sensor. This simple structural addition effectively compensates for focus offset without significantly increasing device complexity.
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 effectively compensates for focus offset, ensuring accurate image mapping and improving the overall quality of the assembled wafer level image sensors by allowing for precise control of the distance between the lens set and the photo sensor.
Implementation Method 1
a photo sensor, a lens set, and an adjustment member. The photo sensor outputs an electrical signal when induced by light
Data Source
AI summary
A wafer level image module includes a photo sensor for outputting an electrical signal upon receiving light, a lens set for focusing incident light onto the photo sensor, and an adjustment member disposed between the photo sensor and the lens set for controlling the distance between the photo sensor and the lens set to compensate the focus offset of the photo sensor for enabling the lens set to accurately focus the incident light onto the photo sensor in an in-focus manner so as to provide a high image quality.