Optical Sensor With Apertures and Reflective Layer for Display Integration
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Solution Overview
Problem
Conventional optical fingerprint sensors face challenges in integrating light conditioning structures into small spaces, leading to image blurring and compromised image quality, while capacitive sensors struggle to detect fingerprints through thick cover glass, requiring cutouts that detract from device aesthetics and functionality.
Innovation Solution
An optical sensor design featuring a transparent layer with apertures and a reflective layer below, which restricts light angles to minimize sensor thickness and eliminate trade-offs between cover layer thickness, image blurring, and display image quality, allowing for effective fingerprint detection without mechanical buttons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical elements are used to condition light before reaching sensor elements, then image quality is improved, but the height of the sensor increases making it difficult to fit into limited display stack space
Solution Approach 1:
The patent transitions from a conventional vertical stacking arrangement of optical elements to a planar integration approach where the optical element is formed within the same substrate layer as the sensor array. This dimensional reorganization allows light conditioning to occur in-plane rather than requiring additional vertical space, resolving the contradiction between image quality and sensor height.
Solution Approach 2:
The patent combines the optical element and sensor array into a single integrated structure formed in the same substrate. By merging these previously separate components into one unified element, the design eliminates the need for additional height while maintaining the light conditioning function, thus resolving the contradiction between image quality and compact form factor.
2Reliability
If light conditioning structures are placed at or above the active display matrix, then fingerprint detection capability is improved, but cover layer thickness must be reduced which causes image blurring
Solution Approach 1:
The patent relocates the light conditioning structure from the vertical dimension (above the display matrix requiring thin cover glass) to the planar dimension (within the same substrate layer as the sensor). This allows the conditioning structure to function effectively without compromising cover glass thickness, thereby preventing image blurring while maintaining fingerprint detection capability.
Solution Approach 2:
The patent creates an optical path that effectively copies the light conditioning function to a different location within the same substrate plane. By forming the optical element in the same substrate as the sensor array rather than requiring a separate cover layer, the design achieves the light conditioning effect without the negative consequences of thin cover glass.
3Shape
If capacitive sensors are used to detect fingerprints through thick cover glass, then device aesthetics are improved, but sensing capability deteriorates requiring cutouts that compromise device functionality
Solution Approach 1:
The patent merges the optical sensing function with the display substrate, creating an integrated structure where the sensor array and optical elements are formed in the same substrate layer. This integration allows the sensor to detect fingerprints through thick cover glass without requiring cutouts, thereby maintaining both device aesthetics and sensing capability simultaneously.
Solution Approach 2:
The patent replaces the capacitive sensing mechanism with an optical sensing mechanism that uses light reflection and detection. This substitution enables fingerprint detection through thick cover glass without requiring mechanical cutouts or buttons, resolving the contradiction between maintaining device aesthetics and achieving reliable sensing capability.
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 enables reliable fingerprint imaging through thick cover glass without compromising image quality or device aesthetics, providing a compact and efficient solution for mobile devices.
Implementation Method 1
a reflective layer formed in the same substrate as the sensor array and configured to reflect light onto the sensor elements
Data Source
AI summary
Systems and methods for optical imaging are disclosed. An optical sensor for imaging a biometric input object on a sensing region includes a transparent layer having a first side and a second side opposite the first side; a first set of apertures disposed above the first side of the transparent layer; a reflective layer disposed below the second side of transparent layer configured to receive light transmitted through the first set of apertures and to reflect the received light; and a plurality of detector elements positioned to detect the reflected light.