Resonant Laser Driver for Time of Flight Camera Power Efficiency
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Solution Overview
Problem
Time of flight camera systems face challenges in reducing power consumption and heat dissipation, which leads to increased size and cost, making them less efficient and less suitable for various applications.
Innovation Solution
A method and device for a time of flight camera system that involves illuminating an environment with light of a specific wavelength, using high-speed signal control to achieve resonance between the light source and driver electronics, and calculating distance using a controller, while optimizing power efficiency by finding the resonant frequency of the laser driver system to minimize power consumption and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional pulsed laser drivers are used to illuminate the environment in a time of flight camera system, then the system can achieve adequate illumination and distance measurement capability, but the power consumption increases and heat dissipation increases requiring larger heat sinks
Solution Approach 1:
The patent applies resonance principles to the electrical driving system by tuning the driver electronics to operate at the resonant frequency of the laser diode's electrical circuit. This resonant operation allows the system to achieve maximum illumination output with minimum power input, as the resonant oscillation efficiently transfers energy to the laser diode without requiring excessive driving power. The resonant frequency is determined by the electrical characteristics (inductance, capacitance, resistance) of the laser driver circuit, and operating at this frequency minimizes power losses and maximizes conversion efficiency.
Solution Approach 2:
The patent changes the operating parameters of the laser driver by dynamically adjusting the driving frequency to match the resonant frequency of the system. This parameter optimization transforms the driver from a conventional fixed-frequency pulsed driver to a resonant-frequency adaptive driver. By continuously monitoring and adjusting the operating frequency to maintain resonance, the system achieves optimal power efficiency while maintaining reliable illumination capability across varying operating conditions.
2Illumination intensity
If higher power is supplied to the light source to improve illumination and measurement accuracy, then the illumination intensity and measurement precision improve, but heat dissipation increases requiring larger heat sinks and increasing system size
Solution Approach 1:
The patent utilizes resonant oscillation in the electrical driving circuit to maximize the conversion efficiency of electrical energy to optical energy. By operating at the resonant frequency determined by the circuit's electrical characteristics, the system achieves maximum light output intensity with minimum electrical power input. This resonant operation minimizes energy losses as heat, thereby reducing the heat generation that would otherwise require large heat sinks, thus maintaining compact system size while achieving high illumination intensity.
Solution Approach 2:
The patent employs periodic pulsed driving at the resonant frequency to illuminate the scene. Instead of continuous high-power operation, the system uses precisely timed periodic pulses that exploit the resonant build-up of energy in the electrical circuit. Each pulse delivers maximum energy transfer to the laser diode, producing high-intensity light output only when needed for measurement, while allowing the system to dissipate minimal heat between pulses, thereby reducing overall heat sink requirements.
3Device complexity
If conventional non-resonant driver electronics are used, then the system design is simpler without resonance tuning requirements, but power consumption increases and overall system efficiency decreases
Solution Approach 1:
The patent introduces resonance tuning into the driver electronics design, which requires determining and operating at the specific resonant frequency of the laser diode's electrical circuit. This involves characterizing the circuit's electrical characteristics (inductance L, capacitance C, resistance R) and calculating the resonant frequency using the formula f = 1/(2π√(LC)). The driver electronics are designed to generate pulses at this specific frequency, which maximizes energy transfer efficiency. While this adds some design complexity compared to conventional fixed-frequency drivers, it dramatically improves power efficiency by minimizing energy losses and maximizing optical output for a given electrical input.
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 approach reduces power consumption and heat dissipation, allowing for a more compact and cost-effective time of flight camera system that can be used in various applications, including interactive video games and security, by achieving efficient power usage and minimizing the size of the heat sink required.
Implementation Method 1
a light source for illuminating an environment including an object with light of a first wavelength
Implementation Method 2
controlling the light source with a high speed signal at a clock frequency, whereby the light source and driver electronics system is at resonance; selecting the clock frequency, whereby the light source and driver electronics system is at resonance
Implementation Method 3
an image sensor for measuring time the light has taken to travel from the light source to the object and back
Data Source
AI summary
A time of flight camera device comprises an light source for illuminating an environment including an object with light of a first wavelength; an image sensor for measuring time the light has taken to travel from the light source to the object and back; optics for gathering reflected light from the object and imaging the environment onto the image sensor; driver electronics for controlling the light source with a high speed signal at a clock frequency; and a controller for calculating the distance between the object and the illumination unit. To minimize power consumption and resulting heat dissipation requirements, the light source/driver electronics are operated at their resonant frequency. Ideally, the driver electronics includes a reactance adjuster for changing a resonant frequency of the illumination unit and driver electronics system.