Drive Voltage Generating Circuit for Liquid Crystal Display
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Solution Overview
Problem
Conventional liquid crystal displays using amorphous silicon thin film transistors (a-Si TFT) face challenges in maintaining driving capability at varying temperatures, as the gate signal voltage levels required to turn on/off pixels are insufficient at lower temperatures, necessitating a solution to adjust gate-on and gate-off voltage levels accordingly.
Innovation Solution
A drive voltage generating circuit is introduced, comprising a first and second shifter that adjust voltage levels, and a drive voltage controller that adjusts the shifting amounts based on temperature, ensuring the gate driver outputs appropriate gate signals by continuously varying the second drive voltage in response to temperature changes, thereby maintaining pixel operation and display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a-Si TFT is used to generate gate signals, then manufacturing cost and size are reduced, but driving capability deteriorates at low temperature
Solution Approach 1:
The patent changes the voltage level parameters of gate signals dynamically based on temperature. A temperature sensing unit detects temperature changes, and a voltage level adjusting unit modifies the gate-on voltage and gate-off voltage accordingly. This ensures that the gate signals maintain sufficient voltage levels to drive the a-Si TFT across the operating temperature range, resolving the contradiction between using cost-effective a-Si TFT and maintaining reliable driving capability at low temperatures.
2Device complexity
If fixed voltage levels are used for gate signals, then circuit complexity is reduced, but display quality deteriorates under temperature variations
Solution Approach 1:
The patent introduces dynamic adjustment of gate signal voltage levels based on temperature conditions. The voltage level adjusting unit continuously adapts the gate-on and gate-off voltage levels according to the detected temperature, transforming the static voltage system into a dynamic one. This maintains optimal display quality across temperature variations while adding only minimal circuit complexity through temperature sensing and voltage adjustment mechanisms.
Data Source
AI summary
A drive voltage generating circuit which has a first shifter receiving an input voltage and outputting a first drive voltage obtained by first shifting a voltage level of the input voltage; a second shifter receiving outputting the second drive voltage obtained by second shifting a voltage level of the first drive voltage; and a drive voltage controller adjusting one of a shifting amount of the first shifter and a shifting amount of the second shifter in accordance with a surrounding temperature, wherein the second drive voltage is continuously varied in an analog manner, in accordance with the surrounding temperature.