OLED Pixel Current Measurement Using Data Line Sensor
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Solution Overview
Problem
Active matrix OLED displays face luminance variations between pixels due to process variations, leading to non-uniform current driving and difficulty in measuring pixel current at high speeds without additional feedback lines.
Innovation Solution
A display device and driving method that utilize a sensor to measure pixel current by supplying a test signal through the data line, detecting the sensing current using an amplifier and current sensor, and compensating data signals based on the measured current, eliminating the need for an additional feedback line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an additional feedback line is used to measure pixel current, then measurement precision is improved, but device complexity and panel circuit size increase
Solution Approach 1:
The patent merges the data line and feedback line functions by using the existing data line to supply test signals for pixel current measurement. The sensor unit is integrated into the pixel circuit, combining measurement functionality with the display circuit structure, thereby eliminating the need for separate feedback lines while maintaining measurement precision.
Solution Approach 2:
The data line is given multi-functionality: it serves both as a data signal transmission line and as a test signal supply line for pixel current measurement. This universal usage of the data line eliminates the need for dedicated feedback lines, reducing device complexity while preserving measurement capabilities.
2Measurement precision
If a test voltage is applied to measure pixel current, then measurement precision is improved, but measuring time increases due to parasitic components in feedback lines
Solution Approach 1:
The patent extracts and eliminates the parasitic components associated with separate feedback lines by using the existing data line for test signal supply. This removal of unnecessary circuit elements reduces parasitic capacitance and inductance, thereby decreasing measuring time while maintaining measurement precision.
Solution Approach 2:
The patent enables faster current measurement by skipping the delay introduced by parasitic components in separate feedback lines. The direct use of the data line for test signal supply allows rapid voltage application and current detection, achieving high-speed measurement capability.
3Manufacturing precision
If process variation is reduced to improve manufacturing precision, then luminance uniformity is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent implements a feedback mechanism where pixel current is measured using the sensor unit and data line, and compensation is applied to correct for process variations. This feedback-based compensation approach achieves luminance uniformity without requiring extremely tight process control, thereby reducing manufacturing complexity and cost.
Solution Approach 2:
The patent uses parameter changes in the driving voltage based on measured pixel current to compensate for process variations. By adjusting operating parameters rather than strictly controlling manufacturing processes, the system achieves luminance uniformity with reduced manufacturing complexity.
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
Enables fast measurement of pixel current, reduces panel circuit size, and compensates for luminance variations without additional feedback lines, improving display performance.
Implementation Method 1
a sensor configured to supply a test signal to the data line and to detect a sensing current flowing to the data line through the driving transistor according to the test signal
Implementation Method 2
an amplifier configured to generate an output voltage according to a voltage difference input to a plurality of input terminals
Data Source
AI summary
A display device according to an embodiment of the present invention includes: a pixel configured to emit light according to a data signal supplied to a data line, a power source voltage supplier configured to supply a power source voltage to the pixel, a driving transistor configured to drive the pixel to be emitted according to the data signal and the power source voltage, and a sensor configured to supply a test signal to a data line and to detect a sensing current flowing to the data line through the driving transistor according to the test signal.