LED Drive Circuit Delay Switch for Dimmer Flicker
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Solution Overview
Problem
LED drive circuits connected to dimmer circuits with TRIACs experience flashing or flickering when the power source is turned on, due to unstable voltage states immediately after power activation.
Innovation Solution
Incorporating a delay circuit with a switch that only allows current to flow through the LED array after a predetermined time has elapsed since power activation, ensuring the rectification circuit and LED array are connected directly only when the switch is on, and utilizing a capacitor and capacitor charge circuit to manage the pulsating current, along with a bleeder current circuit to stabilize the dimmer circuit operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the LED drive circuit is connected to a dimmer circuit including a TRIAC, then the LED array can be controlled to emit light with adjustable brightness, but flashing or flicker occurs when the power source is turned on due to unstable voltage states
Solution Approach 1:
The patent applies preliminary action by introducing a delay circuit that prevents the LED array from operating during the initial unstable period after power-on. The delay circuit keeps the switch off for a predetermined time period, allowing the dimmer circuit to stabilize before enabling LED operation. This resolves the contradiction by preparing the system in advance to avoid the flashing problem while maintaining dimmer compatibility.
2Speed
If current flows through the LED array immediately after power activation, then the LED array can emit light without delay, but flashing occurs due to unstable voltage states in the dimmer circuit
Solution Approach 1:
The patent uses an intermediary approach by introducing a delay circuit as a mediator between the power source and the LED array. This delay circuit, controlled by a switch, acts as an intermediate stage that filters out the harmful flashing effect while allowing the beneficial light emission to occur after stabilization. The intermediary element resolves the contradiction by blocking the harmful voltage states while permitting normal operation.
3Reliability
If a delay circuit is introduced to prevent flashing, then the stability of LED operation is improved, but the response time for LED illumination is increased
Solution Approach 1:
The patent applies parameter changes by adjusting the predetermined time period in the delay circuit to optimize the balance between stability and response time. By carefully selecting the delay duration, the circuit achieves sufficient stabilization to eliminate flashing while minimizing the unnecessary delay in LED illumination. This parameter optimization resolves the contradiction by finding the optimal operating point.
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
Prevents flashing by ensuring no current flows through the LED array until the pulsating current reaches a stable level, maintaining light emission efficiency and preventing unintended dimming, thus stabilizing the LED drive circuit operation even with TRIAC-based dimmer circuits.
Implementation Method 1
rectify an alternating-current voltage that is input via a dimmer circuit
Implementation Method 2
delay circuit having a switch, and the delay circuit turns on the switch when a predetermined time elapses after an alternating-current signal is input
Implementation Method 3
light emitting unit including an LED array including LEDs that are connected in series
Data Source
AI summary
An LED drive circuit includes a rectification circuit configured to rectify an alternating-current voltage that is input via a dimmer circuit, a delay circuit having a switch, and a light emitting unit including an LED array including LEDs connected in series, wherein the delay circuit turns on the switch when a predetermined time elapses after the alternating-current current is input, and the rectification circuit and the LED array are directly connected when the switch is on.