Active Level Shift Driver Circuit for Slim LCD Black Matrix
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Solution Overview
Problem
The existing active level shift (ALS) driver circuits in liquid crystal display (LCD) devices require a clock generator and a latch circuit to maintain previous ALS voltages, increasing their size and complexity, especially as the external black matrix is slimmed.
Innovation Solution
The ALS driver circuit is simplified by using a configuration of inverters and a transmission gate that outputs alternating current (AC) and direct current (DC) voltage signals based on the gate signal level, eliminating the need for a latch circuit and clock generator, with the AC voltage swinging relative to the DC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a latch circuit and clock generator are used to maintain previous ALS voltage, then the ALS driver can maintain voltage stability, but the size of the ALS driver circuit increases
Solution Approach 1:
The patent extracts and removes the latch circuit and clock generator from the ALS driver circuit. Instead of using these complex components to maintain voltage, the invention uses a simplified circuit that directly generates AC and DC voltages based on gate signal levels, eliminating the need for voltage maintenance mechanisms
Solution Approach 2:
The patent inverts the conventional approach by not trying to maintain a stable DC voltage and then switching it, but rather directly generating the required AC and DC voltages from the gate signal. The ALS driver outputs AC voltage during gate-ON and DC voltage during gate-OFF, reversing the typical voltage maintenance strategy
2Device complexity
If the ALS driver circuit is simplified to reduce size, then the external black matrix can be slimmed, but the ability to maintain previous ALS voltage is reduced
Solution Approach 1:
The simplified ALS driver circuit serves itself by directly generating the required voltages from the gate signal without needing external latch circuits or clock generators. The circuit inherently produces AC voltage when gate is ON and DC voltage when gate is OFF, making the voltage maintenance capability self-contained within the simplified structure
3Device complexity
If AC voltage is output during gate-ON and DC voltage during gate-OFF, then the circuit configuration is simplified, but additional voltage conversion requirements are introduced
Solution Approach 1:
The patent makes the voltage output dynamic by switching between AC and DC voltage types based on the gate signal state. During gate-ON, AC voltage is output; during gate-OFF, DC voltage is output. This dynamic adaptation simplifies the overall circuit configuration while handling multiple voltage signal requirements through a single unified approach
Data Source
AI summary
An active level shift (ALS) driver circuit, a liquid crystal display device including the ALS driver circuit, and a method of driving the liquid crystal display device. A liquid crystal display device having a slim external black matrix may be provided by fabricating the ALS driver circuit using inverters and a transmission gate.