LCD Gradation Voltage Circuit for Fast Charging and Output Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Recent liquid crystal display devices require faster writing speeds due to increased frame frequency and outputs, but high wiring resistance on substrates affects string resistance values, leading to delays in output waveforms when trying to maintain high resistance for reduced wiring resistance influence.
Innovation Solution
A liquid crystal drive device is designed with a first gradation voltage generating circuit and a second gradation voltage generating circuit with higher resistance, connected to voltage-follower op amplifiers and DA converters, allowing for high-speed charging of input capacitance while maintaining high string resistor values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the string resistor value is increased to reduce the influence of wiring resistance, then the accuracy of voltage output is improved, but the charging speed of the input capacitance of the op amplifier decreases
Solution Approach 1:
The single string resistor is divided into two separate string resistors (first string resistor and second string resistor) with different resistance values. The first string resistor (lower resistance) is used for rapid charging of the input capacitance, while the second string resistor (higher resistance) provides accurate voltage output. This segmentation allows both functions to be performed simultaneously without compromise.
Solution Approach 2:
Different parts of the voltage generating circuit are assigned different resistance characteristics based on their specific functions. The first string resistor has lower resistance optimized for charging speed, while the second string resistor has higher resistance optimized for voltage accuracy. Each part has localized quality tailored to its functional requirement.
2Speed
If the string resistor value is decreased to increase the charging speed, then the charging speed of the input capacitance is improved, but the influence of wiring resistance increases
Solution Approach 1:
The voltage generating circuit is segmented into two parallel paths: one through the first string resistor for fast charging and another through the second string resistor for accurate voltage reference. This segmentation allows the system to achieve both fast charging and high accuracy simultaneously.
Solution Approach 2:
The second string resistor with higher resistance acts as an intermediary that provides a stable voltage reference less affected by wiring resistance. It mediates between the need for fast charging and the need for accurate voltage output, ensuring that the voltage reference remains stable while charging occurs rapidly.
Data Source
AI summary
The present invention provides a liquid crystal drive device comprising a first gradation voltage generating circuit having a plurality of first wirings led out from a first string resistor thereof, a second gradation voltage generating circuit having a plurality of second wirings led out from a second string resistor thereof having a resistance value higher than the first string resistor and respectively connected to voltage-follower connected op amplifiers, a plurality of DA converters to which the first wirings and the op amplifiers are respectively connected, and an output op amplifier connected to the DA converters respectively.