Capacitive Divider DC Driver for Low Power Lighting Efficiency

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Solution Overview

Problem

Existing driver circuits for low power DC lighting devices, such as LEDs and OLEDs, face inefficiencies in converting AC power to DC power, particularly at low power levels, due to multiple power conversion stages and difficulties in improving efficiency through capacitor charging and controlled half-wave rectification.

Innovation Solution

A high efficiency low power DC driver apparatus utilizing a capacitive divider circuit, a rectifier, and a linear regulator to provide a DC output for low power lighting devices, with optional dimming and soft starting capabilities, avoiding excessive EMI/RFI emissions by using a non-switching regulator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If multiple power conversion stages are used to convert AC power to DC power, then the power conversion can be achieved, but the power efficiency deteriorates

Engineering Contradiction:

Improvepower efficiencyVSAvoidnumber of power conversion stages

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates intermediate power conversion stages from the traditional AC-DC conversion path. By using a capacitive divider circuit directly coupled with a rectifier, the design removes unnecessary conversion stages that were present in conventional multi-stage power supplies, thereby improving power efficiency while maintaining functional capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the power conversion function into distinct functional blocks: a capacitive divider circuit for voltage reduction and a rectifier for AC-DC conversion. This segmentation allows each component to perform its specific function efficiently without the losses associated with multiple interconnected conversion stages, resolving the contradiction between simplicity and functionality.

Inventive Principle:

Principle #1Segmentation

2Use of energy by moving object

If capacitor charging and controlled half wave rectification are used to improve efficiency, then power efficiency can be improved, but the control difficulty increases

Engineering Contradiction:

Improvepower efficiencyVSAvoidcontrol difficulty

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The capacitive divider circuit automatically performs voltage reduction and the rectifier automatically performs AC-DC conversion without requiring complex control circuits. The circuit components self-regulate their operation based on the input AC voltage, eliminating the need for microcontrollers, feedback loops, or complex timing circuits that would increase control difficulty.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The capacitive divider circuit acts as an intermediary between the AC power source and the rectifier, providing passive voltage reduction before rectification. This intermediary component simplifies the overall control architecture by handling voltage management passively, avoiding the need for active control mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If switching regulators are used for power regulation, then the power efficiency can be improved, but the EMI and RFI emissions increase

Engineering Contradiction:

Improvepower efficiencyVSAvoidEMI and RFI emissions

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent converts the potential harm of EMI and RFI emissions into a benefit by deliberately choosing a linear regulator over a switching regulator. While linear regulators are less efficient in general, they eliminate the high-frequency switching noise that causes EMI and RFI problems, making them ideal for low-power applications where electromagnetic cleanliness is critical.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the operational parameters of the power regulation by using a linear regulator instead of a switching regulator. This parameter change trades some efficiency for the elimination of high-frequency switching operations, thereby reducing EMI and RFI emissions to acceptable levels for low-power lighting applications.

Inventive Principle:

Principle #35Parameter changes

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

The solution achieves high efficiency (88-92%) with reduced component count and cost, while minimizing power loss and emissions, effectively powering low power DC lighting devices with improved power conversion and operational longevity.

Implementation Method 1

a capacitive divider circuit with first and second capacitances coupled in series between the input terminals to provide a reduced or divided AC output at an intermediate node

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

A rectifier receives and rectifies the divided AC output to provide a DC output

Methodology Applied

Scientific EffectRectification: Diode

Data Source

PatentUS7960922B2High efficiency low power capacitor charged DC driver

Publication Date: 2011.06.14 SAVANT TECHNOLOGIES LLC

AI summary

A high efficiency low power DC driver apparatus is presented for powering a light source, with a capacitive divider circuit receiving an AC input and providing a divided AC output, a rectifier provide a DC output below ten watts, output terminals coupleable to one or more light sources, and a linear regulator coupled in series with the light source to regulate a drive current flowing through the series circuit.