OLED Gamma Voltage Generator Inversion for Brightness and Heat
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Solution Overview
Problem
Conventional OLED devices experience deterioration of brightness in the low gray scale domain and increased heat generation due to the inverse matching of gamma voltages with gray scale data signals, leading to reduced lifespan of components and higher power consumption.
Innovation Solution
A gamma voltage generator that applies reversely lowered reference voltages to sequentially arranged gamma tabs, with the zeroth input tab electrically isolated from the resistor string, generating gamma voltages that match high gray scale levels with low voltages and low gray scale levels with high voltages, thereby preventing brightness deterioration and reducing heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If gamma voltages are matched inversely with gray scale data signals (lowest gamma voltage for black brightness, highest gamma voltage for white brightness), then the gamma characteristic follows a normal gamma curve, but brightness deteriorates in the low gray scale domain and heat generation increases
Solution Approach 1:
The patent inverts the conventional gamma voltage assignment by applying the highest gamma voltage to the zeroth gray scale level (black brightness) and the lowest gamma voltage to the highest gray scale level (white brightness). This reversal resolves the brightness deterioration in low gray scale domain while maintaining proper gamma characteristics.
Solution Approach 2:
The patent changes the voltage parameter assignment by electrically isolating the zeroth input tab from the resistor string and applying the power supply voltage VDD directly to it, thereby generating the highest gamma voltage for the zeroth gray scale level. This parameter change enables proper brightness control across all gray scale levels.
2Stability of the object's composition
If conventional gamma voltage assignment is used (lowest gamma voltage for black brightness), then the gamma curve is normal, but heat generation increases and component lifespan reduces
Solution Approach 1:
The patent inverts the voltage assignment strategy to apply highest voltage to lowest gray scale and lowest voltage to highest gray scale, which reduces the voltage stress on components during normal operation and thereby reduces heat generation and extends component lifespan.
Solution Approach 2:
The patent converts the potentially harmful high voltage stress into a beneficial configuration by applying it only when needed (at zeroth gray scale level), while using lower voltages for the majority of display levels, thereby reducing overall heat generation and improving reliability.
3Illumination intensity
If the zeroth and first gamma output tabs are physically separated, then black brightness is realized, but device complexity increases
Solution Approach 1:
The patent extracts the zeroth input tab from the resistor string connection and applies the power supply voltage directly to it, thereby achieving proper black brightness without requiring physical separation of output tabs. This simplifies the overall device structure while maintaining the desired functionality.
Data Source
AI summary
A display device, such as a OLED device, and a method of driving the OLED device. The display device includes a gamma voltage generator that generates sequentially decreasing gamma voltages based on sequentially decreasing reference voltages. A data driver selects a gamma voltage from the gamma voltages for driving a pixel based on digital data indicative of a gray scale level for the pixel. In one embodiment the gamma voltage generator includes a resistor string and an input tab that is electrically isolated from the resistor string.