OLED Driving Circuit Protection Against Initial Over-Current
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Solution Overview
Problem
OLED display devices face damage and operation errors in driving circuits during initial driving due to over-currents when applying current feedback algorithms to prevent luminance variations from external temperature or ambient light.
Innovation Solution
Applying black data to pixels during a predetermined period after system power is applied, detecting driving current during a non-emission period, and adjusting gamma voltage to maintain ideal luminance, thereby preventing damage and errors in the current feedback algorithm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If driving voltages are supplied to OLEDs during initial driving, then pixels emit light for display, but great currents flow through the driving voltage supply line causing over-current damage and operation errors
Solution Approach 1:
The patent applies black data to pixels before supplying driving voltages during initial driving. This preliminary action ensures that when driving voltages are applied, the OLEDs are already in a state that prevents excessive current flow, thereby avoiding over-current damage and operation errors in the driving circuit while still enabling initial display functionality
Solution Approach 2:
The patent uses black data application as a preventive measure before driving voltage supply. The black data creates a preliminary condition that counteracts the potential harmful effect of over-current, protecting the driving circuit from damage and errors during the initial driving phase
2Measurement precision
If current feedback algorithm is applied to prevent luminance variation, then ideal luminance corresponding to pixel data is achieved, but over-currents during initial driving cause damage and operation errors
Solution Approach 1:
The patent applies black data before driving voltage supply during initial driving, creating a preliminary condition that prevents over-current flow. This allows the current feedback algorithm to operate safely without causing damage or errors, while still achieving accurate luminance control when normal pixel data is applied
Solution Approach 2:
The patent converts the potentially harmful over-current condition during initial driving into a beneficial situation by applying black data first. This transforms what would be a damaging scenario into an opportunity to safely initialize the display while maintaining the luminance control benefits of the current feedback algorithm
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
Prevents damage to driving circuits and operation errors during initial driving, ensuring stable luminance compensation against external environmental conditions.
Implementation Method 1
When driving voltages are applied to the anode electrode and the cathode electrode, and holes supplied via the hole injection layer HIL and the hole transport layer HTL and electrons supplied via the electron injection hole EIL and the electron transport layer ETL are moved to the emission layer to form the exciton, and in turn the emission layer EML emits light.
Data Source
AI summary
A driving method of an OLED display device having a plurality of pixels each including an OLED which emits light in response to pixel data, includes applying black data to the pixels during a predetermined period directly after system power is applied, supplying driving voltages to the OLEDs during initial driving where the black data is applied to the pixels, detecting a driving current flowing through the OLEDs by the black data at a first non-emission period after at least one frame has elapsed from a time point where the driving voltages are supplied to the OLEDs, and applying pixel data to the pixels for normal driving subsequent to the initial driving.