Driving Circuit PLC Gamma Voltage Transmission

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Solution Overview

Problem

Current display device driving circuits face challenges with signal quality and panel damage due to signal reflections and heating issues in both chip-on-glass (COG) and chip-on-film (COF) architectures, with COG being cost-effective for small displays but prone to signal degradation and COF being suitable for large displays but requiring a large assembly area and generating noise.

Innovation Solution

A driving circuit utilizing power-line communication (PLC) technology to transmit Gamma voltages, image data, and control signals through reduced wire paths on a printed circuit board (PCB), with source drivers in a COF architecture that include Hi-z components, low pass filters, resistors, and capacitors to prevent voltage drops and noise, and a pre-charging mechanism to reduce thermal noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If COG architecture is used to reduce assembly area, then PCB area is reduced, but signal quality deteriorates due to signal reflections

Engineering Contradiction:

ImprovePCB assembly areaVSAvoidsignal quality

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent introduces a damping resistor as an intermediary element in the signal transmission path between the source driver IC and the display panel. This damping resistor acts as a mediator that absorbs signal reflections and prevents them from causing quality degradation, thereby maintaining reliable signal transmission while using the space-efficient COG architecture.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If COF architecture is used to improve signal quality, then signal reflections are reduced, but PCB assembly area increases due to more wires

Engineering Contradiction:

Improvesignal qualityVSAvoidPCB assembly area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts the damping function from the overall system design and implements it specifically at the critical interface between the source driver IC and the display panel. By placing damping resistors only where signal reflections occur (in the COG architecture's transmission path), the solution achieves signal quality improvement without requiring the extensive wiring of COF architecture.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If COF architecture is used to avoid panel damages, then bonding defects are prevented, but wires and film generate signal noises and heating

Engineering Contradiction:

Improvepanel durabilityVSAvoidsignal noise and heating

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the potentially harmful signal reflections into a manageable phenomenon by using damping resistors to absorb them. Instead of avoiding reflections through complex COF wiring, the solution embraces the COG architecture's simplicity and uses the damping resistors to transform the harmful reflected signals into harmless energy dissipation, thereby reducing noise and heating while maintaining panel durability.

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

This solution improves signal quality, reduces PCB size, and decreases operational temperature and power consumption, addressing the limitations of both COG and COF architectures by enhancing signal transmission and reducing thermal issues.

Implementation Method 1

the first and second Gamma reference voltages are transmitted through the first and second transmission lines, respectively

Methodology Applied

Scientific EffectPower-line communication (PLC):

Implementation Method 2

first and second low pass filters electrically coupled to the first and second Hi-z components, respectively, for removing high frequency components of the input signal

Methodology Applied

Scientific EffectLow pass filter: Filter (electronic)

Implementation Method 3

each capacitor electrically coupled between a respective transmission line and a respective input of the receiver, for removing DC component of the input signal and passing AC component of the input signal

Methodology Applied

Scientific EffectCapacitance coupling: Capacitance

Data Source

PatentUS9478194B2Driving circuit and display device of using same

Publication Date: 2016.10.25 AU OPTRONICS CORP

AI summary

In one aspect of the invention, a driving circuit has a PCB, a transmitter disposed on the PCB for providing an input signal, first and second transmission lines disposed on the PCB and electrically coupled to the transmitter for transmitting the input signal, and a plurality of source drivers formed in a COF architecture disposed between the PCB and the display panel. The input signal is an encoded signal including first and second Gamma reference voltages control signals, and image data. The first and second Gamma reference voltages are transmitted by the PLC technology through the first and second transmission lines, respectively. The driving circuit is implemented with differential transmission of the Gamma voltages, the image data and the control signals.