LED Driver Stabilizing Output Current During Initial Boosting
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Solution Overview
Problem
Conventional LED driver apparatuses experience distortion in constant current due to repeated weakening and strengthening of voltage boosting, leading to instability in output voltage and current during initial driving of LED arrays.
Innovation Solution
The proposed LED driver apparatus includes a comparison voltage generating unit that measures feedback voltage and supplies a difference between the measured feedback voltage and a target voltage as a comparison voltage to a PWM signal generating unit, controlling the DC-DC converter to stop boosting operations when the driving voltage reaches a certain reference voltage, ensuring stable output voltage and current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is immediately performed when high driving voltage is applied to LED arrays, then voltage boosting is weakened to prevent overvoltage, but driving voltage becomes lower than target voltage causing current distortion
Solution Approach 1:
The patent applies preliminary action by detecting whether the LED array is in an initial driving state before performing feedback control. When initially driven, the system prevents feedback control from weakening the boosting voltage, allowing voltage to reach target level without distortion. The controller only enables feedback control after detecting that driving voltage has stabilized, thereby preventing current distortion while maintaining voltage stability.
2Reliability
If driving voltage is repeatedly weakened and strengthened to converge to target voltage, then voltage is adjusted to target level, but constant current becomes distorted due to feedback time delay
Solution Approach 1:
The system performs preliminary detection of the initial driving state before applying feedback control. By identifying when the LED array is first powered on, the controller prevents repeated weakening and strengthening of boosting voltage during the critical initial phase. This eliminates oscillations in constant current that would otherwise occur due to feedback time delays, while still achieving voltage convergence to the target level.
3Productivity
If high driving voltage is applied to turn on all LED arrays, then all arrays are activated and constant current flows, but subsequent feedback control causes voltage to drop below target
Solution Approach 1:
The patent applies preliminary action by detecting the initial driving state before feedback control is engaged. During initial activation with high driving voltage, the system prevents feedback control from reducing the boosting voltage, thereby maintaining stable driving voltage at or above target level. This ensures all LED arrays remain activated with constant current flow without subsequent voltage drops that would cause instability.
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 stabilizes the output voltage and current to the LED arrays by preventing distortion in the driving current, maintaining a consistent amplitude and ensuring efficient operation.
Implementation Method 1
a pulse width modulation (PWM) signal generating unit configured to generate a PWM signal according to a comparison voltage, and a DC-DC converter configured to supply a driving voltage to the LED array using the PWM signal
Data Source
AI summary
A light-emitting diode (LED) driver apparatus is provided. The LED driver apparatus includes a pulse width modulation (PWM) signal generating unit, a DC-DC converter, and a comparison voltage generating unit. The PWM signal generating unit generates a PWM signal according to a comparison voltage. The DC-DC converter supplies a driving voltage of an LED array by using the PWM signal. The comparison voltage generating unit measures a feedback voltage of the LED array and supplies a difference between the measured feedback voltage and a target voltage as a comparison voltage to the PWM signal generating unit. The comparison voltage generating unit supplies a second reference voltage as a comparison voltage to the PWM signal generating unit from a time when the driving voltage is higher than or equal to a first reference voltage to a time when the driving voltage reaches the target voltage.