Electro-optical Distance Meter Phase Measurement Segmentation
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Solution Overview
Problem
Conventional electro-optical distance meters require multiple frequencies for accurate distance measurement, leading to complex circuit arrangements and longer measurement times, especially when measuring distances beyond 5 km.
Innovation Solution
An electro-optical distance meter using a light emitting element, signal generators for generating proximity frequencies, a projecting optical system for intermittent modulation, a photodetection unit, a reference signal generator, a frequency converting unit, and an arithmetic control unit that calculates precise distance values by combining phase differences from multiple frequencies, allowing for efficient measurement and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If multiple modulated frequencies are used to extend measurement range, then measurement distance is improved, but device complexity increases
Solution Approach 1:
The patent segments the measurement process into two distinct phases: coarse measurement using low frequency (300 kHz) to determine the general distance range, and fine measurement using high frequency (30 MHz) to determine the precise distance. This segmentation allows the system to achieve extended measurement range without requiring complex simultaneous multi-frequency processing circuits.
Solution Approach 2:
The patent employs periodic switching between different modulated frequencies, alternating between low-frequency and high-frequency measurement cycles. This periodic action allows the use of simpler sequential processing circuits while achieving the functionality of multiple frequencies, resolving the contradiction between extended range and circuit complexity.
2Length of stationary object
If multiple modulated frequencies are used to extend measurement range, then measurement distance is improved, but measurement time increases
Solution Approach 1:
The patent performs preliminary coarse measurement using low frequency to quickly determine the distance range before conducting the fine measurement with high frequency. This preliminary action prevents unnecessary time consumption by avoiding full fine measurement cycles when the object is outside the measurable range, thus reducing total measurement time while maintaining extended measurement capability.
Solution Approach 2:
The systematic periodic switching between low-frequency and high-frequency measurement cycles optimizes the measurement process by alternating between quick range detection and precise measurement, reducing overall measurement time compared to sequential or simultaneous multi-frequency approaches.
3Length of stationary object
If heterodyne method is used for high-frequency phase measurement, then measurement range is extended, but device complexity increases
Solution Approach 1:
The patent extracts and removes the complex frequency conversion (heterodyne) circuitry from the system by adopting direct phase measurement methods. Instead of converting high-frequency signals to lower frequencies for measurement, the system directly measures the phase of the returned high-frequency signal, thereby extending measurement range while eliminating the source of circuit complexity.
Solution Approach 2:
The patent replaces the mechanical/electrical frequency conversion mechanism (heterodyne method) with a direct electronic phase detection method. This substitution eliminates the need for complex frequency mixing circuits while achieving the same goal of extended measurement range through direct high-frequency phase measurement.
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 enables high measurement efficiency, reduces measurement time, enhances accuracy, and allows for long-distance measurement without the need for additional modulated frequencies, while simplifying the electrical circuit and improving the signal-to-noise ratio.
Implementation Method 1
a light emitting element for emitting a distance measuring light
Implementation Method 2
a photodetection unit for receiving a reflected distance measuring light from an object to be measured and producing an intermittent photodetection signal
Implementation Method 3
a frequency converting unit for performing frequency conversion by mixing the intermittent photodetection signals from the photodetection unit and the reference frequency signals
Data Source
AI summary
The invention relates to an electro-optical distance meter, which projects a modulated measuring light to an object to be measured, receives a reflected measuring light from the object to be measured and measures a distance to the object to be measured by a phase difference between the measuring light and the reflected light. With the electro-optical distance meter, it is possible to efficiently prepare signals required for measurement and to perform measurement within a short time.