LED Driving Module with Threshold Control for High CRI

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Solution Overview

Problem

Conventional white light emitting diodes (LEDs) have a low color rendering index (CRI), which is addressed by implementing a high CRI using a light emitting device driving module that simultaneously controls a white light emitting device and a red light emitting device, while minimizing power loss by reducing the voltage gap between their on and off states.

Innovation Solution

The module includes a red light emitter and a high voltage white light emitter connected in series, with a controller that independently controls the on/off states based on a threshold voltage, using bipolar junction transistors to manage the power flow and reduce power loss, allowing for a high CRI without degrading luminous efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional LED package uses phosphor to implement high CRI, then the color rendering index is improved, but the luminous efficiency degrades by 20% on average

Engineering Contradiction:
Improvecolor rendering indexVSAvoidluminous efficiency
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent combines a red LED chip and a blue LED chip into a single LED package, where the red LED provides the necessary red spectrum for high CRI and the blue LED excites yellow phosphor to produce white light. This merging approach achieves high CRI without the significant luminous efficiency loss associated with phosphor-only solutions, as each chip contributes directly to the final light output.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a composite structure within the LED package, combining different light-emitting materials (red LED chip and blue LED chip with yellow phosphor) to create a unified light source that achieves both high CRI and maintained luminous efficiency. The composite approach allows optimization of each component's contribution to the overall performance.

Inventive Principle:
Principle #40Composite materials

2Measurement precision

If high CRI is implemented by using a normal white LED and red LED, then the color rendering index is improved, but a separate power supply and control circuits are required

Engineering Contradiction:
Improvecolor rendering indexVSAvoidpower supply and control circuits
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the functions of multiple LEDs and their control systems into a single integrated LED package. By combining the red LED chip and blue LED chip with shared electrical connections and control architecture, the invention eliminates the need for separate power supplies and control circuits that would be required if normal white LED and red LED were used independently, thereby reducing device complexity while maintaining high CRI.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If individual LEDs are selectively turned on and off, then the color rendering index is improved, but power loss increases due to voltage gap between on and off states

Engineering Contradiction:
Improvecolor rendering indexVSAvoidpower loss
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The patent combines multiple LED chips with similar forward voltage characteristics in a way that allows them to be turned on and off simultaneously as a unified group. This merging approach minimizes the voltage gap between on and off states, reducing power loss during transitions while still enabling selective control to achieve high CRI through optimized light output combinations.

Inventive Principle:
Principle #5Merging (Combining)

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 configuration achieves a high color rendering index while minimizing power loss and avoiding the need for separate power supplies and control circuits, simplifying the circuit design and reducing chip area, thus enhancing the efficiency and performance of the light emitting device driving module.

Implementation Method 1

a controller which comprises a switching unit which is connected between the second light emitter and a ground (GND), is turned on by the rectified voltage, and electrically connects an anode of the second LED with the ground

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

a first light emitter which receives the rectified voltage and comprises at least one first LED; a second light emitter which is directly connected to the first light emitter and comprises at least one second LED

Methodology Applied
Scientific EffectLight emitting diode effect: Light Emitting Diode

Implementation Method 3

a light emitting device driving module capable of implementing a high color rendering index

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP2911479B1Light emitting device driving module
Publication Date: 2019.04.03 LG INNOTEK CO LTD
  • EP2911479B1 patent drawingFigure 1~2
  • EP2911479B1 patent drawingFigure 3a
  • EP2911479B1 patent drawingFigure 3b

AI summary

A light emitting device driving module may be provided that includes: a light emitter including a first light emitter and a second light emitter connected to the first light emitter; a rectifier which receives an AC power and outputs a rectified voltage; and a controller which receives the rectified voltage from the rectifier and controls on/offs of the first light emitter and the second light emitter in accordance with a magnitude of the rectified voltage. The light emitting device driving module according to the embodiment controls the on/offs of two or more kinds of the light emitting devices by using the AC power, and thus, drives the light emitting device in such a manner as to have a high color rendering index.