Display Gray-Scale Circuit Prevents Vertical Stripes
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Solution Overview
Problem
Liquid crystal displays experience issues with residual voltages causing vertical gray stripes or bands when initially powered on, due to leakage currents from thin film transistors, before the display controller is initialized, leading to unintended gray-scale levels.
Innovation Solution
A circuit with a voltage divider and switch configuration that generates different sets of gray-scale voltages based on reference voltages, allowing for a common gray-scale level to be displayed initially, such as black, independent of pixel data, by controlling the flow of electric current through the voltage divider.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the display is initially powered on with data drivers driving pixel circuits using residual voltages, then the display shows vertical gray stripes or bands, but the display controller cannot be initialized properly
Solution Approach 1:
The patent applies preliminary action by controlling data drivers to output a common gray-scale voltage (e.g., black level) before the display controller is initialized. This preliminary state prevents harmful gray stripes from appearing during the initialization period, and the common gray-scale voltage is maintained until pixel data is actually received, at which point the data drivers transition to normal operation with distinct gray-scale voltages based on pixel data
2Productivity
If data drivers output distinct gray-scale voltages immediately upon power-on, then pixel data can be displayed, but leakage currents cause unintended gray-scale levels and vertical gray stripes
Solution Approach 1:
The patent applies preliminary anti-action by having data drivers output a common gray-scale voltage (such as black level) during the initialization period before pixel data is received. This preliminary state counteracts the harmful effect of leakage currents that would otherwise cause unintended gray-scale levels and vertical gray stripes. The common gray-scale voltage ensures uniform display output during the critical initialization window, and only after the display controller is properly initialized does the system transition to outputting distinct gray-scale voltages based on actual pixel data
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 solution prevents the display of unintended gray stripes or bands and ensures a uniform black image or common gray-scale level when the display is powered on, reducing blurring in motion images and initializing the display correctly.
Implementation Method 1
the voltage divider dividing a voltage difference between a first input voltage and a second input voltage to generate the set of reference voltages
Data Source
AI summary
A display that includes a circuit to receive pixel data and to generate a first set of gray-scale voltages based on the first set of reference voltages to drive pixel circuits to display respectively different gray-scale levels during a first time period in accordance with the pixel data, and generate a second set of gray-scale voltages based on a second, different set of reference voltages to drive the pixel circuits to display a common gray-scale level during a second time period. For example, the common gray-scale level can be a black level.