OLED Pixel Temperature Estimation via Current Sensing
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Solution Overview
Problem
Existing organic light emitting display devices face challenges in accurately estimating pixel temperatures without separate temperature sensors, which affects luminance and image quality due to temperature-dependent characteristics of organic light emitting diodes and current supply circuits.
Innovation Solution
An organic light emitting display device with a temperature estimating unit that integrates current amplitudes from pixels during a temperature sensing period to generate a sensing voltage, using a lookup table to determine pixel temperatures and compensate for data signals accordingly, without requiring separate temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate temperature sensors are used to accurately estimate pixel temperatures, then temperature measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The pixel circuit performs temperature sensing using its own operational characteristics (current amplitude through the organic light emitting diode) without requiring external temperature sensors. The pixel circuit serves dual purposes: displaying images and sensing temperature, thereby eliminating the need for separate temperature sensing hardware.
Solution Approach 2:
The organic light emitting diode and its driving circuit are designed to serve multiple functions: image display and temperature sensing. By utilizing the same current path and components for both purposes, the system achieves temperature measurement without adding separate dedicated temperature sensing hardware.
2Measurement precision
If temperature sensing is performed continuously during normal driving, then temperature compensation accuracy is improved, but power consumption increases
Solution Approach 1:
The system performs temperature sensing periodically by alternating between a first period (image display) and a second period (temperature sensing). During the temperature sensing period, the organic light emitting diode is turned off and current is measured through a different path, allowing temperature measurement without continuous operation.
Solution Approach 2:
Temperature sensing is performed during dedicated time periods before or between image display periods. By preparing temperature data in advance during sensing periods, the system can compensate for temperature effects during image display without requiring continuous sensing operation.
3Device complexity
If the organic light emitting diode is used for both image display and temperature sensing, then device complexity is reduced, but measurement precision deteriorates due to interference from display operations
Solution Approach 1:
The operational cycle is segmented into distinct time periods: a first period for image display and a second period for temperature sensing. During the temperature sensing period, the organic light emitting diode is turned off to eliminate interference from display operations, allowing accurate temperature measurement through current amplitude detection.
Solution Approach 2:
The system dynamically switches the state of the organic light emitting diode and associated transistors between display mode and sensing mode. By controlling the on/off states of the transistors differently during the two periods, the same hardware components serve distinct functions without interference.
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 accurate temperature sensing and compensation of data signals, improving image quality by addressing temperature-related luminance variations without additional hardware, suitable for high-resolution displays.
Implementation Method 1
The organic light emitting display device displays images using organic light emitting diodes that emit light through recombination of electrons and holes
Implementation Method 2
an integrating circuit configured to generate a sensing voltage by integrating the current supplied from each pixel during the temperature sensing period
Data Source
AI summary
An organic light emitting display device includes pixels, a data driver, a scan driver, a control line driver and a temperature estimating unit. The pixels are respectively disposed at intersection portions of data lines, scan lines, sensing control lines and emission control lines. The data driver supplies data signals to the data lines. The scan driver progressively supplies a scan signal to the scan lines. The control line driver progressively supplies a sensing control signal to the sensing control lines during a temperature sensing period, and progressively supplies an emission control signal to the emission control lines during a normal driving period. The temperature estimating unit estimates temperatures of the pixels according to the amplitudes of currents supplied from the pixels through data lines during the temperature sensing period.