LCD Driving Circuit Digital Delay Temperature Compensation
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Solution Overview
Problem
Existing LCD driving circuits face challenges in accurately controlling delay time periods of voltages due to variations in environmental temperatures, affecting the performance of gate and data drivers.
Innovation Solution
A driving circuit with a digital delay circuit, including a state machine and transistors, is used to precisely control the delay time periods of voltage signals VGH, VDD, and VGL, independent of environmental temperatures, by incorporating a timing controller and bias resistors to manage the activation states of transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If analog delay circuits are used to delay voltage signals, then the circuit structure is simple, but the delay time periods vary with environmental temperature changes
Solution Approach 1:
The patent replaces the analog delay circuit with a digital delay circuit that uses a counter and clock signal generation. This substitution eliminates the temperature-dependent resistance and capacitance variations inherent in analog circuits, achieving precise and temperature-independent delay time control while maintaining reasonable circuit complexity through standardized digital components
Solution Approach 2:
The patent changes the delay mechanism from analog time-constant based (RC circuits) to digital counting-based timing. By using a counter that increments with each clock cycle, the delay time becomes a discrete, programmable parameter that can be precisely controlled without being affected by environmental temperature variations
2Ease of manufacture
If analog delay circuits with resistors and capacitors are used, then the implementation is straightforward, but the delay time periods cannot be accurately controlled due to parameter variations
Solution Approach 1:
The patent replaces the analog delay circuit with a digital delay circuit that uses a counter and clock signal generation. This substitution eliminates the temperature-dependent resistance and capacitance variations inherent in analog circuits, achieving precise and temperature-independent delay time control while maintaining reasonable circuit complexity through standardized digital components
Solution Approach 2:
The patent incorporates a bootstrapping mechanism that preliminarily charges the bootstrapping capacitor before the main delay operation. This preliminary action ensures that the timing reference is established before the delay period begins, improving the accuracy and consistency of the delay time across different manufacturing batches and operating conditions
Data Source
AI summary
An exemplary driving circuit of a liquid crystal display includes a delay circuit (130), a first transistor (140), a second transistor (160), a first bias resistor (R1), and a second bias resistor (R2). The first transistor includes a source electrode for receiving a first voltage signal, and a drain electrode for providing the first voltage signal to a first external circuit. The second transistor includes an emitter electrode for receiving a second voltage signal, and a collector electrode for providing the second voltage signal to a second external circuit. The delay circuit includes a first control pin (137) connected to the gate electrode of the first transistor, and a second control pin (138) connected to the base electrode of the second transistor. The delay circuit is configured for delaying the first voltage signal for a first predetermined time period and the second voltage signal for a second predetermined time period.