LED Driving Circuit Voltage Sampling for Stable Illumination

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Solution Overview

Problem

Conventional light illumination modules for LCDs suffer from increased noise and unstable light intensity due to constant variation in driving voltage caused by different on/off states of LED strings, leading to reduced reliability and display quality.

Innovation Solution

The solution involves a driving circuit that samples end voltages only when all LED strings are turned on, maintaining a consistent voltage value until they are turned on again, thereby reducing noise and stabilizing light intensity. This is achieved through an integrated circuit that includes a scaler and a driving circuit, which can be integrated into a single chip, allowing for better control of LED operations and reduced system noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the driving circuit controls the driving voltage according to sampled voltages of the second ends of LED strings, then the LED strings can be controlled to turn on/off individually, but the voltage value of the driving voltage constantly varies, leading to increased noise and unstable light intensity

Engineering Contradiction:

ImproveLED string on/off controlVSAvoidlight intensity stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by ensuring all LED strings are turned on before performing voltage sampling. This preparatory step establishes a consistent initial state where the driving voltage is stable and not affected by partial LED string activation, thereby eliminating noise during the critical measurement phase while still allowing individual LED string control functionality

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If the driving circuit samples voltages at different times when LED strings are in different on/off states, then individual LED string control is achieved, but the driving voltage becomes a noise source due to constant variation

Engineering Contradiction:

Improveindividual LED string controlVSAvoidnoise

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary action by turning on all LED strings before voltage sampling occurs. This ensures that the driving voltage is in a stable state during sampling, preventing it from becoming a noise source. The individual LED string control is maintained by subsequently adjusting which strings remain on or turn off after the sampling phase

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the potential harm of voltage variation into a benefit by using the stable voltage state (when all LED strings are on) specifically for sampling purposes. The voltage variation that would normally occur during operation is actually utilized as a control mechanism - by temporarily maintaining all strings on during sampling, the system gains accurate voltage measurements without compromising the overall individual string control capability

Inventive Principle:

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

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 approach effectively reduces noise in the light illumination module, stabilizes light intensity, and enhances application flexibility by maintaining a consistent driving voltage, improving the reliability and quality of the displayed image.

Implementation Method 1

a sampling operation of end voltages is performed only when all of light emitting diode (LED) strings are turned on

Methodology Applied

Scientific EffectVoltage sampling:

Implementation Method 2

maintaining a consistent voltage value until they are turned on again

Methodology Applied

Scientific EffectVoltage maintenance:

Implementation Method 3

Light emitting diodes (LEDs) are generally used as light sources, for example, used as a backlight module of a liquid crystal display (LCD)

Methodology Applied

Scientific EffectLight emitting diode effect: Light Emitting Diode

Data Source

PatentUS8664868B2Image processing circuit and light illumination module

Publication Date: 2014.03.04 NOVATEK MICROELECTRONICS CORP

AI summary

An image processing circuit and a light illumination module are provided. The light illumination module has an integrated circuit and a plurality of light emitting diode (LED) strings connected in parallel. The integrated circuit could be the image processing circuit. Each of the LED strings has a plurality of LEDs connected in series. The integrated circuit has a driving circuit coupled to the LED strings. The driving circuit supplies a driving voltage to first ends of the LED strings to drive the LED strings. The driving circuit is also configured to maintain a voltage value of the driving voltage obtained while all of the strings of the light emitting diodes are turned on, until all of the LED strings are turned on again. Accordingly, the interference of the LED strings is decreased, and the LED strings operate more stably.