LED Lighting Control Circuit Two-Stage Gate Voltage
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Solution Overview
Problem
Existing lighting control techniques for semiconductor light emitting devices, such as LEDs, face challenges in reducing the time to start lighting while preventing current overshoot, which can lead to emission delays and excessive current generation.
Innovation Solution
A lighting control method and device that control the gate voltage of a switching element connected to the LED in two steps: a rapid initial increase to a first value and a gradual increase to a second value, using a control circuit with capacitors and resistors to manage the voltage and current flow, thereby reducing the time to start lighting and suppressing overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the gate voltage of the FET is increased at a faster rate to shorten the lighting start time, then the time required to start lighting is reduced, but an overshoot phenomenon occurs where an excessively large LED current is temporarily generated
Solution Approach 1:
The gate voltage increase is divided into two distinct phases: a rapid increase from initial value to first value (short time) followed by a gradual increase from first value to second value (long time). This segmentation allows the system to achieve fast lighting start while preventing current overshoot through controlled voltage progression.
Solution Approach 2:
The control circuit dynamically adjusts the rate of gate voltage increase based on the current state. Initially, the voltage increases rapidly to establish conduction quickly, then the rate is reduced to prevent overshoot. This dynamic control strategy optimizes both lighting speed and current stability.
2Object-generated harmful factors
If the increase of the gate voltage of the FET is moderated to prevent overshoot, then the harmful overshoot phenomenon is suppressed, but the time required to start lighting becomes longer
Solution Approach 1:
The voltage increase is segmented into two stages with different rates. The first stage uses rapid increase to minimize time loss, while the second stage uses moderate increase to prevent overshoot. This segmentation resolves the contradiction by allocating different control strategies to different phases of voltage increase.
Solution Approach 2:
The control circuit first rapidly increases the gate voltage to a first value to establish initial conduction and reduce lighting start time. Only after this preliminary action does the circuit gradually increase the voltage to the second value, preventing overshoot while having already achieved fast lighting initiation.
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 approach significantly reduces the time to achieve desired current levels in LEDs while minimizing overshoot, ensuring faster and more controlled lighting activation.
Implementation Method 1
a voltage adding circuit including a capacitor... the control circuit increases a control voltage of the control terminal of the switching element from an initial value to a first value in a relatively short time
Implementation Method 2
a semiconductor light emitting element such as an LED (Light Emitting Diode)... the current flowing through the LED can be detected
Data Source
AI summary
To reduce the time until the start of the lighting while suppressing the overshoot of the current. A method to carry out lighting control of a semiconductor light emitting element using a lighting control device where the lighting control device includes a switching element serially connected to the semiconductor light emitting element and having a control terminal to control a conductive state, and a control circuit to control the control terminal. The method including: increasing a control voltage of the control terminal of the switching element from an initial value to a first value in a relatively short time by the control circuit; and increasing the control voltage of the control terminal of the switching element from the first value to a second value in a relatively long time by the control circuit.