Wafer-Level Lens Structure for Contact Image Sensor Modules
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Solution Overview
Problem
Contact Image Sensor (CIS) modules using rod lens arrays face limitations in scalability, image quality, cost, stringent size demands due to short depth of field, and sensitivity to particles, which affect imaging performance and manufacturing yield.
Innovation Solution
A wafer-level lens structure for CIS modules, comprising a printed circuit board with an image sensor, a first lens array of resin material with controlled curvature, and an aperture array to focus light onto an optoelectronic conversion array, eliminating the need for rod lenses and allowing for improved focus control and reduced module height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If rod lens array is used for focusing light, then light focusing function is achieved, but the focusing length is limited by rod material and rod diameter making it difficult to scale down
Solution Approach 1:
The patent changes the lens material from traditional rod lens material to resin material with specific refractive index (1.1-1.9), and changes the lens shape from rod form to cover lens form with controllable curvature. This allows independent optimization of focusing length and module size without being constrained by rod diameter and material properties.
Solution Approach 2:
The patent uses cover lenses with curved surfaces (first curved face and second curved face) instead of rod lenses. The curvature of these surfaces can be precisely controlled to achieve the desired focusing length, enabling both compact module size and accurate focusing performance.
2Manufacturing precision
If rod lens array is used, then light focusing is achieved, but image quality is not satisfactory and cost is high due to injection molding requirements
Solution Approach 1:
The patent combines the lens array and aperture array into a single integrated wafer-level structure. This integration eliminates the need for separate injection molding of rod lenses and reduces assembly steps, thereby lowering manufacturing cost while maintaining or improving image quality through precise optical design.
Solution Approach 2:
The patent uses wafer-level processing to create replicated lens structures, where a master wafer pattern is copied across multiple lenses simultaneously. This approach enables high-precision image quality with cost-effective mass production, avoiding the high costs associated with individual rod lens injection molding.
3Stability of the object's composition
If rod lens is used, then focusing is achieved, but depth of field is short requiring more stringent size demands on housing
Solution Approach 1:
The patent changes the optical parameters by using resin material with specific refractive index ranges (1.1-1.9) and optimizing the curvature of the cover lens surfaces. These parameter changes enable extended depth of field while maintaining compact housing dimensions, resolving the contradiction between DOF and size constraints.
4Manufacturing precision
If object distance is set equal to focal distance for optimal imaging, then imaging quality is optimized, but design flexibility is reduced
Solution Approach 1:
The patent creates a dynamic optical system where the focusing length can be independently adjusted from the object distance through curvature control of the cover lenses. This dynamic design flexibility allows optimal imaging quality to be achieved while accommodating various object distances and application requirements.
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
Enhances imaging quality, depth of field, and reduces manufacturing complexity and costs, while allowing for more flexible design and improved yield by eliminating the constraints of equal object and focal distances and minimizing particle impacts.
Implementation Method 1
each of first cover lens having a first curved face to focus the external image light to the optoelectronic conversion array
Implementation Method 2
the light sensor converts the photonic signal into corresponding electric signal
Data Source
AI summary
A wafer-level lens structure for contact image sensor (CIS) module includes a printed circuit board (PCB) and an image sensor electrically connected to the PCB and comprising a circuit area and a light sensitive area. The light sensitive area comprises an optoelectronic conversion array, a first lens array arranged on the optoelectronic conversion array and comprising a plurality of first cover lens, each of first cover lens having a first curved face to focus the external image light to the optoelectronic conversion array, and an aperture array arranged on the first lens array and comprising a plurality of apertures to expose the first curved face, the aperture array controlling a light amount passing through the cover lens. The first curved face of the cover lens has such a curvature that a predetermined focus point can be achieved by the plurality of first cover lens.