Subpixel Driving Circuit Reference Node Line Compensation
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Solution Overview
Problem
Electroluminescent display devices face issues with non-uniform vertical luminance and crosstalk due to the lack of consideration for voltage drops in subpixel driving circuits, leading to picture quality problems.
Innovation Solution
A subpixel driving circuit design that includes a compensation transistor to provide a reference voltage to subpixels through a reference node line, excluding high potential voltage, thereby compensating for time-varying characteristics and voltage drops, ensuring uniform luminance and preventing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high potential voltage is applied to subpixels through power lines, then driving current is provided to light emitting diodes, but voltage drop occurs causing non-uniform vertical luminance and crosstalk
Solution Approach 1:
The patent segments the voltage application by introducing a reference node line separate from the power line. The reference voltage is applied to reference nodes through this dedicated line, while the power line carries high potential voltage. This segmentation allows independent control and compensation of voltage drops, resolving the contradiction between providing sufficient driving current and maintaining luminance uniformity.
Solution Approach 2:
The reference node line acts as an intermediary between the power supply and the subpixel driving circuits. By introducing this intermediate reference voltage path, the patent enables compensation for voltage drops occurring in the power line, thus maintaining accurate voltage levels at subpixels without reducing the driving current capability.
2Reliability
If compensation methods are applied to time-varying characteristics, then threshold voltage changes are compensated, but voltage drop in voltage applying line is not considered causing picture quality issues
Solution Approach 1:
The reference node line serves as an intermediary reference voltage path that is not affected by the voltage drop in the power line. By using this intermediate reference, the compensation circuit can accurately measure and compensate for threshold voltage changes without being influenced by the harmful voltage drop effect in the power delivery path.
Solution Approach 2:
The patent creates an equipotential reference path through the reference node line, ensuring that all subpixels have access to a stable reference voltage level. This equipotential reference allows accurate compensation of time-varying characteristics while eliminating the harmful effects of voltage drops that occur in the high potential power lines.
3Ease of operation
If reference voltage is applied to all subpixels through power lines, then driving is enabled, but crosstalk occurs between adjacent subpixels
Solution Approach 1:
The patent segments the voltage reference system by providing dedicated reference nodes to each subpixel through the reference node line. This segmentation isolates the reference voltage paths of adjacent subpixels, preventing crosstalk while maintaining ease of operation. Each subpixel receives its reference voltage independently through this dedicated path.
Solution Approach 2:
The reference node line acts as an intermediary that delivers reference voltage to each subpixel independently. This intermediate path prevents direct electrical coupling between adjacent subpixels that would cause crosstalk, while still enabling easy driving through the maintained reference voltage levels.
Data Source
AI summary
An electroluminescent display device comprises a pixel including a plurality of subpixels; a plurality of power lines for providing a power voltage to the plurality of subpixels; a data line for providing data signals to the plurality of subpixels; a plurality of gate lines for providing gate signals to the plurality of subpixels; and a reference node line for connecting a plurality of reference nodes included in the plurality of subpixels, wherein each of the subpixels comprises a light emitting diode and a subpixel driving circuit for controlling light emission of the light emitting diode, and wherein the subpixel driving circuit provides a driving current without including a high potential voltage to the light emitting diode as a reference voltage that is applied from one of the plurality of power lines to the reference node included in the subpixel driving circuit, and some of the plurality of subpixels include a compensation transistor connected to the reference node receiving the reference voltage.