Fingerprint Sensor Pixel Segmentation for Alignment Tolerance
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Solution Overview
Problem
The existing optical fingerprint sensing modules face challenges in achieving precise alignment between the light-shielding layer openings and microlenses, leading to poor image sensing quality due to misalignment during the bonding process, which increases manufacturing costs.
Innovation Solution
The fingerprint sensing module divides each pixel into multiple smaller light-sensing regions, allowing the image beam to illuminate part of the photosensitive regions through the microlenses, ensuring that at least one region can sense the image beam regardless of misalignment, and reduces the need for precise alignment between the light-shielding layer and microlenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light-shielding layer and microlens array are precisely aligned during bonding, then image sensing quality is improved, but manufacturing cost increases
Solution Approach 1:
Each pixel is divided into multiple physically separated light-sensing regions. This segmentation allows the image beam to illuminate at least one region even when misalignment occurs, maintaining sensing quality without requiring precise alignment between the light-shielding layer and microlens array, thereby reducing manufacturing cost.
2Ease of manufacture
If the opening of the light-shielding layer is misaligned with the microlens, then manufacturing complexity is reduced, but image sensing quality deteriorates
Solution Approach 1:
By dividing each pixel into multiple light-sensing regions, the system tolerates misalignment between the light-shielding layer opening and microlens. The image beam may miss the center but will still illuminate at least one light-sensing region, maintaining sensing quality while allowing greater manufacturing flexibility.
Solution Approach 2:
Different light-sensing regions within a pixel can independently detect light, ensuring that local misalignment does not result in complete loss of sensing capability. This local redundancy maintains overall image sensing quality even when global alignment is imperfect.
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 maintains good image sensing quality while lowering the manufacturing costs by allowing for less stringent alignment requirements, ensuring that the fingerprint sensing module can effectively capture fingerprint images even with misalignment during the bonding process.
Implementation Method 1
the microlens focuses the image beam so that the image beam penetrates the opening and focuses on the pixels of an image sensor
Implementation Method 2
each light-sensing region is adapted to receive an image beam from a user's fingerprint
Data Source
AI summary
A fingerprint sensing module including an image sensor, a microlens array and a light-shielding layer is provided. The image sensor has multiple pixels. Each of the pixels has multiple light-sensing regions physically separated. Each of the light-sensing regions is adapted to receive an image beam coming from a fingerprint of user. The microlens array is disposed above the image sensor. The microlens array includes multiple microlens. A focus region of each of the microlens covers a portion of the light-sensing regions. The light-shielding layer is disposed between the image sensor and the microlens array. The light-shielding layer has multiple openings, and the positions of the openings are corresponded to the positions of the pixels.