OLED Display Timing Control for Luminance Inversion
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Solution Overview
Problem
Organic light emitting diode (OLED) display devices experience abnormal phenomena such as luminance inversion, gamma breakdown, and black rising due to duty ratio differences, which deteriorate the display quality of low gray level images.
Innovation Solution
The display device includes a timing controlling unit, data and gate driving units, and a display panel, where the timing of the gate signal is adjusted to eliminate the influence of duty ratio differences, keeping the voltage of the anode constant and maintaining an interval between the emission signal and the gate signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pulse width modulation (PWM) is used to control luminance with the same voltage, then power consumption is reduced and luminance control is achieved, but voltage of the anode changes due to coupling in emission of low gray level, causing luminance inversion, gamma breakdown and black rising
Solution Approach 1:
The patent applies preliminary action by adjusting the timing of the gate signal to turn on before the emission signal in a predetermined time period. This advance timing adjustment prevents voltage changes at the anode during emission, thereby eliminating luminance inversion, gamma breakdown and black rising while maintaining PWM-based power consumption control.
2Reliability
If the timing of gate signal is adjusted to eliminate duty ratio difference influence, then voltage of anode is kept constant and abnormal phenomena are eliminated, but device complexity increases due to multiple gate signals and timing control
Solution Approach 1:
The patent applies dynamics by making the gate signal timing adjustable based on duty ratio. The gate driving unit dynamically adjusts the turn-on timing of gate signals (gate1, gate2, gate3, gate4) according to the specific duty ratio being used, allowing the system to adapt to different operating conditions and eliminate abnormal phenomena while maintaining manageable complexity through systematic timing control.
3Manufacturing precision
If multiple gate signals (gate1, gate2, gate3, gate4) and emission signal are used with adjusted timing, then abnormal phenomena are eliminated and display quality is improved, but device complexity and control difficulty increase
Solution Approach 1:
The patent applies segmentation by dividing the gate control into multiple separate gate signals (gate1, gate2, gate3, gate4) with distinct timing relationships. Each gate signal controls specific transistor operations, and by segmenting the control functions and assigning specific timing to each signal, the patent achieves precise control over the pixel circuit operations to eliminate abnormal phenomena while maintaining systematic manageability.
Data Source
AI summary
A display device includes a timing controlling unit configured to generate an image data, a data control signal and a gate control signal; a data driving unit configured to generate a data signal using the image data and the data control signal; a gate driving unit configured to generate a gate1 signal, an odd gate2 signal, an even gate2 signal, a gate3 signal, a gate4 signal and an emission signal using the gate control signal; and a display panel displaying an image using the gate1 signal, the odd gate2 signal, the even gate2 signal, the gate3 signal, the gate4 signal and the emission signal. A rising timing of the emission signal and a falling timing of the gate3 signal are changed according to a duty ratio.