Overlapping Collimator Structure for Low-Crosstalk Image Capture
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Solution Overview
Problem
Optical identification apparatuses for biological characteristics face challenges in capturing high-quality images due to disorganized light beams reflected from objects, leading to poor identification results and ineffective crosstalk reduction.
Innovation Solution
The image capturing apparatus incorporates a collimator with overlapping collimating elements, each comprising a transparent substrate and a light absorbing layer with light passing openings, where the thickness ratio of the collimating elements and the spacing between light passing openings are optimized to absorb large-angle light beams, reducing crosstalk and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical identification apparatus uses a light source and sensor without a collimator, then the structure is simple, but the reflected light beams are disorganized leading to poor image quality and crosstalk
Solution Approach 1:
The collimator is divided into multiple collimating elements (first collimating element and second collimating element) with each element containing light absorbing layers with light passing openings. This segmentation allows the system to collimate light beams effectively while managing complexity through modular design, resolving the contradiction between image quality improvement and structural simplicity.
Solution Approach 2:
The collimator acts as an intermediary component positioned between the light source and the sensor. It mediates the light paths by collimating reflected light beams from the object, ensuring organized light transmission to the sensor. This intermediary structure improves image quality without requiring complete redesign of the entire optical system.
2Object-affected harmful factors
If the collimator uses thick transparent substrates to absorb large-angle light beams, then crosstalk is reduced, but the device size increases
Solution Approach 1:
Instead of increasing substrate thickness in one dimension, the patent uses multiple thin transparent substrate layers stacked in multiple dimensions. The first and second collimating elements are arranged in sequence, with each containing light absorbing layers that collectively absorb large-angle light beams. This multi-dimensional arrangement achieves effective crosstalk reduction while maintaining a compact overall device size.
Solution Approach 2:
The collimator combines multiple materials with different optical properties: transparent substrates that allow light transmission and light absorbing layers that selectively absorb large-angle light beams. This composite structure achieves effective crosstalk reduction through material properties rather than increasing overall device dimensions.
3Illumination intensity
If the light passing openings are widely spaced to allow more light through, then image brightness is improved, but crosstalk between adjacent sensing areas increases
Solution Approach 1:
The light absorbing layers are strategically positioned at specific locations within the collimating elements, creating local quality variations. The light passing openings are arranged with specific spacing patterns, and the light absorbing layers are placed to selectively absorb light beams at certain angles while allowing other light beams to pass. This local quality control enables simultaneous achievement of adequate brightness and crosstalk reduction.
Solution Approach 2:
The patent optimizes parameters including the spacing between light passing openings (S), the width of light passing openings (W), and the thickness of transparent substrates (T1, T2). By carefully adjusting these parameters to satisfy specific mathematical relationships, the system achieves optimal balance between light transmission (brightness) and crosstalk reduction.
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 effectively addresses the issue of crosstalk, enhancing the signal-to-noise ratio and improving the identification capability of the image capturing apparatus by absorbing large-angle light beams and ensuring high-quality image capture.
Implementation Method 1
Each of the collimating elements includes a transparent substrate and a light absorbing layer disposed on the transparent substrate. The light absorbing layer includes a plurality of light passing openings. Spacing between the light passing openings is S. A width of each of the light passing openings is W, and W1, a transparent substrate thickness of a second collimating element in the collimating elements is T2, and the image capturing apparatus satisfies: T1/W≤0.5 and T2/S≤0.5
Data Source
AI summary
An image capturing apparatus including a cover plate, a light source, a sensor, and a collimator is provided. The light source and the sensor are located on the same side of the cover plate. The collimator is disposed between the cover plate and the sensor, and the collimator includes collimating elements overlapping with each other. Each collimating element includes a transparent substrate and a light absorbing layer disposed on the transparent substrate. The light absorbing layer includes a plurality of light passing openings. The light passing openings expose sensing areas of the sensor. Spacing between the light passing openings is S. A width of each light passing opening is W, and W<S. A transparent substrate thickness of a first collimating element in the collimating elements is T1. A transparent substrate thickness of a second collimating element in the collimating elements is T2. The image capturing apparatus satisfies:0.3×WS×T1≤T2≤T1.