Bidirectional Switches Reduce Common Voltage Buffer Area in LCDs
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Solution Overview
Problem
High-resolution liquid crystal displays face challenges in achieving a narrow bezel design due to the increased load on common voltage circuits, which requires larger buffer sizes, making it difficult to reduce the layout area and maintain a compact form factor.
Innovation Solution
The implementation of primary bidirectional switch circuits that control electrical connections between common voltage lines based on the timing of polarity inversion, allowing for the sharing of electric charge among these lines, thereby reducing the equivalent capacitance and layout area required for common voltage buffers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution is implemented, then display quality is improved, but the load on common voltage circuits increases requiring larger buffer sizes
Solution Approach 1:
The patent merges adjacent common voltage lines by using bidirectional switches to connect them, allowing charge sharing between lines. This combination reduces the total capacitance that buffers need to drive, thereby reducing buffer size and layout area while maintaining high resolution display quality
Solution Approach 2:
The patent dynamically changes the electrical parameters of common voltage lines by controlling the resistance states of bidirectional switches. During different time periods, switches connect or disconnect common voltage lines to adjacent nodes, changing the effective capacitance load and allowing smaller buffers to suffice for high resolution displays
2Power
If common voltage buffers are enlarged to improve current driving capability, then driving capability is improved, but layout area increases making narrow bezel design difficult
Solution Approach 1:
Adjacent common voltage lines are merged through bidirectional switch connections, creating charge sharing paths. This merging reduces the total capacitance load on each buffer, allowing smaller buffers with reduced layout area to provide sufficient current driving capability for high resolution displays
Solution Approach 2:
The patent introduces dynamic control of bidirectional switches that adjust the electrical connection state of common voltage lines in real-time. During pixel writing phases, switches are controlled to optimize charge distribution, enabling smaller buffers to dynamically adapt their driving capability to match display requirements without increasing layout area
Data Source
AI summary
A liquid crystal display (LCD) has a pixel matrix, a plurality of shift registers, a plurality of common voltage generators, a plurality of common voltage buffers, and a plurality of primary bidirectional switch circuits. The shift registers sequentially output gate signals to scan lines of the pixel matrix. The common voltage generators output initial common voltages according to the gate signals. The common voltage buffers are configured to buffer the initial common voltages to output a plurality of common voltages to a plurality of common voltage lines of the pixel matrix. Each of the primary bidirectional switch circuits is configured to control electrical connection between two of the common voltage lines according to one or more gate signals outputted from at least one of the shift registers.