Liquid Crystal Display Driving Method for Power Reduction

Solution Overview

Problem

Liquid crystal display devices face issues with power consumption and image deterioration due to continuous electric field application during idle periods, leading to increased power usage and potential image retention after the device is turned off.

Innovation Solution

A method is introduced where a fixed potential is applied to the capacitor before powering off the device, ensuring the liquid crystals return to an initial state without an electric field, using a semiconductor element with low off-state current to maintain image stability and reduce power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If voltage is continuously applied to liquid crystals during idle periods to maintain image display, then the image display function is maintained, but liquid crystals are deteriorated and power consumption is increased

Engineering Contradiction:

Improveimage display functionVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies a fixed potential to the capacitor before powering off the device, ensuring the liquid crystals are in the initial state (no electric field) when power is turned off. This preliminary action prevents continuous voltage application during idle periods, reducing power consumption while maintaining image quality through the capacitor's charge retention

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the voltage parameter by applying a fixed potential to the capacitor before power-off, transitioning the liquid crystals from a response state to an initial state. This parameter change allows the device to maintain image display function while reducing power consumption during idle periods

Inventive Principle:

Principle #35Parameter changes

2Reliability

If voltage is continuously applied to liquid crystals during idle periods to maintain image display, then the image display function is maintained, but liquid crystals are deteriorated

Engineering Contradiction:

Improveimage display functionVSAvoidliquid crystal deterioration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a fixed potential to the capacitor before powering off the device, ensuring the liquid crystals are in the initial state (no electric field) when power is turned off. This preliminary action prevents continuous voltage application during idle periods, reducing power consumption while maintaining image quality through the capacitor's charge retention

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful effect of continuous voltage application into a beneficial outcome by using the capacitor to store charge and maintain the fixed potential. This allows the liquid crystals to remain in the initial state without continuous power supply, preventing deterioration while maintaining image display function

Inventive Principle:

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

3Duration of action of stationary object

If image data remains on the screen after power source is turned off, then the display state is maintained, but image retention issues occur and power consumption increases

Engineering Contradiction:

Improvedisplay state maintenanceVSAvoidpower consumption

Core Design Contradiction:

Duration of action of stationary objectVSLoss of energy

Solution Approach 1:

The patent applies a fixed potential to the capacitor before powering off the device, ensuring the liquid crystals are in the initial state (no electric field) when power is turned off. This preliminary action prevents continuous voltage application during idle periods, reducing power consumption while maintaining image quality through the capacitor's charge retention

Inventive Principle:

Principle #10Preliminary action

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 effectively reduces power consumption and maintains image quality by preventing unnecessary electric field application, thus enhancing the reliability and longevity of the liquid crystal display device.

Implementation Method 1

A liquid crystal display device has a pixel structure in which a charge is accumulated in a capacitor and voltage applied to the liquid crystals is maintained by the charge

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

When voltage is applied to the liquid crystal element, electric field is generated and applied to the liquid crystals; therefore, the liquid crystals respond, so that an image is displayed

Methodology Applied

Scientific EffectLiquid crystal response to electric field: Liquid Crystals

Data Source

PatentUS9448451B2Driving method of liquid crystal display device

Publication Date: 2016.09.20 SEMICON ENERGY LAB CO LTD

AI summary

It is an object to provide a liquid crystal display device and a driving method of a liquid crystal display device in each of which deterioration of an image display function can be suppressed and power consumption can be sufficiently reduced. In the liquid crystal display device, a fixed potential is input to a capacitor before a power source is turned off, so that a potential difference between electrodes of the capacitor disappears (capacitance becomes almost zero) such that electric field is not applied to liquid crystals, whereby the liquid crystals are in an initial state. When the supply of the power source is stopped after an initial-state image is displayed, unnecessary electric field is not continuously applied to the liquid crystals in an off state, whereby the liquid crystals can be in the stable initial state; therefore, the liquid crystals can be prevented from deteriorating.