Optical Filter Layer for Display Fingerprint Sensor Lag Reduction
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Solution Overview
Problem
Fingerprint recognition in display areas faces inefficiencies due to lag issues when using point light sources, leading to prolonged fingerprint collection times and reduced efficiency, as the photosensor is affected by light information from the first point light source when the second is lit, necessitating a wait for the lag to end before re-lighting.
Innovation Solution
A fingerprint identification assembly with multiple point light sources emitting different colored signals, where an optical filter layer on the light-sensitive units filters out the first signal light from the non-imaging area, allowing the second signal light to irradiate and complement the non-imaging area, enabling simultaneous lighting of the second point light source without waiting for lag to end, thus reducing the interval between lightings and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the second point light source is lit immediately after the first point light source, then the fingerprint collection efficiency is improved, but the photosensor is affected by residual light information from the first point light source causing lag
Solution Approach 1:
The optical filter layer is divided into multiple filter units, each corresponding to a specific point light source. The first filter unit is positioned between the first point light source and the photosensor to block residual light, while the second filter unit is positioned between the second point light source and the photosensor. This segmentation allows independent control of light paths for each point light source, enabling the photosensor to accurately capture fingerprint information without interference from previous light sources.
2Illumination intensity
If the first point light source continues to emit light, then the imaging area is well-illuminated, but the non-imaging area receives excessive light causing lag and requiring a wait period
Solution Approach 1:
The first filter unit selectively extracts and blocks light from the first point light source that would otherwise reach the non-imaging area of the photosensor. By positioning the filter unit between the first point light source and the photosensor's non-imaging area, the harmful light is removed while the imaging area remains properly illuminated. This allows the system to transition to the second point light source without requiring a wait period, as the residual light is actively blocked rather than passively waiting to dissipate.
3Quantity of substance
If multiple point light sources are used to cover the entire fingerprint area, then the fingerprint collection completeness is improved, but the interval between lightings increases due to lag
Solution Approach 1:
The optical filter layer acts as an intermediary between the multiple point light sources and the photosensor. Each filter unit in the optical filter layer is specifically designed to block light from its corresponding point light source when that light source is not actively being used. This intermediary structure prevents residual light from any point light source from reaching the photosensor, thereby eliminating lag effects and allowing the system to quickly transition between multiple point light sources to achieve complete fingerprint area coverage without increasing the interval between lightings.
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 solution eliminates the lag effect, significantly reducing the interval between lightings of point sources and enhancing fingerprint collection efficiency by allowing immediate lighting of the second point light source, while also filtering out ambient light to improve recognition accuracy.
Implementation Method 1
an optical filter layer provided on a light entry side of the light sensitive unit, wherein the optical filter layer comprises a plurality of first filter units, the first filter unit corresponds to a non-imaging area that is formed on the light sensitive units after the first point light source is lit, for preventing the first signal light reflected by the finger from irradiating at least a predetermined portion of the non-imaging area of the light sensitive units, and allowing the second signal light reflected by the finger to irradiate the non-imaging area of the light sensitive units
Implementation Method 2
a plurality of light sensitive units configured to sequentially receive the first signal light and the second signal light reflected by a finger to identify a fingerprint
Data Source
AI summary
A fingerprint identification assembly is disclosed. The fingerprint identification assembly includes first point light sources for emitting first signal light; second point light sources for emitting second signal light after the first point light source emits the first signal light; light sensitive units configured to sequentially receive the first signal light and the second signal light reflected by a finger; and an optical filter layer provided on a light entry side of the light sensitive unit. The optical filter layer includes first filter units, the first filter unit corresponds to a non-imaging area that is formed on the light sensitive units after the first point light source is lit, for preventing the first signal light reflected by the finger from irradiating the non-imaging area of the light sensitive units, and allowing the second signal light reflected by the finger to irradiate the non-imaging area of the light sensitive units.