Light Source Driver Circuit for LED Power Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light source driver circuits for LED loads in optical measuring instruments and value document checking devices face challenges in efficiently managing voltage variations and pulsed current operations, leading to inefficiencies and power dissipation issues, especially when dealing with varying pulse sequences and different forward voltages of LEDs.
Innovation Solution
A light source driver circuit with a switching regulator and a current source, featuring a voltage-controllable member and a regulation unit that adjusts the output voltage based on the voltage drop across the light source load, minimizing energy dissipation and compensating for variations in LED forward voltages and temperature fluctuations, while enabling efficient pulsed operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a switching regulator is used to operate light source loads, then power dissipation is reduced, but voltage variations and current ripple increase
Solution Approach 1:
The patent implements a feedback mechanism where the control terminal of the voltage-controllable member is connected to its own output terminal through a feedback path. This allows the circuit to automatically adjust and compensate for voltage variations, maintaining stable operation while preserving the low power dissipation benefits of the switching regulator topology.
2Reliability
If PWM operation is used for brightness regulation, then LED current remains constant, but the circuit cannot deliver steady-state pulse current values immediately after switching on
Solution Approach 1:
The circuit incorporates a start-up mechanism that prepares the necessary voltage conditions before PWM operation begins. The voltage-controllable member and associated circuitry are pre-configured to immediately deliver the correct pulse current values when switching is initiated, eliminating startup delays while maintaining constant LED current during PWM operation.
3Adaptability or versatility
If different LED configurations are used, then application flexibility increases, but forward voltage variations cause inefficiencies
Solution Approach 1:
The patent employs a voltage-controllable member (such as a MOSFET) whose resistance can be dynamically adjusted by changing the control voltage. This allows the circuit to adapt to different LED forward voltages and configurations, maintaining optimal power efficiency across various LED types and arrangements while preserving application flexibility.
4Productivity
If high processing speeds are implemented, then productivity increases, but power dissipation and voltage fluctuations worsen
Solution Approach 1:
The circuit is designed to operate with periodic pulse sequences that match the high-speed processing requirements. By using the voltage-controllable member to efficiently switch current in synchronized periodic pulses, the system achieves high productivity while minimizing power dissipation through optimized duty cycles and pulse timing.
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 ensures efficient operation of LED loads with minimal power consumption, maintaining consistent performance across different LED configurations and temperature conditions, and supports high-speed processing of value documents by optimizing power delivery and reducing unnecessary power dissipation.
Implementation Method 1
a voltage-controllable member (1) whose control terminal (V1,3) can be connected to a voltage source (N2)
Implementation Method 2
The illumination of the objects to be measured that are to be checked is effected by means of at least one light source, in particular an LED
Data Source
AI summary
A light source driver circuit has a switching regulator including a voltage input, a voltage output, and a regulation input; a current source with a switching element and a voltage-controllable member arranged in series with the light source load. A pulse signal is applied to a control terminal of the switching element to connect, in a first switching state of the switching element, a control terminal of the voltage-controllable member to a voltage source and in a second switching state of the switching element not to connect the control terminal of the voltage-controllable member to the voltage source; and a regulation unit. An optical measuring instrument includes a light source driver circuit, a device checks value documents with the light source driver circuit, and a method is provided for operating a light source load with the light source driver circuit.