Micro LED Pixel Circuit for Uniform Luminance via Polarity Inversion

Solution Overview

Problem

The challenge lies in arranging micro light-emitting diodes (LEDs) between electrodes in a display device, particularly in achieving uniform luminance despite non-uniform ratios of LEDs, as they have polarity and are difficult to align, especially when nano- or micro-sized.

Innovation Solution

A display device design where micro LEDs are arranged both in a forward and reverse direction between electrodes, with a pixel circuit that generates a driving current and a light-emitting circuit controlled by a control signal, ensuring consistent light emission across different LED configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If micro LEDs are arranged between electrodes in a display device, then light emission function is achieved, but uniform luminance cannot be ensured due to non-uniform LED arrangement ratios and polarity issues

Engineering Contradiction:

Improveluminance uniformityVSAvoidLED arrangement uniformity

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The pixel is divided into multiple sub-pixels, each containing a different arrangement of first and second light-emitting devices. This segmentation allows each sub-pixel to have optimized LED configurations while maintaining overall uniform luminance across the display.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sub-pixels have different local arrangements of light-emitting devices with varying polarities. By optimizing the local composition of forward and reverse connected LEDs in each sub-pixel, the patent achieves uniform overall luminance despite non-uniform local arrangements.

Inventive Principle:

Principle #3Local quality

2Volume of moving object

If nano- or micro-sized LEDs are used, then device miniaturization is achieved, but it becomes difficult to arrange LEDs on electrodes according to polarity

Engineering Contradiction:

Improvepixel sizeVSAvoidLED arrangement difficulty

Core Design Contradiction:

Volume of moving objectVSEase of manufacture

Solution Approach 1:

The pixel is divided into multiple sub-pixels, each containing a different arrangement of first and second light-emitting devices. This segmentation allows each sub-pixel to have optimized LED configurations while maintaining overall uniform luminance across the display.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses both forward-connected and reverse-connected light-emitting devices in complementary metal oxide semiconductor (CMOS) configuration. By inverting the polarity arrangement of LEDs in different sub-pixels, the system achieves uniform luminance output despite the difficulty of precise polarity-based arrangement at micro-scale.

Inventive Principle:

Principle #13The other way round (Inversion)

3Illumination intensity

If LEDs with polarity are connected between electrodes, then light emission is achieved, but non-uniform ratios of connected LEDs cause luminance non-uniformity

Engineering Contradiction:

Improvelight emissionVSAvoidluminance consistency

Core Design Contradiction:

Illumination intensityVSStability of the object's composition

Solution Approach 1:

Different sub-pixels have different local arrangements of light-emitting devices with varying polarities. By optimizing the local composition of forward and reverse connected LEDs in each sub-pixel, the patent achieves uniform overall luminance despite non-uniform local arrangements.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent combines both forward-connected and reverse-connected light-emitting devices within the same pixel structure. By merging these differently polarized LEDs and controlling their combined output through the light-emitting circuit, uniform luminance is achieved despite non-uniform individual arrangements.

Inventive Principle:

Principle #5Merging (Combining)

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 uniform luminance in pixels regardless of LED ratio, improving the display's uniformity and reducing flicker phenomena by alternating emission periods between forward and reverse connected LEDs.

Implementation Method 1

a light-emitting portion including first light-emitting devices that are connected in a forward direction between a first electrode and a second electrode and second light-emitting devices that are connected in a reverse direction between the first electrode and the second electrode

Methodology Applied

Scientific EffectLight-emitting diode effect: Light Emitting Diode

Data Source

PatentUS10964253B2Pixel including light-emitting devices and display device including the pixel

Publication Date: 2021.03.30 SAMSUNG DISPLAY CO LTD

AI summary

Each of pixels of a display device includes: a light-emitting portion including first light-emitting devices that are connected in a forward direction between a first electrode and a second electrode and second light-emitting devices that are connected in a reverse direction between the first electrode and the second electrode; a pixel circuit configured to receive a data voltage in synchronization with a scan signal, generate a driving current based on the data voltage, and output the driving current to a first node; and a light-emitting circuit configured to be controlled by a control signal, provide the driving current to the first light-emitting devices during a first emission period, and provide the driving current to the second light-emitting devices during a second emission period.