Display Integrated Matrix Sensor Angular Diaphragm Contrast
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Solution Overview
Problem
Existing display with integrated matrix sensors face challenges in achieving isotropic and high contrast fingerprint recordings due to limitations in reflection angle range and resolution, especially when the cover layer thickness is in the millimeter range.
Innovation Solution
The solution involves forming apertures that are smaller in length orthogonal to the offset direction than in width, and arranging them in different directions to create diaphragm groups, which limits the reflection angle range and enhances contrast, or using slits with longer lengths perpendicular to the papillary lines to direct more light intensity to sensor elements, allowing for partial recordings with reduced resolution that can be computationally corrected for isotropic and high contrast images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cover layer thickness is increased to the millimeter range, then the device structure is simplified and manufacturing is easier, but the reflection angle range becomes too broad and contrast is lost
Solution Approach 1:
The patent applies local quality by implementing angular diaphragms with specific aperture geometries at particular locations in front of sensor elements. These diaphragms have asymmetric aperture shapes (e.g., rectangular with width in offset direction and length orthogonal to offset direction) that create different acceptance angles in different directions. This local structural modification selectively limits the reflection angle range without requiring overall reduction of cover layer thickness, thereby maintaining manufacturing simplicity while restoring contrast through directional light control.
Solution Approach 2:
The angular diaphragms serve as intermediary optical elements between the cover layer and sensor elements. These diaphragms mediate the light path by selectively blocking certain reflection angles while allowing others to pass through to the sensor. The apertures in the diaphragms act as intermediaries that control the angular distribution of reflected light, enabling contrast enhancement without directly modifying the cover layer thickness or the sensor elements themselves.
2Device complexity
If the reflection angle range is not limited, then the device construction is simpler, but the recording contrast is insufficient for evaluation
Solution Approach 1:
Rather than implementing a complex overall optical system to limit reflection angles, the patent applies local quality by placing angular diaphragms with specifically designed apertures at strategic locations near sensor elements. Each diaphragm locally controls the acceptance angle for its associated sensor element, creating contrast enhancement exactly where needed without adding complex global optical components. This localized approach maintains device construction simplicity while achieving the required contrast.
Solution Approach 2:
The patent changes the angular parameter characteristics by introducing angular diaphragms with apertures that have specific width-to-length ratios and orientations. These geometric parameters of the apertures directly control the acceptance angle range in different directions. By adjusting the aperture dimensions and orientation, the system selectively modifies the reflection angle range parameter to achieve optimal contrast without requiring complex mechanical or optical adjustments.
3Measurement precision
If apertures are made smaller in length orthogonal to offset direction than in width, then isotropic contrast is achieved, but the aperture geometry becomes more complex
Solution Approach 1:
The patent deliberately employs asymmetry in the aperture geometry of the angular diaphragms. The apertures are designed with width in the offset direction and length orthogonal to the offset direction, creating an asymmetric rectangular shape rather than a symmetric circular or square aperture. This asymmetric geometry is specifically configured to produce isotropic contrast by balancing the acceptance angles in different directions. The asymmetric design is straightforward to manufacture and provides the desired optical effect without excessive complexity.
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 approach enables the production of recordings with high resolution and isotropic contrast across all sensor elements, improving the quality of fingerprint images by controlling the reflection angle range and optimizing light intensity distribution.
Implementation Method 1
The principle of frustrated total reflection (FTIR—frustrated total internal reflection) with oblique light incidence allows the papillary structure to be captured with high contrast because the light at those points where the papillary lines touch the prism surface is coupled out of the prism into the finger and is totally reflected between the papillary lines.
Implementation Method 2
The light reflected at a placement surface or platen of a cover glass beneath a finger placed thereon is directly reflected onto a matrix sensor.
Data Source
AI summary
A display with integrated matrix sensor for the optical recording of the papillary structure of at least one finger (F), in which an angular diaphragm with an aperture is arranged in each instance in front of the individual sensor elements of the matrix sensor, which aperture is offset relative to the sensor element in each instance in an offset direction (RV). Because of different dimensioning of the apertures and/or different offset directions (RV), the acceptance angle of the sensor elements of the matrix sensor is also influenced in direction orthogonal to the offset directions (RV) so that the display is suitable for making a recording having an isotropic and high contrast. The invention is also directed to a method by which, using a display according to the invention with integrated matrix sensor, an initial recording is transformed into a corrected recording having an at least approximately isotropic and high contrast.