Lens Guide Maintains Optical Air Gap in Under-Display Fingerprint Sensors
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Solution Overview
Problem
Conventional display devices fail to maintain a sufficient air gap between the optical lens and the display panel, leading to degraded performance of the fingerprint sensor due to compression of the adhesive layer during manufacturing, which affects the recognition of fingerprints.
Innovation Solution
Incorporating a lens guide between the adhesive layer and the optical lens to maintain a specific distance, ensuring the air gap is preserved and the adhesive layer does not intrude into the optical lens area, thereby enhancing the fingerprint sensor's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adhesive layer is used to attach the fingerprint sensor to the display panel, then the fingerprint sensor can be securely mounted, but the adhesive layer compresses during manufacturing and reduces the air gap between the optical lens and display panel, degrading fingerprint recognition performance
Solution Approach 1:
A lens guide structure is introduced as an intermediary component between the adhesive layer and the optical lens. The lens guide includes a lens guide body attached to the display panel and a lens guide protrusion that extends toward the optical lens, maintaining a predetermined distance. This intermediary structure prevents the adhesive layer from directly contacting the optical lens, thereby preserving the air gap while still enabling secure attachment of the fingerprint sensor assembly.
2Strength
If the adhesive layer is applied between the lens frame and display panel, then the components can be bonded together, but the adhesive layer intrudes into the optical lens area and compromises the optical path
Solution Approach 1:
The bonding interface is segmented into two distinct zones: a first bonding area where the adhesive layer bonds the lens frame to the display panel, and a second bonding area where the lens guide protrusion prevents adhesive intrusion into the optical lens region. This segmentation allows the adhesive to provide necessary bonding strength while being physically restricted from contaminating the optical path by the lens guide structure.
Data Source
AI summary
A display device includes: a display panel including a display area; a fingerprint sensor disposed under the display panel overlapping the display area, the fingerprint sensor including: an optical lens; a lens frame disposed under the optical lens; an image sensor disposed under the lens frame and exposed toward the optical lens through an opening formed in the lens frame; and an adhesive layer disposed between the lens frame and the display panel and surrounding the optical lens in a plan view, and attaching the lens frame and the display panel to each other; and a lens guide disposed between the adhesive layer and the optical lens in the plan view, and configured to maintain a distance between a lower surface of the display panel and an upper surface of the optical lens, the lens guide protruding from an upper surface of the lens frame toward the display panel.