LTPS-TFT Display Device RGB Signal Inversion for Power Reduction

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Solution Overview

Problem

Existing display devices with LTPS-TFT liquid crystal panels using RGB time division drive face high power consumption due to inefficient signal distribution and amplification, leading to increased energy usage even in partial display modes.

Innovation Solution

The order of RGB selection signals is changed to BGR, and during partial display, the RGB distribution switches are turned off while the equalizer circuit is on, disconnecting power supplies for amplifiers to reduce power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If RGB time division drive is adopted in LTPS-TFT liquid crystal panel, then the number of connection wires is reduced and cost is reduced, but power consumption becomes greater due to high operation frequency of RGB distribution switches

Engineering Contradiction:

Improvenumber of connection wiresVSAvoidpower consumption

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by inverting the application order of display signal voltage to respective signal lines every horizontal period. This periodic inversion balances the operation frequency of RGB distribution switches, reducing overall power consumption while maintaining the RGB time division drive structure that reduces connection wire complexity

Inventive Principle:

Principle #19Periodic action

2Ease of operation

If RGB distribution switches are operated in horizontal period for signal distribution, then signal distribution function is achieved, but power consumption is high due to frequent switching operations

Engineering Contradiction:

Improvesignal distribution functionVSAvoidpower consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent inverts the conventional approach by reversing the application order of display signal voltage to signal lines every horizontal period. This inversion strategy balances the switching operations of RGB distribution switches, reducing the total number of switching cycles and thereby lowering power consumption while preserving signal distribution functionality

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of manufacture

If amorphous silicon TFT is used for liquid crystal display, then manufacturing cost is low, but electron mobility is slow requiring external LSI for drive circuit

Engineering Contradiction:

Improvemanufacturing costVSAvoidelectron mobility

Core Design Contradiction:

Ease of manufactureVSSpeed

Solution Approach 1:

The patent transitions from amorphous silicon TFT to LTPS-TFT by changing the material parameter. LTPS-TFT provides higher electron mobility, enabling the drive circuit to be integrated directly into the liquid crystal panel rather than requiring external LSI, thus improving speed while maintaining manufacturing feasibility

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8154498B2Display device

Publication Date: 2012.04.10 MAGNOLIA PURPLE CORP

AI summary

In a display device using an RGB time division drive system in which RGB data to be supplied to display pixels of three colors RGB are subjected to time-division multiplexing and input to a liquid crystal panel unit, (1) data are input to the liquid crystal panel unit alternately in the order of RGB and BGR every line signal, and a selection signal SC which is in the on-state at a break of one line period is kept in the on-state until the next line period. In addition, (2) over a partial non-display period in partial display, selection signals SA, SB and SC are always in the off-state and an equalize signal EQG is in the on-state.