OLED Global Dimming via Low-Potential Power Supply Voltage Switching
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Solution Overview
Problem
Existing organic light-emitting display devices face limitations in global dimming control due to the restricted duty ratio adjustment range of EM switch elements, leading to inadequate luminance variation and reduced reliability of EM switch elements over time.
Innovation Solution
A display device and method that eliminate the need for EM switch elements by using a power supply to generate a low-potential power supply voltage that switches between light-on and light-off levels, allowing for expanded duty ratio adjustment and luminance control across a wider range during addressing and blank periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If EM switch elements are used for global dimming control during vertical blank period, then luminance control is achieved, but duty ratio adjustment range is limited and reliability deteriorates due to extended driving period
Solution Approach 1:
The patent extracts the global dimming control function from the EM switch element and relocates it to the low-potential power supply voltage. By removing the dimming control responsibility from the EM switch, the switch element is no longer subjected to extended driving periods, thereby resolving the reliability deterioration while maintaining luminance control capability through the power supply voltage modulation.
Solution Approach 2:
The patent introduces the low-potential power supply voltage as an intermediary to achieve global dimming control. Instead of using the EM switch element directly for dimming, the power supply voltage acts as a mediator that modulates the luminance during the addressing period, thereby eliminating the need for extended EM switch driving and improving reliability.
2Illumination intensity
If EM switch elements control duty ratio during vertical blank period, then global dimming is achieved, but duty ratio adjustment range remains limited
Solution Approach 1:
The patent applies dynamics by transitioning from static EM switch control during a fixed vertical blank period to dynamic power supply voltage control during the addressing period. This dynamic approach allows the duty ratio to be adjusted continuously throughout the addressing period, significantly expanding the adjustable range and improving adaptability for various luminance requirements.
Solution Approach 2:
The patent changes the controlling parameter from EM switch duty ratio (constrained by vertical blank period) to low-potential power supply voltage level (adjustable throughout addressing period). This parameter change enables broader duty ratio adjustment range and more flexible luminance control, directly addressing the limited adaptability of the previous approach.
3Ease of operation
If EM switch elements are driven longer than other switch elements, then global dimming control is enabled, but stress increases and deterioration accelerates
Solution Approach 1:
The patent extracts the dimming control function from the EM switch element and assigns it to the power supply circuit. This extraction equalizes the driving period of all switch elements within the addressing period, eliminating the extended driving period that caused increased stress and accelerated deterioration, thereby improving switch element durability while maintaining dimming control capability.
Solution Approach 2:
The patent implements prior cushioning by redistributing the driving workload among all switch elements during the addressing period. By ensuring that no single switch element (including EM switch) is driven longer than others, the design preemptively prevents excessive stress accumulation and deterioration, extending the overall system lifespan.
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 enables linear control of screen luminance and extends the lifespan of driving elements by reducing stress on switch elements, improving the reliability and efficiency of global dimming in organic light-emitting display devices.
Implementation Method 1
a power supply configured to generate a low-potential power supply voltage which is applied to a corresponding light emitting element included in each pixel, the low-potential power supply voltage switching between a first level at which a light emitting element in each respective pixel is capable of emitting light and a second level at which the light emitting element in each respective pixel is not capable of emitting light
Data Source
AI summary
A display device comprises: a display panel including a first display area comprising a first pixels, and a second display area comprising a second pixels, each pixel including a light emitting element; a data driver circuit configured to output data voltages of an image to the first and second pixels; a gate driver configured to output scan signals to the first and second pixels; and a power supply configured to generate a low-potential power supply voltage that is applied to the light emitting element included in each pixel, the low-potential power supply voltage switching between a first level such that the light emitting element is capable of emitting light, and a second level such that the light emitting element cannot emit light, wherein a frame period of the display device includes an addressing period during which the low-potential power supply voltage switches from the second level to the first level.