Optical Sensor Uniform Vein Imaging via Light Guide Plate
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Solution Overview
Problem
Conventional optical sensors for vein authentication face challenges such as non-uniform light irradiation and reduced resolution due to absorption or scattering in parts other than the vein, and the difficulty in achieving uniform light distribution in reflection type sensors.
Innovation Solution
The optical sensor incorporates a light irradiation unit with a light guide plate and a viewing angle control plate, such as a louver array film or fiber optic plate, to ensure uniform light irradiation and control the direction of reflected light, allowing for high-resolution image acquisition of vein patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional reflection type sensor is used with the light source unit disposed around the light receiving unit, then the sensor can perform vein authentication, but uniform light irradiation cannot be achieved
Solution Approach 1:
A light guide plate is introduced as an intermediary component between the light source and the measurement object. The light guide plate receives light from the light source unit and distributes it uniformly across the measurement surface through internal reflection and light scattering mechanisms, thereby achieving uniform illumination without requiring complex multi-source arrangements
Solution Approach 2:
The light guide plate incorporates a light diffusing layer or micro-structured surface in specific regions to locally modify light distribution characteristics. This allows different zones of the light guide plate to have different light transmission properties, optimizing uniformity across the entire measurement area while maintaining a simple overall structure
2Reliability
If absorption or scattering in parts other than the vein is large in the measurement object, then the transmission type sensor cannot obtain sufficient light, but the reflection type sensor suffers from non-uniform light irradiation
Solution Approach 1:
The light guide plate serves as a mediator that decouples the light source positioning from the illumination pattern. By controlling light propagation within the guide plate through total internal reflection and controlled scattering at the measurement surface, it ensures uniform illumination regardless of variations in light absorption and scattering properties of the measurement object
Solution Approach 2:
The invention transitions from a point-source or ring-source illumination model to a planar illumination model using the light guide plate. This dimensional change allows light to be distributed across a two-dimensional surface area, achieving uniformity that cannot be obtained with conventional one-dimensional light source arrangements
3Measurement precision
If the light source unit is disposed around the light receiving unit in a reflection type sensor, then vein authentication can be performed, but high-resolution image information cannot be obtained
Solution Approach 1:
The light guide plate acts as an optical intermediary that provides a uniform, extended illumination surface. This uniform lighting condition reduces shadows and hot spots, thereby improving the contrast and resolution of the captured vein pattern images without requiring complex multi-angle or multi-source illumination arrangements
Solution Approach 2:
The invention changes the illumination parameter from concentrated point-source lighting to distributed surface lighting. This parameter change in light distribution uniformity directly improves image quality and resolution by ensuring consistent illumination across the entire measurement field, eliminating the need for complex light source geometries
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 uniform light irradiation to the measurement object and enhances the resolution of vein pattern images, effectively addressing the limitations of conventional sensors.
Implementation Method 1
the light emitted by the light source spreads throughout the inside of the light guide plate
Implementation Method 2
a viewing angle control plate for limiting the direction of the reflected light from the measurement object in a predetermined direction
Implementation Method 3
a light detection unit for acquiring image information indicating the distribution of the reflected light obtained through the viewing angle control plate
Data Source
AI summary
Uniform light irradiation to the measurement object is realized, and it is possible to obtain high resolution image information, to provide a reflective optical sensor. An optical sensor comprises a light irradiation unit for performing uniform light irradiation with respect to the measurement object, the viewing angle control plate for limiting the direction of the reflected light in the measurement object to the predetermined direction, a light detecting unit for acquiring image information showing the distribution of the reflected light obtained through the viewing angle control plate. The viewing angle control plate is a louver array film or a fiber optic plate.