OLED Delay Structure for Brightness Uniformity
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Solution Overview
Problem
Organic light-emitting diodes (OLEDs) suffer from brightness non-homogeneity due to sheet resistance created by the anode layer, resulting in a gradient of brightness distribution where light intensity drops from the edges towards the center of the emitting surface.
Innovation Solution
A circuit design incorporating a delay line with inductive and capacitive elements that propagates power signal pulses in a way that their superposition exceeds the forward voltage of OLEDs only at specific points, ensuring uniform light emission by controlling the timing and strength of the pulses to activate desired OLEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a large-area OLED with a single anode layer is used, then the device area is increased, but brightness non-homogeneity occurs due to sheet resistance
Solution Approach 1:
The anode is divided into multiple segmented anodes (first anode, second anode, third anode, fourth anode) arranged in a matrix pattern across the OLED surface. Each segmented anode can be independently controlled to compensate for brightness non-homogeneity caused by sheet resistance in large-area devices, thereby maintaining uniform brightness across the entire emitting area.
Solution Approach 2:
Different segments of the anode are assigned different control signals and timing characteristics. By locally adjusting the activation timing and duration of each anode segment, the invention compensates for position-dependent brightness variations, ensuring uniform illumination across the large-area OLED surface.
2Ease of operation
If multiple power signal pulses are propagated through a delay structure, then selective activation of OLEDs is achieved, but the circuit complexity increases
Solution Approach 1:
The invention combines multiple functions into the delay structure: it serves as both a timing control mechanism and a signal distribution network. By integrating the delay functionality directly into the anode control circuitry, the patent achieves selective OLED activation without requiring separate complex control circuits for each pixel.
Solution Approach 2:
The delay structure utilizes periodic power signal pulses with specific timing relationships to selectively activate different OLED segments. By controlling the phase and timing of these periodic signals, the invention achieves precise spatial and temporal control over which OLEDs are activated, simplifying the overall control architecture.
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
The solution achieves improved brightness uniformity across the OLED surface by selectively activating OLEDs, reducing the gradient in light intensity and enhancing the overall display performance.
Implementation Method 1
The delay structure comprises an inductive element and a capacitive element
Implementation Method 2
The delay structure comprises an inductive element and a capacitive element
Implementation Method 3
a light-emitting structure which is designed to emit light when it is powered
Data Source
Figure 1~2a
Figure 2b~2c
Figure 3
AI summary
An organic light-emitting diode (35) is described, which comprises a light-emitting structure designed to emit light when it is powered, and a delay structure designed to delay a propagation of at least two power signal pulses (4a_left, 4b_right, 4a_top, 4b_bottom) having a temporal relationship with one another and such a signal strength that a part of the light-emitting structure is driven in dependence on coincidence of the power signal pulses at said part of the light-emitting structure, and a terminal structure designed to receive the at least two power signal pulses (4a_left, 4b_right, 4a_top, 4b_bottom) and to feed the delay structure at its different positions with the at least two power signal pulses (4a_left, 4b_right, 4a_top, 4b_bottom). A circuit for powering said light-emitting structure, as well as a method of operating said organic light-emitting diode (35) is also described.