Angled Reflective Material Sensor to Avoid Window Reflection
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Solution Overview
Problem
Existing non-immersed precipitation sensors face challenges in accurately sensing reflective materials like snow, sleet, frost, and dry dust due to poor sensitivity and surface reflection issues, particularly in cold environments and with heated glass solutions that are uncomfortable for vehicle occupants.
Innovation Solution
A sensor design utilizing two radiation emitters on either side of a radiation detector, angled to avoid surface reflection, with a temperature sensor and controller to differentiate between winter and non-winter precipitation, employing LED radiation sources and photo transistors or diodes to detect reflected radiation effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radiation sensor is positioned to receive reflected radiation from the transparent window surface, then the sensor can detect reflective materials, but surface reflection from the window itself causes inaccurate sensing
Solution Approach 1:
The radiation emitter and radiation sensor are positioned asymmetrically relative to the transparent window surface. The emitter is offset from the normal axis, and the sensor is positioned to receive radiation at a different angle than the emitter's incidence angle, breaking the symmetry that would cause direct reflection into the sensor and enabling discrimination between surface reflection and material reflection
Solution Approach 2:
The solution moves the sensing problem from a one-dimensional normal-incidence geometry to a two-dimensional angular geometry. By positioning the emitter and sensor at different angles and locations, the system creates a spatial configuration where surface reflection and material reflection follow different paths, allowing the sensor to distinguish between them
2Measurement precision
If the glass is heated to melt snow next to the glass, then the sensor can detect snow, but vehicle occupants become uncomfortable
Solution Approach 1:
The patent replaces the thermal field approach (heating the glass) with an optical field approach (reflective sensing). Instead of using heat to melt snow and enable detection, the system uses radiation emitters and sensors to detect the reflective properties of snow directly, eliminating the need for thermal processing and associated occupant discomfort
Solution Approach 2:
The system changes the detection parameter from thermal state (melted snow) to optical property (reflectivity). By measuring the reflective characteristics of snow at its natural temperature state rather than requiring it to be melted, the system achieves snow detection without thermal intervention
3Measurement precision
If a single radiation emitter is used, then the device is simple, but sensitivity for detecting reflective materials is poor
Solution Approach 1:
The radiation emission function is segmented into multiple independent emitters positioned at different locations and angles. This segmentation allows each emitter to probe different aspects of the reflective material, and their combined signals provide enhanced detection sensitivity and material characterization capability
Solution Approach 2:
Multiple radiation emitters and sensors are merged into a single integrated sensor assembly. The emitters are positioned to illuminate the transparent window from different angles, and their reflected radiation is collected by corresponding sensors, combining their detection capabilities into one unified device
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
The solution provides enhanced sensitivity for winter precipitation and dry reflective materials, improving accuracy and comfort by avoiding heating-related issues, and can function across various environments and applications, including motorized transportation and infrastructure projects.
Implementation Method 1
radiation is emitted at a deviation from normal to the transparent window... oriented to radiate through a transparent material such as glass, at an angle that does not cause a surface reflection back to the radiation sensor
Implementation Method 2
The radiation detector is located to receive reflected radiation from the reflective material along a second axis
Implementation Method 3
A radiation source such as a LED is oriented to radiate through a transparent material
Implementation Method 4
A radiation sensor such as but not limited to a photo transistor, photo diode or light dependent resister adjacent to the radiation source senses the radiation reflection
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Described herein is a sensor for sensing reflective material. The sensor includes a housing with a transparent window and a sensor mount located in the housing and angled away from a housing wall. A radiation emitter is mounted in the sensor mount and emits radiation along an axis through the transparent window which has an amount of the reflective material located thereon. A radiation detector is mounted in the sensor mount and located adjacent the radiation emitter. The radiation detector is located to receive reflected radiation from the reflective material along another axis. The first axis is angled towards the second axis.