LED Driving Circuit Standby Pre-Charging for Fast Light Startup
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Solution Overview
Problem
Existing LED driving circuits face challenges with long delays when switching from standby mode to minimum light emitting level and high standby power consumption, particularly in linear driving circuits.
Innovation Solution
A driving circuit that directly charges an output capacitor from the mains supply in standby mode, maintaining a voltage lower than the LED's turn-on voltage but higher than a preset lowest voltage, allowing quick charging when switching to illumination mode, and using a linear current source with reduced power consumption and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a linear driving circuit is used to drive LED loads, then the structure is simple and cost is low, but the delay from standby mode to minimum light emitting level is long and standby power consumption is high
Solution Approach 1:
The patent applies preliminary action by pre-charging the output capacitor to a voltage level close to the LED turn-on voltage during standby mode through a linear power supply connected to mains supply. This preliminary charging action eliminates the long delay that would otherwise occur when the capacitor needs to charge from a lower voltage level after standby mode is activated, thus resolving the contradiction between simple structure and long delay.
2Loss of energy
If a linear driving circuit with large capacitors is used to achieve higher power factor, then the power factor improves, but the standby power consumption increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the voltage level of the output capacitor during standby mode to be lower than the LED turn-on voltage but sufficient to enable quick startup. This parameter optimization allows the circuit to maintain good power factor while minimizing the energy stored in the capacitor, thereby reducing standby power consumption and resolving the contradiction between power factor and standby power consumption.
3Measurement precision
If a switching mode driving circuit is used, then current control accuracy and overall efficiency are good, but the delay from standby mode to minimum light emitting level is long
Solution Approach 1:
The patent applies preliminary action by maintaining the output capacitor charged to a voltage level close to the LED turn-on voltage during standby mode. When a light emitting request is received, the capacitor is already prepared and can immediately supply current to illuminate the LED, eliminating the long delay characteristic of switching mode circuits. This approach preserves the current control accuracy of switching mode circuits while resolving the delay issue.
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 significantly reduces the delay when switching to the minimum light emitting level and decreases standby power consumption, while maintaining a cost-effective and efficient LED driving circuit.
Implementation Method 1
an output capacitor (C1) connected in parallel with the LED load... control the mains supply to linearly charge the output capacitor (C1) in the standby mode
Implementation Method 2
outputs connected to an LED load... current flows through the LED load and charges the output capacitor (C1)
Data Source
AI summary
Embodiments of the present disclosure provide a driving circuit and a lamp comprising the same. The driving circuit comprises inputs connected to a mains supply; outputs connected to an LED load; an output capacitor connected in parallel with the LED load; an LED driving current source connected to the outputs, and configured to convert the mains supply at the inputs to current at the outputs in an illumination mode, such that the current flows through the LED load and charges the output capacitor; and a control circuit configured to receive a standby signal to enable a standby mode, and to control the mains supply to linearly charge the output capacitor in the standby mode, such that an output voltage at the output can be lower than a turn-on voltage of the LED load and is higher than a preset lowest voltage. With the driving circuit, it is advantageous to reduce the delay from the standby mode to a minimum light emitting level, and meanwhile a lower power loss can be realized by linearly charging the output capacitor through the mains supply.