Fingerprint Sensor Pixel Aperture Layout for Short-Distance Imaging
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Solution Overview
Problem
Electronic devices with fingerprint sensors face a resolution decrease when the distance between the finger and the imaging unit is reduced, leading to compromised image quality.
Innovation Solution
The electronic device incorporates a plurality of pixels with distinct optical configurations, including first lenses, light shielding films, and photoelectric conversion units, where the shape and position of holes in the light shielding films differ between pixels, along with the use of reflow lenses, diffraction lenses, and plasmon filters, to maintain resolution and improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the distance from the finger to be imaged to the imaging unit is decreased, then the device can be made thinner and identification speed is improved, but the resolution of the image captured through the optical system is reduced
Solution Approach 1:
The patent applies local quality by making each pixel have a different hole shape in the light shielding film, optimized for its specific position in the array. Central pixels have circular holes while peripheral pixels have elliptical holes, allowing each pixel to optimally capture light from its specific viewing angle while maintaining high resolution even at reduced imaging distances
Solution Approach 2:
The patent transitions from a single uniform hole shape to multiple differentiated hole shapes across the pixel array. By varying the hole shape (circular, elliptical, etc.) according to pixel position, the system adds a dimensional aspect of spatial variation that compensates for the reduced depth of field caused by shorter imaging distances
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 configuration enables the suppression of resolution decrease even at closer distances, enhancing image quality and sensitivity while allowing for accurate identification of human fingers and distinguishing them from artificial objects.
Implementation Method 1
a first lens that collects incident light
Implementation Method 2
a photoelectric conversion unit configured to photoelectrically convert the incident light having passed through the first hole
Implementation Method 3
At least one element in a second optical system including the first lens that collects the incident light into the first hole may be a diffraction lens
Implementation Method 4
The first hole may include a plasmon filter that has a plurality of holes smaller than the opening
Data Source
AI summary
Provided is an electronic device that includes a plurality of pixels, each of at least two pixels of the plurality of pixels includes a first lens that collects incident light, a first light shielding film portion having a first hole through which a part of the incident light that has been collected passes, and a photoelectric conversion unit that converts the incident light having passed through the first hole. A shape of the first hole with respect to the first light shielding film portion is different between a first pixel among the at least two pixels and a second pixel different from the first pixel among the at least two pixels.