Variable Capacitance Feedback Driver for Electro-Optical Panels
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Solution Overview
Problem
Existing drivers for electrooptic panels face challenges in adjusting the drive voltage range without changing the number of gradations or voltage step, particularly when dealing with different colors of light or liquid crystal materials, as they rely on fixed amplifier circuits that cannot easily adapt to varying voltage requirements.
Innovation Solution
A driver circuit configuration that includes a first driving circuit for supplying data signals based on gradation data and a second driving circuit with a computation amplifier, output capacitor, and variable capacitance feedback capacitors, allowing for dynamic adjustment of the voltage range by varying the capacitance values, thereby maintaining the number of gradations and voltage step while accommodating different light colors and materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed gain amplifier circuit is used, then the circuit structure is simple, but the voltage range cannot be adjusted for different light colors or materials
Solution Approach 1:
The patent applies dynamics by making the feedback capacitor's capacitance value variable rather than fixed. The feedback capacitor can switch between different capacitance values (e.g., C1 and C2) to dynamically adjust the amplifier gain, enabling the voltage range to be adapted for different light colors or liquid crystal materials while maintaining a relatively simple circuit structure.
Solution Approach 2:
The patent changes the parameter of capacitance value in the feedback capacitor to adjust the amplifier gain. By switching between different capacitance values (C1, C2, etc.), the gain parameter is varied, which directly controls the output voltage range. This allows the system to adapt to different application requirements without fundamentally changing the circuit architecture.
2Adaptability or versatility
If the gain is changed by changing power source voltage or gradation range, then the voltage range can be adjusted, but the number of gradations or system configuration must be changed
Solution Approach 1:
The patent changes the capacitance parameter of the feedback capacitor instead of changing the power source voltage or gradation range. This allows independent adjustment of the voltage range while keeping the number of gradations constant. The capacitance switching mechanism enables gain adjustment without affecting the fundamental system configuration or manufacturing specifications.
3Productivity
If capacitance driving is used, then the electrooptic panel can be driven, but voltage drop occurs after the source line switch turns on
Solution Approach 1:
The patent uses feedback by connecting the feedback capacitor between the output terminal and the inverting input terminal of the amplifier. This feedback mechanism monitors the output voltage and adjusts the amplification to compensate for voltage drops that occur after the source line switch turns on. The feedback ensures that the actual output voltage matches the intended data voltage, maintaining voltage accuracy while enabling continuous driving capability.
Data Source
AI summary
A driver includes a first driving circuit and a second driving circuit. The second driving circuit includes a computation amplifier, an output capacitor, a first feedback capacitor, and a second feedback capacitor. One end of the output capacitor is coupled to an output node of the computation amplifier, and the other end is coupled to the signal supply line. One end of the first feedback capacitor is coupled to an inverting input node of the computation amplifier, and the other end is coupled to the signal supply line. One end of the second feedback capacitor is coupled to the inverting input node of the computation amplifier, and the other end is coupled to a predetermined potential node. At least one of the first feedback capacitor and the second feedback capacitor is a capacitor with a variable capacitance value.