OLED Pixel Circuit Deterioration Sensing via Preliminary Heating
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Solution Overview
Problem
Conventional organic light emitting display devices struggle to accurately sense and compensate for the deterioration of organic light emitting diodes due to changes in temperature and surrounding environments, leading to inconsistent luminance.
Innovation Solution
A pixel circuit design that includes an organic light emitting diode, an organic light emitting diode driving block, a first switch for applying a sensing bias voltage, and a second switch for applying a deterioration sensing voltage, with the switches controlled to ensure consistent sensing conditions by dividing the deterioration sensing mode into two times: one for reaching a predetermined temperature and another for generating sensing data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a deterioration sensing voltage is applied to sense the current flowing through the organic light emitting diode, then deterioration sensing data can be generated, but the sensing accuracy deteriorates due to temperature changes and surrounding environment variations
Solution Approach 1:
The patent applies a preliminary action by heating the organic light emitting diode to a predetermined temperature before applying the deterioration sensing voltage. This preliminary heating ensures that the diode reaches a stable thermal state, eliminating temperature variations that would otherwise affect sensing accuracy. The heating step is performed in advance of the actual measurement, creating consistent initial conditions for reliable deterioration sensing regardless of ambient temperature changes.
2Measurement precision
If the number of sensing operations is increased to improve deterioration detection accuracy, then more sensing data can be collected, but the temperature of the organic light emitting diode changes causing inconsistent sensing results
Solution Approach 1:
The patent performs preliminary heating to a predetermined temperature before each sensing operation, ensuring that the diode starts from a consistent thermal state. This preliminary action stabilizes the temperature condition, allowing multiple sensing operations to be performed with consistent results regardless of the cumulative heating effect of repeated measurements.
3Device complexity
If conventional deterioration sensing is performed without temperature control, then the sensing process is simple, but the luminance compensation accuracy deteriorates due to environmental variations
Solution Approach 1:
The patent introduces a preliminary heating step that raises the organic light emitting diode to a predetermined temperature before deterioration sensing. This additional step, while increasing process complexity, ensures that temperature variations and environmental factors do not affect the sensing results, thereby significantly improving luminance compensation accuracy.
Solution Approach 2:
The patent changes the temperature parameter of the organic light emitting diode by applying a predetermined voltage to heat it to a specific temperature before sensing. This parameter change (temperature control) ensures that the diode operates at a consistent thermal state during measurement, eliminating environmental variations that would otherwise degrade measurement precision.
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 accurate sensing and compensation of organic light emitting diode deterioration regardless of temperature and environment, ensuring consistent luminance and high-quality image display.
Implementation Method 1
an organic light emitting diode having an anode and a cathode
Data Source
AI summary
A pixel circuit includes an OLED, an OLED driving block, a first switch, and a second switch. The OLED has an anode and a cathode connected to ELVSS. The OLED driving block connected between the anode and ELVDD controls a driving current flowing through the OLED, a first switch is turned on or off responding to a first control-signal and transfers a sensing-bias-voltage to the anode when turned on. The second switch is turned on or off responding to a second control-signal and transfers a deterioration-sensing-voltage to the anode when turned on. In a display mode, the first and second switches are turned off. In a deterioration sensing mode, the first switch is turned on and the second switch is turned off during a first time, and the first switch is turned off and the second switch is turned on during a second time.