Signal-Line Output Buffer Layout for LCD Polarity Inversion

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Solution Overview

Problem

Existing signal-line driving circuits for liquid-crystal display devices face issues with complex circuit configurations, high power consumption, large layout areas, and deteriorating characteristics, particularly in high-definition applications with increasing operating frequencies.

Innovation Solution

A signal-line driving circuit with an output buffer section using positive- and negative-polarity operating amplifiers and switch groups to selectively supply signal voltages to signal lines, eliminating switches on output paths to reduce layout area and improve settling processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a rail-to-rail output analog buffer circuit is used for polarity inverting operations, then the polarity inversion capability is achieved, but the circuit configuration becomes complex, power consumption increases, and layout area increases

Engineering Contradiction:

Improvepolarity inversion capabilityVSAvoidcircuit configuration complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The output buffer section is divided into two independent operational amplifiers: a positive-polarity operational amplifier for generating positive polarity signal voltages and a negative-polarity operational amplifier for generating negative polarity signal voltages. This segmentation allows each amplifier to be optimized for its specific polarity function, simplifying the overall circuit configuration while maintaining polarity inversion capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention combines the positive and negative polarity operational amplifiers within a single output buffer section, allowing both polarity operations to be performed integratedly. This merging approach reduces the need for separate circuits for each polarity, thereby reducing overall circuit complexity and layout area while maintaining full polarity inversion functionality

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If output selectors with switches are used to selectively supply positive and negative signal voltages, then polarity selection is achieved, but the element size increases and settling process worsens

Engineering Contradiction:

Improvepolarity selection capabilityVSAvoidlayout area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The invention extracts and eliminates the switch components from the output buffer section entirely. Instead of using switches to select between positive and negative polarity voltages, the design directly uses the positive-polarity and negative-polarity operational amplifiers to generate and supply the respective polarity voltages to the signal lines, thereby reducing layout area and improving settling characteristics

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Rather than using a single operational amplifier with switches to select polarity (the conventional approach), the invention inverts the approach by using two operational amplifiers that inherently provide different polarities. This inversion of the design paradigm eliminates the need for switches and their associated area and settling issues

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If switches are placed on output paths to select signal lines, then signal line selection is achieved, but circuit complexity and current consumption increase

Engineering Contradiction:

Improvesignal line selection capabilityVSAvoidcurrent consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The invention removes switches from the output paths of the operational amplifiers, eliminating the need for active switching components that consume current. The signal line selection and polarity delivery are achieved directly through the operational amplifiers' output capabilities, reducing current consumption while maintaining operational flexibility

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS9275596B2Signal-line driving circuit, display device and electronic equipments

Publication Date: 2016.03.01 SATURN LICENSING LLC

AI summary

A signal-line driving circuit configured to supply a signal voltage having the positive or negative polarity to each of signal lines connected to display cells arranged to form a matrix as cells each to be subjected to a polarity inversion driving operation according to inversion of the polarity of the signal voltage, the signal-line driving circuit including an output buffer section, wherein the output buffer section employs a positive-polarity operating amplifier, a negative-polarity operating amplifier, a first output buffer, a second output buffer, and a switch group.