Bi-directional Scan Driver for Rotated OLED Displays

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Solution Overview

Problem

Conventional organic electroluminescent (EL) display driving methods struggle with bi-directional scanning operations, particularly when pixel circuits are required to function with two different scan signals, as they fail to operate properly in backward scan modes due to reversed signal application orders.

Innovation Solution

A bi-directional signal transmission shift register and signal applier are implemented, allowing for sequential output of signals in opposite directions based on control signals, enabling pixel circuits to operate with first and second scan lines, and applying scan signals accordingly in both forward and backward scan modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional single-direction scan driver is used, then the display operates normally in forward scan mode, but it cannot display images correctly when rotated 180 degrees

Engineering Contradiction:

Improvedisplay operation in rotated statesVSAvoidscan driver structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The scan driver is designed to dynamically switch between forward and backward scanning modes based on control signals. The shift register can change its signal transmission direction, and the scan signal applier can selectively connect scan lines to appropriate signals, enabling the display to adapt to both normal and 180-degree rotated states without requiring separate driver circuits for each orientation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The scan driver is designed to perform multiple functions: it can drive the display in both forward and backward scan modes using the same hardware components. The bi-directional shift register and configurable scan signal applier allow a single driver circuit to replace what would traditionally require separate drivers for different scanning directions and rotations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If scan signals are applied in a fixed sequence to scan lines, then forward scanning works correctly, but backward scanning produces incorrect image display

Engineering Contradiction:

Improvebi-directional scanning capabilityVSAvoidsignal application control

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The scan signal applier is designed to dynamically reconfigure the connection between scan signals and scan lines based on the scanning mode. In forward scan mode, scan signals are applied in the conventional sequence to corresponding scan lines. In backward scan mode, the applier reverses the sequence, applying scan signals to scan lines in reverse order, ensuring correct image display regardless of scanning direction.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

For backward scanning, the system inverts the conventional signal application approach by applying scan signals in reverse sequence to the scan lines. This inversion of the normal signal flow allows the display to correctly render images when scanned from bottom to top instead of top to bottom.

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If pixel circuits are designed for single scan signal operation, then the circuit design is simple, but the pixel circuits cannot operate properly with two different scan signals

Engineering Contradiction:

Improvepixel circuit operation with multiple scan signalsVSAvoidpixel circuit configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Each pixel circuit is segmented to have two separate scan line inputs (first scan line and second scan line) that can independently receive different scan signals. This segmentation allows the pixel circuit to selectively respond to appropriate scan signals based on the scanning mode, enabling proper operation in both forward and backward scan directions without complicating the core pixel circuit functionality.

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 solution ensures that pixel circuits can operate effectively in both normal and 180°-rotated states, maintaining image display consistency regardless of scan direction, by selectively coupling input lines and applying scan signals to the appropriate scan lines in both forward and backward scan modes.

Implementation Method 1

organic electroluminescent (EL) light emitting display utilizing EL light emission of an organic material

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS7427971B2Light emitting display and driving method thereof

Publication Date: 2008.09.23 SAMSUNG DISPLAY CO LTD

AI summary

A light emitting display which includes pixel circuits, each of the pixel circuits being operated by at least two different scan signals and being capable of performing a bi-directional scanning operation. The light emitting display includes a bi-directional signal transmission shift register, the pixel circuits, and a signal applier. Each of the pixel circuits is provided with two or more scan lines. The scan lines include first and second scan lines. The shift register outputs first signals in a first direction in response to a first control signal, and outputs second signals in a second direction opposite to the first direction in response to a second control signal. The signal applier sequentially applies, to the scan lines of the pixel circuits, first scan signals corresponding to respective ones of the first signals or second scan signals corresponding to respective ones of the second signals.