Time of Flight Sensor Coverage Factor Evaluation
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Solution Overview
Problem
Existing touch screen technologies, such as those using infrared sensors, struggle to accurately determine the transverse position and motion of objects relative to the screen, as they are influenced by reflectance and intensity variations, which can lead to inaccurate distance measurements and fail to provide precise spatial information.
Innovation Solution
A method utilizing time of flight sensors to evaluate a coverage factor by constructing a reference curve during calibration, allowing for the detection of transverse position and motion by analyzing the ratio of acquired photon flux intensity to reference intensity, and employing multiple sensors to determine spatial coordinates and movement direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If infrared sensors are used to detect object position, then the detection function is provided, but the measurement precision deteriorates due to reflectance and intensity variations
Solution Approach 1:
The patent replaces traditional infrared intensity-based sensing with time-of-flight (ToF) measurement. Instead of measuring light intensity that varies with reflectance, the system measures the time it takes for light to travel to and from the object, which is independent of the object's reflectance properties. This substitution of measurement principle eliminates the fundamental limitation of intensity-based sensors.
Solution Approach 2:
The patent changes the measurement parameter from light intensity to time of flight. By measuring the temporal characteristic (time) rather than the amplitude characteristic (intensity), the system achieves accuracy that is independent of the object's optical properties such as reflectance, color, or surface texture.
2Measurement precision
If single time of flight sensor is used to measure distance, then the distance measurement accuracy is improved, but the ability to detect transverse position and motion deteriorates
Solution Approach 1:
The patent divides the sensing function across multiple time-of-flight sensors arranged in an array. Each sensor measures the time of flight for photons traveling to its specific location, and by comparing measurements across the array, the system can determine both distance and transverse position. This segmentation of the sensing aperture enables multidirectional measurement capabilities.
Solution Approach 2:
The patent transitions from one-dimensional distance measurement (single sensor) to two-dimensional position detection (sensor array). By adding spatial distribution of sensors, the system gains the ability to detect transverse position in addition to distance, effectively adding a dimensional aspect to the measurement capability.
3Measurement precision
If multiple time of flight sensors are deployed to detect transverse position, then the spatial detection capability is improved, but the device complexity increases
Solution Approach 1:
The patent makes each time-of-flight sensor in the array perform multiple functions: distance measurement, transverse position detection, and motion detection. By using the same sensor type for all these purposes and processing the data through a unified algorithm, the system achieves multidimensional sensing without proportionally increasing complexity.
Solution Approach 2:
The patent enables the sensor array to self-calibrate and self-characterize by having each sensor measure the time of flight to known reference positions. The system automatically builds lookup tables and calibration data without external intervention, reducing the complexity of manual setup and maintenance.
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
Enables accurate detection of object position and motion, independent of reflectance, providing both quantitative and qualitative proximity measures, and precise spatial location using weighted barycenters of coverage factors from multiple sensors.
Implementation Method 1
The circuit thus measures the time of flight of the photons along a path 18 going from the transmitter 10 to the object 16 and returning to the detector 14. The time of flight is proportional to the distance between the object and the detector
Implementation Method 2
A photon detector 14 is arranged on the printed circuit board close to the transmitter 10 for receiving photons reflected from a target object placed in the cone 16
Data Source
AI summary
A method is for evaluating a coverage factor of a photon emission cone of a time of flight sensor. The method may include the steps of assigning a reference curve to the sensory providing a photon flux intensity as a function of time of flight; and acquiring a time of flight and a corresponding flux intensity with the sensor. The method may also include reading the intensity provided by the reference curve for the acquired time of flight, and providing an indication of the coverage factor based on the ratio between the acquired intensity and the read intensity.