Switched-Capacitor LED Driver for Ultrashort High-Current Pulses
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Solution Overview
Problem
Current driving circuits for light-emitting diodes, particularly laser diodes, are unable to generate ultrashort light pulses with high amplitude, limiting the precision and range of time-of-flight measurements and posing safety concerns due to power constraints.
Innovation Solution
A driving circuit with an integrated switched capacitor topology and controllable switching circuits that generates signal pulses by charging a capacitor to a reference potential and discharging it to the light-emitting diode, enabling the production of ultrashort sub-nanosecond pulses with high peak output current and amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pulse width of the laser diode is reduced to improve measurement precision and reduce power consumption, then the measurement accuracy and power efficiency are improved, but the amplitude of the light pulse decreases
Solution Approach 1:
The patent employs periodic switching action through controllable switching circuits that rapidly charge and discharge a capacitor to generate periodic ultrashort light pulses. This periodic switching enables precise time measurement through short pulse widths while maintaining high amplitude through rapid charge transfer to the light-emitting diode.
Solution Approach 2:
The patent changes the electrical parameters by charging the capacitor to a reference potential and then rapidly discharging it through the light-emitting diode. This parameter change from charging state to discharge state enables the generation of ultrashort high-amplitude current pulses that simultaneously achieve short duration and high intensity.
2Length of moving object
If the amplitude of the laser pulse is increased to extend measurement range, then the maximum measurable distance is improved, but the power consumption increases
Solution Approach 1:
The periodic switching mechanism charges the capacitor during idle periods and discharges it only during the required pulse duration. This periodic action concentrates energy delivery into ultrashort intervals, achieving high peak amplitude for extended measurement range while keeping average power consumption low through the duty cycle of the switching circuits.
Solution Approach 2:
The capacitor is charged in advance to a reference potential before the light pulse is generated. This preliminary charging action stores energy in advance, allowing the subsequent light pulse to achieve high amplitude without requiring continuous high power input during the measurement process, thus extending range while controlling power consumption.
3Measurement precision
If multiple pulses are sent to achieve required measurement accuracy, then the measurement precision is improved, but the total measurement time and power consumption increase
Solution Approach 1:
The switching circuits are designed to generate periodic ultrashort pulses with precise timing control. By using periodic action with optimized pulse repetition rates, the system can achieve required measurement precision through statistical averaging of multiple pulses while minimizing total measurement time through efficient pulse scheduling and rapid switching.
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 solution allows for more accurate and efficient time-of-flight measurements with reduced power consumption and extended measurement range while ensuring eye safety by enabling higher amplitude pulses without danger.
Implementation Method 1
a capacitor (300) to provide a charge to generate the signal pulse SP
Data Source
AI summary
A driving circuit (10) to generate a signal pulse for operating a light-emitting diode (20) comprises an external terminal (LEDK, LEDA) to connect the light-emitting diode (20) to the driving circuit (10). In a first operating state/pre-charge state of the driving circuit (10), a first controllable switching circuit (100) connects a first side (301) of a capacitor (300) to a reference potential (Vref) and a second controllable switch (200) connects a second side (302) of the capacitor (300) to one of a supply and ground potential (VDD, VSS). In a second operating state of the driving circuit (10), the first controllable switching circuit (100) connects the first side (301) of the capacitor (300) to said one of the supply and ground potential (VDD, VSS) and the second controllable switch (200) connects the second side (302) of the capacitor (300) to the external terminal (LEDK, LEDA) to provide a signal pulse for operating the light emitting diode.