TOF Range Finder Waveform Design for Linearity and Power Efficiency
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Solution Overview
Problem
Current TOF range finders face challenges in achieving high incident intensity of reflected light while maintaining a linear relationship between phase delay and distance, often requiring higher emission power and suffering from non-linear relationships due to suboptimal modulated light waveforms.
Innovation Solution
The use of a TOF range finder with a light source emitting modulated light having a periodic waveform that includes a fundamental wave and specific multiple waves, such as odd and even multiple waves, to improve the linear relationship between phase delay and distance, and to secure high incident intensity with reduced emission power, utilizing a half-wave rectified waveform or its approximation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional modulated light waveforms (e.g., rectangular pulses) are used, then the TOF range finder can perform distance measurement, but the incident intensity of reflected light is low requiring higher emission power and the relationship between phase delay and distance becomes non-linear
Solution Approach 1:
The patent changes the waveform parameter of the modulated light from conventional rectangular pulses to a periodic waveform with specific characteristics (containing fundamental wave or odd multiple waves for only one frequency component and even multiple waves for at least one frequency component). This parameter change in the light waveform simultaneously improves the linearity of phase delay-distance relationship and increases incident intensity of reflected light, thereby reducing required emission power.
2Illumination intensity
If emission power is increased to secure high incident intensity of reflected light, then incident intensity improves, but the relationship between phase delay and distance becomes non-linear and energy consumption increases
Solution Approach 1:
The patent changes the waveform parameter of the modulated light to a periodic waveform containing specific frequency components (fundamental wave or odd multiple waves for one frequency component, and even multiple waves for at least one frequency component). This parameter change enables high incident intensity of reflected light to be achieved with reduced emission power while maintaining linear phase delay-distance relationship.
3Use of energy by moving object
If rectangular pulse waveforms are used for modulated light, then the system can operate with simple waveforms, but the incident intensity of reflected light is low and emission power must be increased
Solution Approach 1:
The patent changes the waveform parameter from simple rectangular pulses to a periodic waveform with specific spectral characteristics (containing fundamental wave or odd multiple waves for only one frequency component and even multiple waves for at least one frequency component). This parameter change increases the incident intensity of reflected light while reducing the required emission power, improving energy efficiency.
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 enhances the linear relationship between phase delay and distance while achieving high incident intensity of reflected light with less emission power, improving the efficiency and accuracy of distance measurement.
Implementation Method 1
a light source which emits modulated light toward a distance measurement object... an image sensor which has a plurality of pixels to detect, for each pixel, the incident intensity of incident light
Implementation Method 2
a phase difference detecting unit which detects the phase difference between emitting modulated light from the light source and reflected modulated light... based on the quantity of charges stored in the image sensor
Data Source
AI summary
The present invention provides a TOF range finder. A TOF range finder 1 includes a light source 2, which emits modulated emitting light La, a light source control unit 51, which drives the light source 2, an image sensor 10, which detects modulated reflected light, and a distance calculating unit 53, which calculates the distance to a distance measurement object 7 based on the phase difference between emitting light La and reflected light. The modulated light is generated in the form of a periodic waveform which contains an only odd multiple wave frequency component and at least one even multiple wave frequency component.