RMS Matrix Display Gray Shades Voltage Encoding

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Solution Overview

Problem

Existing methods for displaying gray shades in passive matrix liquid crystal displays face limitations due to the linear increase in time intervals required, leading to flicker and poor brightness uniformity, especially when attempting to display a large number of gray shades, and often result in high hardware complexity and power consumption.

Innovation Solution

A method that selects each row of the display matrix with a set of discrete select voltages and applies data voltages of the same or opposite polarity, with each magnitude occurring a predetermined number of times, reducing the number of time intervals and voltages needed to achieve a large number of gray shades while maintaining low hardware complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If frame modulation or pulse width modulation is used to display gray shades, then gray shade capability is achieved, but the number of time intervals in a cycle increases linearly with the number of gray shades

Engineering Contradiction:

Improvenumber of gray shadesVSAvoidnumber of time intervals

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The patent changes the parameter of voltage amplitude to encode gray shade information. Instead of using multiple time intervals to represent different gray shades, the invention uses different voltage levels (amplitude modulation) to directly control the liquid crystal response, achieving 256 gray shades with only 8 time intervals per frame.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs dynamic voltage switching during the frame period, where select and data voltages are applied in a time-multiplexed manner with varying amplitudes. The liquid crystal pixels integrate these dynamic voltage applications over time to achieve the desired gray shade levels, reducing the number of discrete time intervals needed.

Inventive Principle:

Principle #15Dynamics

2Quantity of substance

If a large number of gray shades are displayed using frame modulation, then gray shade resolution improves, but flicker is observed in the display

Engineering Contradiction:

Improvenumber of gray shadesVSAvoidflicker

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent applies periodic voltage waveforms to the liquid crystal pixels throughout each frame period. By continuously applying alternating select and data voltages in a periodic manner, the liquid crystal pixels maintain a stable average voltage level that corresponds to the desired gray shade, preventing flicker even when displaying 256 gray shades.

Inventive Principle:

Principle #19Periodic action

3Quantity of substance

If pulse width modulation is used with a large number of gray shades, then gray shade capability improves, but the smallest time interval becomes comparable to or less than the RC time constant

Engineering Contradiction:

Improvenumber of gray shadesVSAvoidsmallest time interval

Core Design Contradiction:

Quantity of substanceVSDuration of action of moving object

Solution Approach 1:

The patent changes from time-width parameter control to voltage amplitude parameter control. By using different voltage amplitudes during fixed time intervals, the invention avoids the problem of time intervals becoming too short to overcome the RC time constant, while still achieving 256 distinguishable gray shades through amplitude variation.

Inventive Principle:

Principle #35Parameter changes

4Loss of time

If amplitude modulation or pulse height modulation is used to display gray shades, then the number of time intervals is reduced, but the number of voltages in data waveforms increases

Engineering Contradiction:

Improvenumber of time intervalsVSAvoidnumber of voltages

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent segments the voltage control into two independent parts: select voltages applied to row lines and data voltages applied to column lines. This segmentation allows each driver to handle fewer voltage levels independently, reducing the overall system complexity while maintaining the ability to display 256 gray shades through the combination of select and data voltage interactions.

Inventive Principle:

Principle #1Segmentation

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 allows for a significant increase in the number of gray shades displayed without flicker, while ensuring good brightness uniformity and reducing hardware complexity and power consumption, by using fewer time intervals and voltages compared to existing techniques like successive approximation and wavelets-based methods.

Implementation Method 1

Method to display gray shades in RMS responding matrix display

Methodology Applied

Scientific EffectRMS voltage response:

Implementation Method 2

passive matrix liquid crystal displays such as twisted nematic (TN) and super twisted nematic (STN) displays

Methodology Applied

Scientific EffectLiquid crystal effect: Liquid Crystals

Data Source

PatentUS8081179B2Method to display gray shades in RMS responding matrix display

Publication Date: 2011.12.20 RAMAN RES INST

AI summary

A method to display gray shades in RMS responding display matrix, includes: selecting each row of the display matrix with a set of “s” discrete select voltages in a sequence or random and applying a set of discrete data voltages to a column of the display matrix wherein the data voltages are of both polarities and energy of the select and data waveforms that are applied to rows and columns are constants during the “s” time intervals for all the rows and columns to display gray shades in RMS responding display matrix.